Release Scan Tools v0.1.0

.gitignore

@@ -0,0 +1,10 @@
+node_modules/
+dist/
+release/*.zip
+release/*.zip.sha256
+coverage/
+playwright-report/
+test-results/
+public/ocr/
+*.tsbuildinfo
+.DS_Store

.npmrc

@@ -0,0 +1 @@
+@add-ideas:registry=https://git.add-ideas.de/api/packages/lotobo/npm/

CHANGELOG.md

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+# Changelog
+
+## 0.1.0 - 2026-09-01
+
+- Add bounded multi-image and camera-picker ingestion with real decoded-pixel checks
+- Add draggable four-corner projective correction and keyboard-accessible handles
+- Add rotation, manual and estimated deskew, brightness, contrast, grayscale,
+  Otsu threshold and manual threshold processing
+- Add retained debounced previews and bounded high-resolution PNG/JPEG exports
+- Add drag-to-reorder page assembly and A4, Letter, or source-sized PDF output
+- Add opt-in local English OCR using bundled same-origin Tesseract.js runtime and model
+- Add editable OCR text export, explicit confidence and memory/accuracy disclosures
+- Add Toolbox shell integration, nested-path offline PWA support, documentation,
+  deterministic packaging, and Chromium/Firefox coverage

CONTRIBUTING.md

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+# Contributing
+
+Run `npm ci`, `npm run check`, and `npm run test:browser` before proposing a change. Keep processing local, preserve explicit byte/pixel/page limits, test transforms with generated non-sensitive images, and never add a silent remote OCR fallback.

LICENSE

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+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

LICENSES/README.md

@@ -0,0 +1,3 @@
+# Licences
+
+The application is GPL-3.0-or-later. Generated release artifacts include an exact runtime dependency licence inventory in `npm-runtime-licenses.txt`.

README.md

@@ -0,0 +1,62 @@
+# Scan Tools
+
+Correct photographed document pages, assemble them, optionally recognize
+English text, and export images or PDFs without sending content away. Scan
+Tools is a local-first module in the add·ideas Toolbox.
+
+## v0.1.0 capabilities
+
+- Add up to 24 browser-decodable PNG, JPEG or WebP images through a file or
+  camera-enabled picker
+- Drag four document corners to apply an actual projective correction; handles
+  also support keyboard movement
+- Rotate in quarter turns, adjust deskew manually, or estimate a text-line
+  correction within ±5 degrees
+- Tune brightness and contrast, retain colour, convert to grayscale, or create
+  black-and-white pages using Otsu or a manual threshold
+- Preserve the previous preview until its debounced replacement is ready
+- Reorder pages with drag and drop, remove them without touching source files,
+  and export the selected page as PNG or JPEG
+- Assemble every corrected page into A4, US Letter, or source-sized image-only
+  PDFs with a configurable margin
+- Run optional English OCR using a bundled integer model and same-origin
+  Tesseract.js WebAssembly runtime; edit and download recognized text
+- Work at nested paths, install as an offline PWA, use the shared system/light/
+  dark themes, and perform no remote content request
+
+## Honest scope and limits
+
+This first release does not automatically detect page corners, remove fingers
+or shadows, process input PDFs, recognize handwriting reliably, or create a
+searchable invisible PDF text layer. OCR confidence is engine evidence, not an
+accuracy guarantee. Perspective correction is high-quality bilinear resampling;
+each new render is lossy unless exported as PNG.
+
+There are explicit limits of 24 pages, 32 MiB and 80 decoded megapixels per
+source image, 24 megapixels for a working source raster, 1.2 megapixels for an
+interactive preview, 10 megapixels per exported page, and 4 megapixels for OCR.
+Optional OCR loads only after confirmation and may use roughly 100–300 MiB of
+transient memory. The bundled model is English only.
+
+Files, decoded pixels, correction settings and OCR text live in memory. The
+same-origin OCR files are included in the release rather than downloaded from a
+CDN. Nothing is uploaded, but an exported image or PDF naturally contains the
+visible page and an exported text file contains the recognized text.
+
+## Development
+
+```sh
+npm ci
+npm run check
+npm run test:browser
+```
+
+`npm run release:artifact` produces a deterministic ZIP and SHA-256 sidecar.
+The build copies pinned OCR assets from installed npm packages into the static
+release; generated `public/ocr/` content is not source-controlled.
+
+## License
+
+GPL-3.0-or-later. See [LICENSE](LICENSE). Tesseract.js is Apache-2.0, the
+English trained data package is MIT, and jsPDF is MIT; release artifacts include
+the complete generated runtime licence inventory.

SECURITY.md

@@ -0,0 +1,3 @@
+# Security
+
+Please report vulnerabilities privately to the repository owner. Do not attach sensitive source files to public issues. Imported images and recognized text are untrusted; decoder, pixel and page limits must remain bounded, outputs must remain inert, and the OCR runtime/model must stay pinned and same-origin.

SOURCE.md

@@ -0,0 +1,7 @@
+# Corresponding source
+
+The corresponding source for Scan Tools 0.1.0 is available at:
+
+https://git.add-ideas.de/lotobo/scan-tools/src/tag/v0.1.0
+
+Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.

THIRD_PARTY_NOTICES.md

@@ -0,0 +1,16 @@
+# Third-party notices
+
+Scan Tools 0.1.0 directly depends on these runtime packages:
+
+| Package                          | Pinned version | Declared licence |
+| -------------------------------- | -------------: | ---------------- |
+| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-helpers`     |          0.1.0 | GPL-3.0-or-later |
+| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0       |
+| `@tesseract.js-data/eng`         |          1.0.0 | MIT              |
+| `jspdf`                          |          4.2.1 | MIT              |
+| `react`                          |         19.2.8 | MIT              |
+| `react-dom`                      |         19.2.8 | MIT              |
+| `tesseract.js`                   |          7.0.0 | Apache-2.0       |
+
+This table covers direct production dependencies, not transitive packages or development tooling. During a release build, the exact non-development dependency tree and discovered licence texts are generated from the lockfile into `LICENSES/npm-runtime-licenses.txt` and included in the release ZIP. Copyright and licence terms remain with their respective authors.

docs/ACCESSIBILITY.md

@@ -0,0 +1,15 @@
+# Accessibility
+
+Every control has a native label and every operation is available without
+precision pointer input. The four graphical corner handles are focusable sliders:
+arrow keys move by 0.2 percent and Shift+arrow moves by 1 percent. Their values
+are announced as horizontal and vertical percentages. Source and processed
+views have accessible names, while status, errors and OCR progress use live
+native semantics.
+
+Page cards are clickable and preserve document order; drag and drop is a
+convenience rather than a prerequisite because files can be added in order and
+removed individually. Controls retain visible focus. Layouts collapse into
+document order on narrow screens, large hit areas are used, colour is never the
+only status cue, and reduced-motion plus shared system/light/dark themes are
+supported.

docs/ARCHITECTURE.md

@@ -0,0 +1,26 @@
+# Architecture
+
+The React workbench owns an in-memory ordered list of source `File` objects and
+serializable page settings. No page content enters local storage. Each source is
+decoded with `createImageBitmap`; its dimensions and byte size are checked before
+it joins the workspace.
+
+The renderer downscales exceptionally large source rasters to a 24-megapixel
+working ceiling. A projective map sends every destination pixel through the four
+selected source corners and samples it bilinearly. A bounded pixel pass applies
+brightness, contrast, perceptual grayscale and optional Otsu/manual threshold.
+Canvas rotation handles quarter turns and the final ±5 degree deskew. Preview,
+OCR and export call the same renderer with different disclosed pixel budgets, so
+the preview semantics match the downloaded result.
+
+Deskew estimation downsamples to at most 420 pixels on the long edge, tests
+half-degree candidates from −5 to +5, and scores the horizontal projection of
+dark pixels. It declines to invent an angle when insufficient foreground exists.
+
+PDF export dynamically loads jsPDF, renders pages sequentially, JPEG-encodes
+each bounded page, and fits it into the selected physical page. OCR dynamically
+loads Tesseract.js only after user confirmation. Its worker, three LSTM-only
+runtime variants and English integer trained data are copied from pinned npm
+packages to same-origin release assets. Tesseract's persistent model cache is
+disabled, one in-memory worker is reused and can be terminated, and no fallback
+CDN path is used.

docs/PRIVACY-SECURITY.md

@@ -0,0 +1,25 @@
+# Privacy and security
+
+Source files, decoded rasters, page settings and OCR text remain in browser
+memory. There is no upload, telemetry, analytics, account, remote model, remote
+font or external resource lookup. Production policy restricts connections to the
+same origin, permits only same-origin/blob workers, and allows WebAssembly while
+disabling object embedding. Browser tests reject unexpected HTTP requests.
+
+Images are treated as untrusted. Compressed byte size, decoded pixel count, page
+count, working-raster size and all output sizes are bounded. Active SVG is not an
+advertised input and only the browser's raster decoders are accepted. The
+projective transform rejects non-convex, tiny and degenerate corner selections.
+Page rendering is sequential for PDF export to reduce peak memory.
+
+OCR is isolated in the upstream Tesseract.js worker and is not initialized until
+the user acknowledges its memory cost. Worker, core and language URLs are
+constructed relative to the application base; the application never silently
+falls back to the upstream CDN. Tesseract's IndexedDB model cache is disabled;
+the ordinary PWA response cache may retain the same-origin public model file.
+Cancellation terminates the worker. OCR text is untrusted text and is displayed
+only through a text area, never as HTML.
+
+PDFs are image-only. No claim is made that visible metadata, faces, signatures
+or other sensitive page content has been removed. Export is always an explicit
+user action.

eslint.config.mjs

@@ -0,0 +1,38 @@
+import js from "@eslint/js";
+import globals from "globals";
+import reactHooks from "eslint-plugin-react-hooks";
+import reactRefresh from "eslint-plugin-react-refresh";
+import tseslint from "typescript-eslint";
+
+export default tseslint.config(
+  {
+    ignores: [
+      "dist",
+      "release",
+      "coverage",
+      "test-results",
+      "playwright-report",
+      "public/ocr",
+    ],
+  },
+  {
+    extends: [js.configs.recommended, ...tseslint.configs.recommended],
+    files: ["**/*.{ts,tsx}"],
+    languageOptions: {
+      ecmaVersion: 2023,
+      globals: { ...globals.browser, ...globals.worker },
+    },
+    plugins: { "react-hooks": reactHooks, "react-refresh": reactRefresh },
+    rules: {
+      ...reactHooks.configs.recommended.rules,
+      "react-refresh/only-export-components": [
+        "warn",
+        { allowConstantExport: true },
+      ],
+    },
+  },
+  {
+    files: ["scripts/**/*.mjs", "playwright.config.ts"],
+    languageOptions: { globals: globals.node },
+  },
+);

index.html

@@ -0,0 +1,19 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <meta
+      name="description"
+      content="Correct, assemble, recognize and export scanned pages locally."
+    />
+    <link rel="icon" type="image/svg+xml" href="./favicon.svg" />
+    <link rel="manifest" href="./manifest.webmanifest" />
+    <meta name="theme-color" content="#29255f" />
+    <title>Scan Tools</title>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="./src/main.tsx"></script>
+  </body>
+</html>

package.json

@@ -0,0 +1,75 @@
+{
+  "name": "scan-tools",
+  "version": "0.1.0",
+  "description": "Correct, assemble, recognize and export scanned pages locally in the browser.",
+  "license": "GPL-3.0-or-later",
+  "author": "Albrecht Degering",
+  "repository": {
+    "type": "git",
+    "url": "git+https://git.add-ideas.de/lotobo/scan-tools.git"
+  },
+  "homepage": "https://git.add-ideas.de/lotobo/scan-tools",
+  "bugs": {
+    "url": "https://git.add-ideas.de/lotobo/scan-tools/issues"
+  },
+  "private": true,
+  "type": "module",
+  "engines": {
+    "node": ">=22"
+  },
+  "scripts": {
+    "predev": "npm run ocr:prepare && npm run manifest:generate",
+    "dev": "vite",
+    "prebuild": "npm run release:prepare && npm run ocr:prepare && npm run manifest:generate",
+    "build": "tsc -b && vite build",
+    "preview": "vite preview",
+    "typecheck": "tsc -b --pretty false",
+    "lint": "eslint . --max-warnings=0",
+    "format": "prettier --write .",
+    "format:check": "prettier --check .",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:browser": "playwright test",
+    "manifest:generate": "node scripts/generate-toolbox-manifest.mjs",
+    "manifest:check": "node scripts/generate-toolbox-manifest.mjs --check",
+    "release:prepare": "node scripts/prepare-release-files.mjs",
+    "toolbox:check": "toolbox-check dist",
+    "package:release": "node scripts/package-release.mjs",
+    "check": "npm run manifest:check && npm run typecheck && npm run lint && npm run format:check && npm run test && npm run build && npm run toolbox:check",
+    "release:artifact": "npm run check && npm run test:browser && npm run package:release -- --force",
+    "ocr:prepare": "node scripts/prepare-ocr-assets.mjs"
+  },
+  "dependencies": {
+    "@add-ideas/toolbox-contract": "0.2.3",
+    "@add-ideas/toolbox-helpers": "0.1.0",
+    "@add-ideas/toolbox-shell-react": "0.2.3",
+    "@tesseract.js-data/eng": "1.0.0",
+    "jspdf": "4.2.1",
+    "react": "19.2.8",
+    "react-dom": "19.2.8",
+    "tesseract.js": "7.0.0"
+  },
+  "devDependencies": {
+    "@add-ideas/toolbox-testkit": "0.2.3",
+    "@eslint/js": "10.0.1",
+    "@playwright/test": "1.62.1",
+    "@testing-library/jest-dom": "6.9.1",
+    "@testing-library/react": "16.3.2",
+    "@testing-library/user-event": "14.6.1",
+    "@types/node": "25.9.5",
+    "@types/react": "19.2.17",
+    "@types/react-dom": "19.2.5",
+    "@vitejs/plugin-react": "6.0.3",
+    "eslint": "10.7.0",
+    "eslint-plugin-react-hooks": "7.1.1",
+    "eslint-plugin-react-refresh": "0.5.2",
+    "globals": "17.7.0",
+    "jsdom": "29.1.1",
+    "prettier": "3.9.5",
+    "typescript": "6.0.3",
+    "typescript-eslint": "8.64.0",
+    "vite": "8.2.2",
+    "vitest": "4.1.11"
+  },
+  "packageManager": "npm@11.17.0"
+}

playwright.config.ts

@@ -0,0 +1,21 @@
+import { defineConfig, devices } from "@playwright/test";
+
+export default defineConfig({
+  testDir: "./tests/browser",
+  fullyParallel: false,
+  workers: 1,
+  timeout: 120_000,
+  expect: { timeout: 10_000 },
+  reporter: [["list"]],
+  use: { baseURL: "http://127.0.0.1:4203", trace: "retain-on-failure" },
+  webServer: {
+    command: "npm run build && node scripts/serve-test.mjs",
+    url: "http://127.0.0.1:4203",
+    reuseExistingServer: !process.env.CI,
+    timeout: 180_000,
+  },
+  projects: [
+    { name: "chromium", use: { ...devices["Desktop Chrome"] } },
+    { name: "firefox", use: { ...devices["Desktop Firefox"] } },
+  ],
+});

public/CHANGELOG.md

@@ -0,0 +1,14 @@
+# Changelog
+
+## 0.1.0 - 2026-09-01
+
+- Add bounded multi-image and camera-picker ingestion with real decoded-pixel checks
+- Add draggable four-corner projective correction and keyboard-accessible handles
+- Add rotation, manual and estimated deskew, brightness, contrast, grayscale,
+  Otsu threshold and manual threshold processing
+- Add retained debounced previews and bounded high-resolution PNG/JPEG exports
+- Add drag-to-reorder page assembly and A4, Letter, or source-sized PDF output
+- Add opt-in local English OCR using bundled same-origin Tesseract.js runtime and model
+- Add editable OCR text export, explicit confidence and memory/accuracy disclosures
+- Add Toolbox shell integration, nested-path offline PWA support, documentation,
+  deterministic packaging, and Chromium/Firefox coverage

public/CONTRIBUTING.md

@@ -0,0 +1,3 @@
+# Contributing
+
+Run `npm ci`, `npm run check`, and `npm run test:browser` before proposing a change. Keep processing local, preserve explicit byte/pixel/page limits, test transforms with generated non-sensitive images, and never add a silent remote OCR fallback.

public/LICENSE

@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  To protect your rights, we need to prevent others from denying you
+these rights or asking you to surrender the rights.  Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must pass on to the recipients the same
+freedoms that you received.  You must make sure that they, too, receive
+or can get the source code.  And you must show them these terms so they
+know their rights.
+
+  Developers that use the GNU GPL protect your rights with two steps:
+(1) assert copyright on the software, and (2) offer you this License
+giving you legal permission to copy, distribute and/or modify it.
+
+  For the developers' and authors' protection, the GPL clearly explains
+that there is no warranty for this free software.  For both users' and
+authors' sake, the GPL requires that modified versions be marked as
+changed, so that their problems will not be attributed erroneously to
+authors of previous versions.
+
+  Some devices are designed to deny users access to install or run
+modified versions of the software inside them, although the manufacturer
+can do so.  This is fundamentally incompatible with the aim of
+protecting users' freedom to change the software.  The systematic
+pattern of such abuse occurs in the area of products for individuals to
+use, which is precisely where it is most unacceptable.  Therefore, we
+have designed this version of the GPL to prohibit the practice for those
+products.  If such problems arise substantially in other domains, we
+stand ready to extend this provision to those domains in future versions
+of the GPL, as needed to protect the freedom of users.
+
+  Finally, every program is threatened constantly by software patents.
+States should not allow patents to restrict development and use of
+software on general-purpose computers, but in those that do, we wish to
+avoid the special danger that patents applied to a free program could
+make it effectively proprietary.  To prevent this, the GPL assures that
+patents cannot be used to render the program non-free.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
+
+  "This License" refers to version 3 of the GNU General Public License.
+
+  "Copyright" also means copyright-like laws that apply to other kinds of
+works, such as semiconductor masks.
+
+  "The Program" refers to any copyrightable work licensed under this
+License.  Each licensee is addressed as "you".  "Licensees" and
+"recipients" may be individuals or organizations.
+
+  To "modify" a work means to copy from or adapt all or part of the work
+in a fashion requiring copyright permission, other than the making of an
+exact copy.  The resulting work is called a "modified version" of the
+earlier work or a work "based on" the earlier work.
+
+  A "covered work" means either the unmodified Program or a work based
+on the Program.
+
+  To "propagate" a work means to do anything with it that, without
+permission, would make you directly or secondarily liable for
+infringement under applicable copyright law, except executing it on a
+computer or modifying a private copy.  Propagation includes copying,
+distribution (with or without modification), making available to the
+public, and in some countries other activities as well.
+
+  To "convey" a work means any kind of propagation that enables other
+parties to make or receive copies.  Mere interaction with a user through
+a computer network, with no transfer of a copy, is not conveying.
+
+  An interactive user interface displays "Appropriate Legal Notices"
+to the extent that it includes a convenient and prominently visible
+feature that (1) displays an appropriate copyright notice, and (2)
+tells the user that there is no warranty for the work (except to the
+extent that warranties are provided), that licensees may convey the
+work under this License, and how to view a copy of this License.  If
+the interface presents a list of user commands or options, such as a
+menu, a prominent item in the list meets this criterion.
+
+  1. Source Code.
+
+  The "source code" for a work means the preferred form of the work
+for making modifications to it.  "Object code" means any non-source
+form of a work.
+
+  A "Standard Interface" means an interface that either is an official
+standard defined by a recognized standards body, or, in the case of
+interfaces specified for a particular programming language, one that
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+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
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public/LICENSES/README.md

@@ -0,0 +1,3 @@
+# Licences
+
+The application is GPL-3.0-or-later. Generated release artifacts include an exact runtime dependency licence inventory in `npm-runtime-licenses.txt`.

public/README.md

@@ -0,0 +1,62 @@
+# Scan Tools
+
+Correct photographed document pages, assemble them, optionally recognize
+English text, and export images or PDFs without sending content away. Scan
+Tools is a local-first module in the add·ideas Toolbox.
+
+## v0.1.0 capabilities
+
+- Add up to 24 browser-decodable PNG, JPEG or WebP images through a file or
+  camera-enabled picker
+- Drag four document corners to apply an actual projective correction; handles
+  also support keyboard movement
+- Rotate in quarter turns, adjust deskew manually, or estimate a text-line
+  correction within ±5 degrees
+- Tune brightness and contrast, retain colour, convert to grayscale, or create
+  black-and-white pages using Otsu or a manual threshold
+- Preserve the previous preview until its debounced replacement is ready
+- Reorder pages with drag and drop, remove them without touching source files,
+  and export the selected page as PNG or JPEG
+- Assemble every corrected page into A4, US Letter, or source-sized image-only
+  PDFs with a configurable margin
+- Run optional English OCR using a bundled integer model and same-origin
+  Tesseract.js WebAssembly runtime; edit and download recognized text
+- Work at nested paths, install as an offline PWA, use the shared system/light/
+  dark themes, and perform no remote content request
+
+## Honest scope and limits
+
+This first release does not automatically detect page corners, remove fingers
+or shadows, process input PDFs, recognize handwriting reliably, or create a
+searchable invisible PDF text layer. OCR confidence is engine evidence, not an
+accuracy guarantee. Perspective correction is high-quality bilinear resampling;
+each new render is lossy unless exported as PNG.
+
+There are explicit limits of 24 pages, 32 MiB and 80 decoded megapixels per
+source image, 24 megapixels for a working source raster, 1.2 megapixels for an
+interactive preview, 10 megapixels per exported page, and 4 megapixels for OCR.
+Optional OCR loads only after confirmation and may use roughly 100–300 MiB of
+transient memory. The bundled model is English only.
+
+Files, decoded pixels, correction settings and OCR text live in memory. The
+same-origin OCR files are included in the release rather than downloaded from a
+CDN. Nothing is uploaded, but an exported image or PDF naturally contains the
+visible page and an exported text file contains the recognized text.
+
+## Development
+
+```sh
+npm ci
+npm run check
+npm run test:browser
+```
+
+`npm run release:artifact` produces a deterministic ZIP and SHA-256 sidecar.
+The build copies pinned OCR assets from installed npm packages into the static
+release; generated `public/ocr/` content is not source-controlled.
+
+## License
+
+GPL-3.0-or-later. See [LICENSE](LICENSE). Tesseract.js is Apache-2.0, the
+English trained data package is MIT, and jsPDF is MIT; release artifacts include
+the complete generated runtime licence inventory.

public/SECURITY.md

@@ -0,0 +1,3 @@
+# Security
+
+Please report vulnerabilities privately to the repository owner. Do not attach sensitive source files to public issues. Imported images and recognized text are untrusted; decoder, pixel and page limits must remain bounded, outputs must remain inert, and the OCR runtime/model must stay pinned and same-origin.

public/SOURCE.md

@@ -0,0 +1,7 @@
+# Corresponding source
+
+The corresponding source for Scan Tools 0.1.0 is available at:
+
+https://git.add-ideas.de/lotobo/scan-tools/src/tag/v0.1.0
+
+Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.

public/THIRD_PARTY_NOTICES.md

@@ -0,0 +1,16 @@
+# Third-party notices
+
+Scan Tools 0.1.0 directly depends on these runtime packages:
+
+| Package                          | Pinned version | Declared licence |
+| -------------------------------- | -------------: | ---------------- |
+| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-helpers`     |          0.1.0 | GPL-3.0-or-later |
+| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0       |
+| `@tesseract.js-data/eng`         |          1.0.0 | MIT              |
+| `jspdf`                          |          4.2.1 | MIT              |
+| `react`                          |         19.2.8 | MIT              |
+| `react-dom`                      |         19.2.8 | MIT              |
+| `tesseract.js`                   |          7.0.0 | Apache-2.0       |
+
+This table covers direct production dependencies, not transitive packages or development tooling. During a release build, the exact non-development dependency tree and discovered licence texts are generated from the lockfile into `LICENSES/npm-runtime-licenses.txt` and included in the release ZIP. Copyright and licence terms remain with their respective authors.

public/docs/ACCESSIBILITY.md

@@ -0,0 +1,15 @@
+# Accessibility
+
+Every control has a native label and every operation is available without
+precision pointer input. The four graphical corner handles are focusable sliders:
+arrow keys move by 0.2 percent and Shift+arrow moves by 1 percent. Their values
+are announced as horizontal and vertical percentages. Source and processed
+views have accessible names, while status, errors and OCR progress use live
+native semantics.
+
+Page cards are clickable and preserve document order; drag and drop is a
+convenience rather than a prerequisite because files can be added in order and
+removed individually. Controls retain visible focus. Layouts collapse into
+document order on narrow screens, large hit areas are used, colour is never the
+only status cue, and reduced-motion plus shared system/light/dark themes are
+supported.

public/docs/ARCHITECTURE.md

@@ -0,0 +1,26 @@
+# Architecture
+
+The React workbench owns an in-memory ordered list of source `File` objects and
+serializable page settings. No page content enters local storage. Each source is
+decoded with `createImageBitmap`; its dimensions and byte size are checked before
+it joins the workspace.
+
+The renderer downscales exceptionally large source rasters to a 24-megapixel
+working ceiling. A projective map sends every destination pixel through the four
+selected source corners and samples it bilinearly. A bounded pixel pass applies
+brightness, contrast, perceptual grayscale and optional Otsu/manual threshold.
+Canvas rotation handles quarter turns and the final ±5 degree deskew. Preview,
+OCR and export call the same renderer with different disclosed pixel budgets, so
+the preview semantics match the downloaded result.
+
+Deskew estimation downsamples to at most 420 pixels on the long edge, tests
+half-degree candidates from −5 to +5, and scores the horizontal projection of
+dark pixels. It declines to invent an angle when insufficient foreground exists.
+
+PDF export dynamically loads jsPDF, renders pages sequentially, JPEG-encodes
+each bounded page, and fits it into the selected physical page. OCR dynamically
+loads Tesseract.js only after user confirmation. Its worker, three LSTM-only
+runtime variants and English integer trained data are copied from pinned npm
+packages to same-origin release assets. Tesseract's persistent model cache is
+disabled, one in-memory worker is reused and can be terminated, and no fallback
+CDN path is used.

public/docs/PRIVACY-SECURITY.md

@@ -0,0 +1,25 @@
+# Privacy and security
+
+Source files, decoded rasters, page settings and OCR text remain in browser
+memory. There is no upload, telemetry, analytics, account, remote model, remote
+font or external resource lookup. Production policy restricts connections to the
+same origin, permits only same-origin/blob workers, and allows WebAssembly while
+disabling object embedding. Browser tests reject unexpected HTTP requests.
+
+Images are treated as untrusted. Compressed byte size, decoded pixel count, page
+count, working-raster size and all output sizes are bounded. Active SVG is not an
+advertised input and only the browser's raster decoders are accepted. The
+projective transform rejects non-convex, tiny and degenerate corner selections.
+Page rendering is sequential for PDF export to reduce peak memory.
+
+OCR is isolated in the upstream Tesseract.js worker and is not initialized until
+the user acknowledges its memory cost. Worker, core and language URLs are
+constructed relative to the application base; the application never silently
+falls back to the upstream CDN. Tesseract's IndexedDB model cache is disabled;
+the ordinary PWA response cache may retain the same-origin public model file.
+Cancellation terminates the worker. OCR text is untrusted text and is displayed
+only through a text area, never as HTML.
+
+PDFs are image-only. No claim is made that visible metadata, faces, signatures
+or other sensitive page content has been removed. Export is always an explicit
+user action.

public/favicon.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" role="img" aria-label="Scan Tools"><path fill="#176c63" d="M11 4h30l12 12v44H11z"/><path fill="#fff" opacity=".3" d="M41 4v14h12"/><path d="M18 23v-5h7m14 0h7v5M18 42v6h7m14 0h7v-6" fill="none" stroke="#fff" stroke-width="4" stroke-linecap="round"/><path d="M18 33h28" stroke="#8ff5df" stroke-width="4"/><path d="M23 27h18M23 39h18" stroke="#fff" stroke-width="2"/></svg>

public/manifest.webmanifest

@@ -0,0 +1,18 @@
+{
+  "name": "Scan Tools",
+  "short_name": "Scan Tools",
+  "description": "Correct, assemble, recognize and export scanned pages locally.",
+  "start_url": "./",
+  "scope": "./",
+  "display": "standalone",
+  "background_color": "#f6f7fb",
+  "theme_color": "#176c63",
+  "icons": [
+    {
+      "src": "./favicon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "any maskable"
+    }
+  ]
+}

public/sw.js

@@ -0,0 +1,54 @@
+const CACHE_PREFIX = "scan-tools-shell-";
+const CACHE_NAME = CACHE_PREFIX + "0.1.0";
+const CORE = ["./", "./manifest.webmanifest", "./favicon.svg"];
+self.addEventListener("install", (event) => {
+  event.waitUntil(
+    caches.open(CACHE_NAME).then(async (cache) => {
+      await cache.addAll(CORE);
+      const html = await (await fetch("./")).text();
+      const assets = [...html.matchAll(/(?:src|href)="(\.\/assets\/[^"]+)"/g)]
+        .map((match) => match[1])
+        .filter(Boolean);
+      await cache.addAll(assets);
+    }),
+  );
+  self.skipWaiting();
+});
+self.addEventListener("activate", (event) => {
+  event.waitUntil(
+    caches
+      .keys()
+      .then((keys) =>
+        Promise.all(
+          keys
+            .filter((key) => key.startsWith(CACHE_PREFIX) && key !== CACHE_NAME)
+            .map((key) => caches.delete(key)),
+        ),
+      )
+      .then(() => self.clients.claim()),
+  );
+});
+self.addEventListener("fetch", (event) => {
+  if (event.request.method !== "GET") return;
+  const url = new URL(event.request.url);
+  if (
+    url.origin !== self.location.origin ||
+    !url.pathname.startsWith(new URL(self.registration.scope).pathname)
+  )
+    return;
+  event.respondWith(
+    caches.match(event.request).then(
+      (cached) =>
+        cached ??
+        fetch(event.request).then((response) => {
+          if (response.ok) {
+            const copy = response.clone();
+            void caches
+              .open(CACHE_NAME)
+              .then((cache) => cache.put(event.request, copy));
+          }
+          return response;
+        }),
+    ),
+  );
+});

public/toolbox-app.json

@@ -0,0 +1,41 @@
+{
+  "$schema": "https://git.add-ideas.de/lotobo/toolbox-sdk/raw/branch/main/schemas/toolbox-app.v1.schema.json",
+  "schemaVersion": 1,
+  "id": "de.add-ideas.scan-tools",
+  "name": "Scan Tools",
+  "version": "0.1.0",
+  "description": "Correct, assemble, recognize and export scanned pages locally.",
+  "entry": "./",
+  "icon": "./favicon.svg",
+  "categories": ["document", "image", "productivity"],
+  "tags": ["scan", "camera", "deskew", "perspective", "ocr", "pdf"],
+  "integration": {
+    "contextVersion": 1,
+    "launchModes": ["navigate", "new-tab"],
+    "embedding": "unsupported"
+  },
+  "requirements": {
+    "secureContext": false,
+    "workers": true,
+    "indexedDb": false,
+    "crossOriginIsolated": false,
+    "topLevelContext": false
+  },
+  "privacy": {
+    "processing": "local",
+    "fileUploads": true,
+    "telemetry": false,
+    "label": "Page images, corrected pixels and OCR text stay in this browser; nothing is uploaded."
+  },
+  "source": {
+    "repository": "https://git.add-ideas.de/lotobo/scan-tools",
+    "license": "GPL-3.0-or-later"
+  },
+  "actions": [
+    {
+      "id": "source",
+      "label": "Source",
+      "url": "https://git.add-ideas.de/lotobo/scan-tools"
+    }
+  ]
+}

scripts/generate-toolbox-manifest.mjs

@@ -0,0 +1,33 @@
+import { readFile, writeFile } from "node:fs/promises";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { format } from "prettier";
+const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
+const sourcePath = path.join(root, "src/toolbox/manifest.source.json");
+const outputPath = path.join(root, "public/toolbox-app.json");
+const source = JSON.parse(await readFile(sourcePath, "utf8"));
+const pkg = JSON.parse(await readFile(path.join(root, "package.json"), "utf8"));
+const versionSource = await readFile(path.join(root, "src/version.ts"), "utf8");
+const appVersion = /^export const APP_VERSION = "([^"]+)";$/mu.exec(
+  versionSource,
+)?.[1];
+const repository = "https://git.add-ideas.de/lotobo/" + pkg.name;
+if (source.version !== pkg.version || appVersion !== pkg.version)
+  throw new Error("Version identity drift");
+if (
+  source.id !== "de.add-ideas." + pkg.name ||
+  source.source?.repository !== repository ||
+  source.source?.license !== "GPL-3.0-or-later"
+)
+  throw new Error("Manifest source identity is invalid");
+const serialized = await format(JSON.stringify(source), {
+  filepath: outputPath,
+});
+if (process.argv.includes("--check")) {
+  if ((await readFile(outputPath, "utf8").catch(() => "")) !== serialized)
+    throw new Error("public/toolbox-app.json is stale");
+  console.log("Toolbox manifest is synchronized");
+} else {
+  await writeFile(outputPath, serialized);
+  console.log("Generated public/toolbox-app.json");
+}

scripts/package-release.mjs

@@ -0,0 +1,170 @@
+#!/usr/bin/env node
+import { createHash } from "node:crypto";
+import { execFile } from "node:child_process";
+import {
+  access,
+  chmod,
+  copyFile,
+  cp,
+  lstat,
+  mkdir,
+  mkdtemp,
+  readFile,
+  readdir,
+  rename,
+  rm,
+  utimes,
+  writeFile,
+} from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { promisify } from "node:util";
+import { fileURLToPath } from "node:url";
+const execute = promisify(execFile);
+const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
+const pkg = JSON.parse(await readFile(path.join(root, "package.json"), "utf8"));
+const argument = (name, fallback) => {
+  const index = process.argv.indexOf(name);
+  return index >= 0 ? process.argv[index + 1] : fallback;
+};
+const output = path.resolve(
+  root,
+  argument("--output", "release/" + pkg.name + "-" + pkg.version + ".zip"),
+);
+const checksumOutput = output + ".sha256";
+const force = process.argv.includes("--force");
+if (
+  path.extname(output).toLowerCase() !== ".zip" ||
+  output === root ||
+  output === path.parse(output).root
+)
+  throw new Error("Unsafe release target");
+const exists = (file) =>
+  access(file).then(
+    () => true,
+    () => false,
+  );
+if (!force && ((await exists(output)) || (await exists(checksumOutput))))
+  throw new Error("Release output exists");
+const input = path.join(root, "dist");
+for (const name of [
+  "index.html",
+  "manifest.webmanifest",
+  "sw.js",
+  "toolbox-app.json",
+  "favicon.svg",
+  "ocr/worker.min.js",
+  "ocr/core/tesseract-core-lstm.wasm.js",
+  "ocr/core/tesseract-core-simd-lstm.wasm.js",
+  "ocr/core/tesseract-core-relaxedsimd-lstm.wasm.js",
+  "ocr/lang/eng.traineddata.gz",
+  "README.md",
+  "CHANGELOG.md",
+  "CONTRIBUTING.md",
+  "LICENSE",
+  "SECURITY.md",
+  "SOURCE.md",
+  "THIRD_PARTY_NOTICES.md",
+  "LICENSES/README.md",
+  "LICENSES/npm-runtime-licenses.txt",
+  "docs/ACCESSIBILITY.md",
+  "docs/ARCHITECTURE.md",
+  "docs/PRIVACY-SECURITY.md",
+]) {
+  const details = await lstat(path.join(input, name)).catch(() => null);
+  if (!details?.isFile() || details.isSymbolicLink())
+    throw new Error("Missing release file: " + name);
+}
+const manifest = JSON.parse(
+  await readFile(path.join(input, "toolbox-app.json"), "utf8"),
+);
+const repository = "https://git.add-ideas.de/lotobo/" + pkg.name;
+if (
+  manifest.id !== "de.add-ideas." + pkg.name ||
+  manifest.version !== pkg.version ||
+  manifest.entry !== "./" ||
+  manifest.icon !== "./favicon.svg" ||
+  manifest.source?.repository !== repository
+)
+  throw new Error("Packaged manifest identity is invalid");
+if (
+  /\b(?:src|href)=["']\//iu.test(
+    await readFile(path.join(input, "index.html"), "utf8"),
+  )
+)
+  throw new Error("Root-absolute asset reference");
+async function collect(directory, prefix = "") {
+  const files = [];
+  for (const entry of (await readdir(directory, { withFileTypes: true })).sort(
+    (a, b) => a.name.localeCompare(b.name),
+  )) {
+    const absolute = path.join(directory, entry.name);
+    const relative = prefix ? prefix + "/" + entry.name : entry.name;
+    if (entry.isSymbolicLink())
+      throw new Error("Symlink in release: " + relative);
+    if (entry.isDirectory()) files.push(...(await collect(absolute, relative)));
+    else if (entry.isFile()) files.push({ absolute, relative });
+    else throw new Error("Unsupported release entry: " + relative);
+  }
+  return files;
+}
+const sourceFiles = await collect(input);
+for (const file of sourceFiles)
+  if (
+    file.relative.endsWith(".map") ||
+    /(?:^|\/)(?:\.env(?:\.|$)|id_rsa|id_ed25519|.*\.pem$|.*\.key$)/iu.test(
+      file.relative,
+    ) ||
+    file.relative.split("/").includes("..")
+  )
+    throw new Error("Forbidden release entry: " + file.relative);
+await mkdir(path.dirname(output), { recursive: true });
+const stagingRoot = await mkdtemp(
+  path.join(os.tmpdir(), pkg.name + "-release-"),
+);
+const publicationRoot = await mkdtemp(
+  path.join(path.dirname(output), "." + pkg.name + "-publish-"),
+);
+const stagedTree = path.join(stagingRoot, "tree");
+const stagedArchive = path.join(stagingRoot, path.basename(output));
+try {
+  await cp(input, stagedTree, { recursive: true });
+  const timestamp = new Date("1980-01-01T00:00:00.000Z");
+  for (const file of await collect(stagedTree)) {
+    await chmod(file.absolute, 0o644);
+    await utimes(file.absolute, timestamp, timestamp);
+  }
+  await execute(
+    "zip",
+    [
+      "-X",
+      "-q",
+      "-9",
+      stagedArchive,
+      ...sourceFiles.map((file) => file.relative),
+    ],
+    {
+      cwd: stagedTree,
+      env: { ...process.env, TZ: "UTC" },
+      maxBuffer: 1024 * 1024,
+    },
+  );
+  const archive = await readFile(stagedArchive);
+  const digest = createHash("sha256").update(archive).digest("hex");
+  const stagedChecksum = stagedArchive + ".sha256";
+  await writeFile(stagedChecksum, digest + "  " + path.basename(output) + "\n");
+  const publicationArchive = path.join(publicationRoot, path.basename(output));
+  const publicationChecksum = publicationArchive + ".sha256";
+  await copyFile(stagedArchive, publicationArchive);
+  await copyFile(stagedChecksum, publicationChecksum);
+  if (force) {
+    await rm(output, { force: true });
+    await rm(checksumOutput, { force: true });
+  }
+  await rename(publicationArchive, output);
+  await rename(publicationChecksum, checksumOutput);
+  console.log("Created " + path.relative(root, output) + "\nSHA-256 " + digest);
+} finally {
+  await rm(stagingRoot, { recursive: true, force: true });
+  await rm(publicationRoot, { recursive: true, force: true });
+}

scripts/prepare-ocr-assets.mjs

@@ -0,0 +1,35 @@
+import { copyFile, mkdir, rm } from "node:fs/promises";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
+const output = path.join(root, "public", "ocr");
+await rm(output, { recursive: true, force: true });
+await mkdir(path.join(output, "core"), { recursive: true });
+await mkdir(path.join(output, "lang"), { recursive: true });
+
+await copyFile(
+  path.join(root, "node_modules", "tesseract.js", "dist", "worker.min.js"),
+  path.join(output, "worker.min.js"),
+);
+for (const name of [
+  "tesseract-core-lstm.wasm.js",
+  "tesseract-core-simd-lstm.wasm.js",
+  "tesseract-core-relaxedsimd-lstm.wasm.js",
+])
+  await copyFile(
+    path.join(root, "node_modules", "tesseract.js-core", name),
+    path.join(output, "core", name),
+  );
+await copyFile(
+  path.join(
+    root,
+    "node_modules",
+    "@tesseract.js-data",
+    "eng",
+    "4.0.0_best_int",
+    "eng.traineddata.gz",
+  ),
+  path.join(output, "lang", "eng.traineddata.gz"),
+);
+console.log("Prepared same-origin OCR runtime and English model");

scripts/prepare-release-files.mjs

@@ -0,0 +1,70 @@
+import { cp, mkdir, readFile, readdir, rm, writeFile } from "node:fs/promises";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
+const destination = path.join(root, "public");
+for (const name of [
+  "LICENSE",
+  "README.md",
+  "CHANGELOG.md",
+  "CONTRIBUTING.md",
+  "SECURITY.md",
+  "SOURCE.md",
+  "THIRD_PARTY_NOTICES.md",
+]) {
+  await readFile(path.join(root, name));
+  await cp(path.join(root, name), path.join(destination, name));
+}
+for (const directory of ["LICENSES", "docs"]) {
+  const output = path.join(destination, directory);
+  await rm(output, { recursive: true, force: true });
+  await cp(path.join(root, directory), output, { recursive: true });
+}
+const lock = JSON.parse(
+  await readFile(path.join(root, "package-lock.json"), "utf8"),
+);
+const sections = [];
+for (const [location, locked] of Object.entries(lock.packages ?? {}).sort(
+  ([a], [b]) => a.localeCompare(b),
+)) {
+  if (!location.includes("node_modules/") || locked.dev === true) continue;
+  const packageDirectory = path.join(root, location);
+  const details = JSON.parse(
+    await readFile(path.join(packageDirectory, "package.json"), "utf8"),
+  );
+  const candidates = (await readdir(packageDirectory))
+    .filter((name) => /^(?:licen[cs]e|copying|notice)(?:\.|$)/iu.test(name))
+    .sort();
+  const texts = [];
+  for (const candidate of candidates) {
+    try {
+      texts.push(
+        "--- " +
+          candidate +
+          " ---\n" +
+          (await readFile(path.join(packageDirectory, candidate), "utf8")),
+      );
+    } catch {
+      /* directory */
+    }
+  }
+  sections.push(
+    "=".repeat(78) +
+      "\n" +
+      details.name +
+      "@" +
+      details.version +
+      "\nDeclared licence: " +
+      (details.license ?? locked.license ?? "See upstream") +
+      "\n" +
+      "=".repeat(78) +
+      "\n" +
+      (texts.join("\n\n") || "See upstream package metadata."),
+  );
+}
+await mkdir(path.join(destination, "LICENSES"), { recursive: true });
+await writeFile(
+  path.join(destination, "LICENSES/npm-runtime-licenses.txt"),
+  sections.join("\n\n").trimEnd() + "\n",
+);
+console.log("Prepared release documentation");

scripts/serve-test.mjs

@@ -0,0 +1,67 @@
+import { createServer } from "node:http";
+import { readFile, stat } from "node:fs/promises";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+const root = path.resolve(
+  path.dirname(fileURLToPath(import.meta.url)),
+  "..",
+  "dist",
+);
+const prefix = "/deep/nested/scan-tools/";
+const types = new Map([
+  [".css", "text/css; charset=utf-8"],
+  [".html", "text/html; charset=utf-8"],
+  [".js", "text/javascript; charset=utf-8"],
+  [".json", "application/json; charset=utf-8"],
+  [".webmanifest", "application/manifest+json; charset=utf-8"],
+  [".svg", "image/svg+xml"],
+  [".md", "text/markdown; charset=utf-8"],
+  [".txt", "text/plain; charset=utf-8"],
+  [".wasm", "application/wasm"],
+  [".png", "image/png"],
+  [".jpg", "image/jpeg"],
+  [".webp", "image/webp"],
+  [".gz", "application/gzip"],
+]);
+const headers = {
+  "Content-Security-Policy":
+    "default-src 'self'; base-uri 'self'; object-src 'none'; frame-ancestors 'none'; form-action 'self'; script-src 'self' 'wasm-unsafe-eval'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob:; media-src 'self' blob:; connect-src 'self'; worker-src 'self' blob:; manifest-src 'self'",
+  "Cross-Origin-Opener-Policy": "same-origin",
+  "Cross-Origin-Resource-Policy": "same-origin",
+  "Permissions-Policy":
+    "camera=(), microphone=(), geolocation=(), usb=(), payment=()",
+  "Referrer-Policy": "no-referrer",
+  "X-Content-Type-Options": "nosniff",
+};
+const server = createServer(async (request, response) => {
+  try {
+    const url = new URL(request.url ?? "/", "http://127.0.0.1");
+    const relative = decodeURIComponent(url.pathname).startsWith(prefix)
+      ? decodeURIComponent(url.pathname).slice(prefix.length)
+      : decodeURIComponent(url.pathname).replace(/^\/+/, "");
+    const normalized = path.posix.normalize(relative || "index.html");
+    if (
+      normalized === ".." ||
+      normalized.startsWith("../") ||
+      path.isAbsolute(normalized)
+    ) {
+      response.writeHead(400).end("Bad request");
+      return;
+    }
+    let file = path.join(root, normalized);
+    if ((await stat(file).catch(() => null))?.isDirectory())
+      file = path.join(file, "index.html");
+    const content = await readFile(file);
+    response.writeHead(200, {
+      "Content-Type":
+        types.get(path.extname(file)) ?? "application/octet-stream",
+      "Cache-Control": "no-cache",
+      ...headers,
+    });
+    response.end(content);
+  } catch {
+    response.writeHead(404, { "Content-Type": "text/plain; charset=utf-8" });
+    response.end("Not found");
+  }
+});
+server.listen(4203, "127.0.0.1", () => console.log("Test server ready"));

src/App.tsx

@@ -0,0 +1,35 @@
+import { lazy, Suspense, useState } from "react";
+import { AppShell } from "@add-ideas/toolbox-shell-react";
+import "@add-ideas/toolbox-shell-react/styles.css";
+import "./styles.css";
+import { ErrorBoundary } from "./components/ErrorBoundary";
+import { HelpDialog } from "./components/HelpDialog";
+import { manifest } from "./toolbox/manifest";
+
+const Workbench = lazy(async () => ({
+  default: (await import("./components/Workbench")).Workbench,
+}));
+
+export function App() {
+  const [helpOpen, setHelpOpen] = useState(false);
+  return (
+    <ErrorBoundary>
+      <AppShell
+        app={manifest}
+        manifestUrl="./toolbox-app.json"
+        helpAction={{ onClick: () => setHelpOpen(true) }}
+      >
+        <Suspense
+          fallback={
+            <p className="loading" role="status">
+              Preparing Scan Tools…
+            </p>
+          }
+        >
+          <Workbench />
+        </Suspense>
+      </AppShell>
+      <HelpDialog open={helpOpen} onClose={() => setHelpOpen(false)} />
+    </ErrorBoundary>
+  );
+}

src/components/ErrorBoundary.tsx

@@ -0,0 +1,27 @@
+import { Component, type ErrorInfo, type ReactNode } from "react";
+
+export class ErrorBoundary extends Component<
+  { children: ReactNode },
+  { error?: Error }
+> {
+  state: { error?: Error } = {};
+  static getDerivedStateFromError(error: Error) {
+    return { error };
+  }
+  componentDidCatch(error: Error, info: ErrorInfo) {
+    console.error("Application failure", error, info);
+  }
+  render() {
+    if (this.state.error)
+      return (
+        <main className="fatal">
+          <h1>Scan Tools could not continue</h1>
+          <p>{this.state.error.message}</p>
+          <button type="button" onClick={() => location.reload()}>
+            Reload
+          </button>
+        </main>
+      );
+    return this.props.children;
+  }
+}

src/components/HelpDialog.tsx

@@ -0,0 +1,53 @@
+import { useEffect, useRef } from "react";
+
+export function HelpDialog({
+  open,
+  onClose,
+}: {
+  open: boolean;
+  onClose: () => void;
+}) {
+  const dialog = useRef<HTMLDialogElement>(null);
+  useEffect(() => {
+    const node = dialog.current;
+    if (!node) return;
+    if (open && !node.open) node.showModal();
+    if (!open && node.open) node.close();
+  }, [open]);
+  return (
+    <dialog
+      ref={dialog}
+      className="help-dialog"
+      onClose={onClose}
+      onCancel={onClose}
+      aria-labelledby="help-title"
+    >
+      <div className="dialog-heading">
+        <div>
+          <p className="eyebrow">Local-first help</p>
+          <h2 id="help-title">About Scan Tools</h2>
+        </div>
+        <button type="button" onClick={onClose} aria-label="Close help">
+          ×
+        </button>
+      </div>
+      <p>
+        Add PNG, JPEG or WebP page photographs, drag the four corners around the
+        document, then adjust rotation, deskew, brightness, contrast and output
+        style. Page cards can be dragged into PDF order.
+      </p>
+      <p>
+        English OCR is optional and deliberately lazy. Confirm its disclosed
+        memory cost before the bundled language model and WebAssembly engine are
+        loaded. OCR can be inaccurate, especially for handwriting, unusual
+        layouts and low-quality photographs; verify recognized text yourself.
+      </p>
+      <p>
+        Processing is local and no remote services are contacted. The workspace
+        lives only in memory. Exported PDFs are image-only in this release, and
+        automatic corner detection and searchable PDF text layers are not
+        claimed.
+      </p>
+    </dialog>
+  );
+}

src/components/Workbench.tsx

@@ -0,0 +1,841 @@
+import {
+  useEffect,
+  useMemo,
+  useRef,
+  useState,
+  type ChangeEvent,
+  type DragEvent,
+  type PointerEvent as ReactPointerEvent,
+} from "react";
+import { triggerBlobDownload } from "@add-ideas/toolbox-helpers";
+import { buildPdf, exportImage, type PdfPageSize } from "../scan/export";
+import { moveQuadPoint } from "../scan/geometry";
+import { cancelOcr, closeOcr, recognizeEnglish } from "../scan/ocr";
+import {
+  canvasBlob,
+  detectDeskew,
+  inspectImage,
+  renderPage,
+} from "../scan/render";
+import {
+  defaultAdjustments,
+  MAX_PAGE_BYTES,
+  MAX_PAGES,
+  MAX_PREVIEW_PIXELS,
+  type PageAdjustments,
+  type Point,
+  type ScanPage,
+} from "../scan/types";
+
+function pageId(): string {
+  return (
+    crypto.randomUUID?.() ??
+    `${Date.now()}-${Math.random().toString(16).slice(2)}`
+  );
+}
+
+function useObjectUrl(file: File | undefined): string | undefined {
+  const url = useMemo(
+    () => (file ? URL.createObjectURL(file) : undefined),
+    [file],
+  );
+  useEffect(
+    () => () => {
+      if (url) URL.revokeObjectURL(url);
+    },
+    [url],
+  );
+  return url;
+}
+
+function formatBytes(bytes: number): string {
+  return bytes < 1024 * 1024
+    ? `${Math.ceil(bytes / 1024)} KiB`
+    : `${(bytes / 1024 / 1024).toFixed(1)} MiB`;
+}
+
+function SourceCorners({
+  page,
+  update,
+}: {
+  page: ScanPage;
+  update: (adjustments: PageAdjustments) => void;
+}) {
+  const url = useObjectUrl(page.source);
+  const svg = useRef<SVGSVGElement>(null);
+  const [moving, setMoving] = useState<number>();
+  const points = page.adjustments.quad
+    .map((point) => `${point.x * 100},${point.y * 100}`)
+    .join(" ");
+
+  const move = (event: ReactPointerEvent<SVGCircleElement>, index: number) => {
+    if (moving !== index || !svg.current) return;
+    const bounds = svg.current.getBoundingClientRect();
+    const point: Point = {
+      x: (event.clientX - bounds.left) / bounds.width,
+      y: (event.clientY - bounds.top) / bounds.height,
+    };
+    update({
+      ...page.adjustments,
+      quad: moveQuadPoint(page.adjustments.quad, index, point),
+    });
+  };
+
+  return (
+    <section className="preview-card">
+      <h3>Source &amp; document corners</h3>
+      <p className="microcopy">
+        Drag the four numbered handles around the page.
+      </p>
+      <div
+        className="source-stage"
+        style={{ aspectRatio: `${page.width} / ${page.height}` }}
+      >
+        {url ? <img src={url} alt={`Unprocessed ${page.name}`} /> : null}
+        <svg
+          ref={svg}
+          viewBox="0 0 100 100"
+          aria-label="Document corner selection"
+        >
+          <polygon points={points} />
+          {page.adjustments.quad.map((point, index) => (
+            <circle
+              key={index}
+              cx={point.x * 100}
+              cy={point.y * 100}
+              r="2.8"
+              tabIndex={0}
+              role="slider"
+              aria-label={`Corner ${index + 1}`}
+              aria-valuetext={`${Math.round(point.x * 100)}% from left, ${Math.round(point.y * 100)}% from top`}
+              onPointerDown={(event) => {
+                setMoving(index);
+                event.currentTarget.setPointerCapture(event.pointerId);
+              }}
+              onPointerMove={(event) => move(event, index)}
+              onPointerUp={() => setMoving(undefined)}
+              onKeyDown={(event) => {
+                const step = event.shiftKey ? 0.01 : 0.002;
+                const delta =
+                  event.key === "ArrowLeft"
+                    ? { x: -step, y: 0 }
+                    : event.key === "ArrowRight"
+                      ? { x: step, y: 0 }
+                      : event.key === "ArrowUp"
+                        ? { x: 0, y: -step }
+                        : event.key === "ArrowDown"
+                          ? { x: 0, y: step }
+                          : undefined;
+                if (!delta) return;
+                event.preventDefault();
+                update({
+                  ...page.adjustments,
+                  quad: moveQuadPoint(page.adjustments.quad, index, {
+                    x: point.x + delta.x,
+                    y: point.y + delta.y,
+                  }),
+                });
+              }}
+            />
+          ))}
+          {page.adjustments.quad.map((point, index) => (
+            <text
+              key={`label-${index}`}
+              x={point.x * 100}
+              y={point.y * 100 + 1.2}
+            >
+              {index + 1}
+            </text>
+          ))}
+        </svg>
+      </div>
+    </section>
+  );
+}
+
+function ProcessedPreview({ page }: { page: ScanPage }) {
+  const canvasRef = useRef<HTMLCanvasElement>(null);
+  const [state, setState] = useState("Rendering preview…");
+  useEffect(() => {
+    let current = true;
+    const timeout = window.setTimeout(() => {
+      void renderPage(page, MAX_PREVIEW_PIXELS)
+        .then((rendered) => {
+          if (!current || !canvasRef.current) return;
+          const target = canvasRef.current;
+          target.width = rendered.canvas.width;
+          target.height = rendered.canvas.height;
+          target.getContext("2d")?.drawImage(rendered.canvas, 0, 0);
+          setState(
+            `${rendered.canvas.width} × ${rendered.canvas.height}px preview${rendered.sourceScale < 1 || rendered.outputScale < 1 ? " · safely downscaled" : ""}`,
+          );
+        })
+        .catch((reason: unknown) => {
+          if (current)
+            setState(
+              reason instanceof Error ? reason.message : "Preview failed.",
+            );
+        });
+    }, 120);
+    return () => {
+      current = false;
+      window.clearTimeout(timeout);
+    };
+  }, [page]);
+  return (
+    <section className="preview-card">
+      <h3>Processed preview</h3>
+      <p className="microcopy" role="status">
+        {state}
+      </p>
+      <div className="processed-stage">
+        <canvas
+          ref={canvasRef}
+          aria-label={`Processed preview of ${page.name}`}
+        />
+      </div>
+    </section>
+  );
+}
+
+function PageStrip({
+  pages,
+  selected,
+  choose,
+  reorder,
+  remove,
+}: {
+  pages: ScanPage[];
+  selected: string | undefined;
+  choose: (id: string) => void;
+  reorder: (from: string, to: string) => void;
+  remove: (id: string) => void;
+}) {
+  const [dragged, setDragged] = useState<string>();
+  return (
+    <ol className="page-strip" aria-label="Document pages">
+      {pages.map((page, index) => (
+        <li
+          key={page.id}
+          className={selected === page.id ? "selected" : ""}
+          draggable
+          onDragStart={() => setDragged(page.id)}
+          onDragOver={(event: DragEvent) => event.preventDefault()}
+          onDrop={() => {
+            if (dragged && dragged !== page.id) reorder(dragged, page.id);
+            setDragged(undefined);
+          }}
+        >
+          <button
+            type="button"
+            className="page-choice"
+            onClick={() => choose(page.id)}
+          >
+            <strong>Page {index + 1}</strong>
+            <span>{page.name}</span>
+            <small>
+              {page.width} × {page.height}
+              {page.ocrText ? " · OCR" : ""}
+            </small>
+          </button>
+          <span className="drag-hint" aria-hidden="true">
+            ⠿
+          </span>
+          <button
+            type="button"
+            className="icon-button"
+            aria-label={`Remove page ${index + 1}`}
+            onClick={() => remove(page.id)}
+          >
+            ×
+          </button>
+        </li>
+      ))}
+    </ol>
+  );
+}
+
+export function Workbench() {
+  const [pages, setPages] = useState<ScanPage[]>([]);
+  const [selectedId, setSelectedId] = useState<string>();
+  const [error, setError] = useState<string>();
+  const [notice, setNotice] = useState(
+    "Add photographs or image files to begin.",
+  );
+  const [busy, setBusy] = useState(false);
+  const [ocrConsent, setOcrConsent] = useState(false);
+  const [ocrProgress, setOcrProgress] = useState<{
+    status: string;
+    progress: number;
+  }>();
+  const [pdfSize, setPdfSize] = useState<PdfPageSize>("a4");
+  const [pdfMargin, setPdfMargin] = useState(18);
+  const selected = pages.find((page) => page.id === selectedId) ?? pages[0];
+
+  useEffect(
+    () => () => {
+      void closeOcr().catch(() => undefined);
+    },
+    [],
+  );
+  const totalSize = useMemo(
+    () => pages.reduce((sum, page) => sum + page.source.size, 0),
+    [pages],
+  );
+
+  const addFiles = async (event: ChangeEvent<HTMLInputElement>) => {
+    const files = [...(event.target.files ?? [])];
+    event.target.value = "";
+    if (files.length === 0) return;
+    setBusy(true);
+    setError(undefined);
+    const additions: ScanPage[] = [];
+    const failures: string[] = [];
+    try {
+      for (const file of files.slice(
+        0,
+        Math.max(0, MAX_PAGES - pages.length),
+      )) {
+        const extension = file.name.split(".").at(-1)?.toLowerCase();
+        if (
+          !["image/png", "image/jpeg", "image/webp"].includes(file.type) &&
+          !(
+            file.type === "" &&
+            ["png", "jpg", "jpeg", "webp"].includes(extension ?? "")
+          )
+        ) {
+          failures.push(`${file.name}: only PNG, JPEG and WebP are supported`);
+          continue;
+        }
+        if (file.size > MAX_PAGE_BYTES) {
+          failures.push(`${file.name}: exceeds ${formatBytes(MAX_PAGE_BYTES)}`);
+          continue;
+        }
+        try {
+          const dimensions = await inspectImage(file);
+          additions.push({
+            id: pageId(),
+            name: file.name,
+            source: file,
+            ...dimensions,
+            adjustments: defaultAdjustments(),
+          });
+        } catch (reason) {
+          failures.push(
+            `${file.name}: ${reason instanceof Error ? reason.message : "not a supported image"}`,
+          );
+        }
+      }
+      if (files.length > MAX_PAGES - pages.length)
+        failures.push(`Only ${MAX_PAGES} pages are allowed in one workspace.`);
+      setPages((current) => [...current, ...additions]);
+      if (!selectedId && additions[0]) setSelectedId(additions[0].id);
+      setNotice(
+        `${additions.length} page${additions.length === 1 ? "" : "s"} added locally.`,
+      );
+      if (failures.length) setError(failures.join(" "));
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  const updateSelected = (adjustments: PageAdjustments) => {
+    if (!selected) return;
+    setPages((current) =>
+      current.map((page) =>
+        page.id === selected.id ? { ...page, adjustments } : page,
+      ),
+    );
+  };
+  const patchSelected = (patch: Partial<PageAdjustments>) => {
+    if (selected) updateSelected({ ...selected.adjustments, ...patch });
+  };
+
+  const runDeskew = async () => {
+    if (!selected) return;
+    setBusy(true);
+    setError(undefined);
+    setNotice("Estimating text-line angle locally…");
+    try {
+      const angle = await detectDeskew(selected);
+      patchSelected({ deskew: angle });
+      setNotice(
+        angle === 0
+          ? "No reliable skew was detected."
+          : `Applied an estimated ${angle.toFixed(1)}° correction.`,
+      );
+    } catch (reason) {
+      setError(
+        reason instanceof Error ? reason.message : "Deskew estimation failed.",
+      );
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  const exportCurrentImage = async (type: "image/png" | "image/jpeg") => {
+    if (!selected) return;
+    setBusy(true);
+    setError(undefined);
+    setNotice(`Rendering ${type === "image/png" ? "PNG" : "JPEG"} locally…`);
+    try {
+      await exportImage(selected, type);
+      setNotice(
+        `Rendered ${selected.name} within the 10-megapixel export budget.`,
+      );
+    } catch (reason) {
+      setError(
+        `${reason instanceof Error ? reason.message : "Image export failed."} The workspace was retained.`,
+      );
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  const runOcr = async () => {
+    if (!selected || !ocrConsent) return;
+    setBusy(true);
+    setError(undefined);
+    setOcrProgress({ status: "Preparing local OCR", progress: 0 });
+    try {
+      const rendered = await renderPage(selected, 4_000_000);
+      const image = await canvasBlob(rendered.canvas, "image/png");
+      const result = await recognizeEnglish(image, (status, progress) =>
+        setOcrProgress({ status, progress }),
+      );
+      setPages((current) =>
+        current.map((page) =>
+          page.id === selected.id
+            ? {
+                ...page,
+                ocrText: result.text,
+                ocrConfidence: result.confidence,
+              }
+            : page,
+        ),
+      );
+      setNotice(
+        `English OCR finished with ${result.confidence.toFixed(1)}% engine confidence.`,
+      );
+    } catch (reason) {
+      setError(
+        `${reason instanceof Error ? reason.message : "OCR failed."} The page and previous text were retained.`,
+      );
+    } finally {
+      setBusy(false);
+      setOcrProgress(undefined);
+    }
+  };
+
+  const exportPdf = async () => {
+    setBusy(true);
+    setError(undefined);
+    try {
+      const pdf = await buildPdf(
+        pages,
+        pdfSize,
+        pdfMargin,
+        (completed, total) =>
+          setNotice(`Rendering PDF page ${completed} of ${total}…`),
+      );
+      triggerBlobDownload(pdf, "local-scan.pdf");
+      setNotice(`Created a ${formatBytes(pdf.size)} image-only PDF locally.`);
+    } catch (reason) {
+      setError(
+        `${reason instanceof Error ? reason.message : "PDF export failed."} The workspace was retained.`,
+      );
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  return (
+    <main className="workbench">
+      <section className="intro-card">
+        <div>
+          <p className="eyebrow">Local document capture</p>
+          <h2>Correct pages, assemble a document, then export.</h2>
+          <p>
+            Files, pixels and OCR text stay in this browser. Camera access is
+            requested by your device only when you use the camera-enabled
+            picker.
+          </p>
+        </div>
+        <label className="file-button">
+          <span>{busy ? "Working…" : "Add images or camera pages"}</span>
+          <input
+            aria-label="Add images or camera pages"
+            type="file"
+            accept="image/png,image/jpeg,image/webp,image/*"
+            capture="environment"
+            multiple
+            disabled={busy || pages.length >= MAX_PAGES}
+            onChange={(event) => void addFiles(event)}
+          />
+        </label>
+      </section>
+
+      <p className="status-line" role="status">
+        {notice}
+      </p>
+      {error ? (
+        <p className="error" role="alert">
+          {error}
+        </p>
+      ) : null}
+
+      {pages.length === 0 ? (
+        <section className="empty-card">
+          <h2>No pages yet</h2>
+          <p>
+            Supported inputs are browser-decodable PNG, JPEG and WebP images, up
+            to {formatBytes(MAX_PAGE_BYTES)} and 80 megapixels each.
+          </p>
+          <ul>
+            <li>
+              Four-corner perspective correction and manual or automatic deskew
+            </li>
+            <li>Colour, grayscale and automatic/manual threshold modes</li>
+            <li>
+              Drag-to-reorder assembly, local English OCR, image and PDF export
+            </li>
+          </ul>
+        </section>
+      ) : (
+        <div className="workspace-grid">
+          <aside className="pages-card">
+            <div className="section-heading">
+              <div>
+                <p className="eyebrow">Assembly</p>
+                <h2>
+                  {pages.length} / {MAX_PAGES} pages
+                </h2>
+              </div>
+              <small>{formatBytes(totalSize)} source</small>
+            </div>
+            <PageStrip
+              pages={pages}
+              selected={selected?.id}
+              choose={setSelectedId}
+              reorder={(from, to) =>
+                setPages((current) => {
+                  const next = [...current];
+                  const fromIndex = next.findIndex((page) => page.id === from);
+                  const toIndex = next.findIndex((page) => page.id === to);
+                  if (fromIndex < 0 || toIndex < 0) return current;
+                  const [moved] = next.splice(fromIndex, 1);
+                  if (moved) next.splice(toIndex, 0, moved);
+                  return next;
+                })
+              }
+              remove={(id) => {
+                setPages((current) => current.filter((page) => page.id !== id));
+                if (selectedId === id) setSelectedId(undefined);
+              }}
+            />
+            <p className="microcopy">
+              Drag page cards to reorder. Removing a page affects only this
+              in-memory workspace.
+            </p>
+          </aside>
+
+          {selected ? (
+            <section className="editor-card">
+              <div className="section-heading">
+                <div>
+                  <p className="eyebrow">Selected page</p>
+                  <h2>{selected.name}</h2>
+                </div>
+                <div className="button-row">
+                  <button
+                    type="button"
+                    disabled={busy}
+                    onClick={() =>
+                      patchSelected({
+                        quarterTurns: ((selected.adjustments.quarterTurns + 3) %
+                          4) as 0 | 1 | 2 | 3,
+                      })
+                    }
+                  >
+                    Rotate left
+                  </button>
+                  <button
+                    type="button"
+                    disabled={busy}
+                    onClick={() =>
+                      patchSelected({
+                        quarterTurns: ((selected.adjustments.quarterTurns + 1) %
+                          4) as 0 | 1 | 2 | 3,
+                      })
+                    }
+                  >
+                    Rotate right
+                  </button>
+                  <button
+                    type="button"
+                    disabled={busy}
+                    onClick={() => updateSelected(defaultAdjustments())}
+                  >
+                    Reset
+                  </button>
+                </div>
+              </div>
+              <div className="preview-grid">
+                <SourceCorners page={selected} update={updateSelected} />
+                <ProcessedPreview page={selected} />
+              </div>
+              <fieldset className="controls-grid" disabled={busy}>
+                <legend>Page correction</legend>
+                <label>
+                  Output style
+                  <select
+                    value={selected.adjustments.colourMode}
+                    onChange={(event) =>
+                      patchSelected({
+                        colourMode: event.target
+                          .value as PageAdjustments["colourMode"],
+                      })
+                    }
+                  >
+                    <option value="colour">Colour document</option>
+                    <option value="grayscale">Grayscale</option>
+                    <option value="threshold">Black &amp; white</option>
+                  </select>
+                </label>
+                {selected.adjustments.colourMode === "threshold" ? (
+                  <label>
+                    Threshold
+                    <select
+                      value={
+                        selected.adjustments.threshold === "auto"
+                          ? "auto"
+                          : "manual"
+                      }
+                      onChange={(event) =>
+                        patchSelected({
+                          threshold:
+                            event.target.value === "auto" ? "auto" : 150,
+                        })
+                      }
+                    >
+                      <option value="auto">Automatic (Otsu)</option>
+                      <option value="manual">Manual</option>
+                    </select>
+                  </label>
+                ) : null}
+                {typeof selected.adjustments.threshold === "number" &&
+                selected.adjustments.colourMode === "threshold" ? (
+                  <label>
+                    Manual threshold{" "}
+                    <output>{selected.adjustments.threshold}</output>
+                    <input
+                      type="range"
+                      min="20"
+                      max="235"
+                      value={selected.adjustments.threshold}
+                      onChange={(event) =>
+                        patchSelected({ threshold: Number(event.target.value) })
+                      }
+                    />
+                  </label>
+                ) : null}
+                <label>
+                  Brightness <output>{selected.adjustments.brightness}</output>
+                  <input
+                    aria-label="Brightness adjustment"
+                    type="range"
+                    min="-80"
+                    max="80"
+                    value={selected.adjustments.brightness}
+                    onChange={(event) =>
+                      patchSelected({ brightness: Number(event.target.value) })
+                    }
+                  />
+                </label>
+                <label>
+                  Contrast <output>{selected.adjustments.contrast}</output>
+                  <input
+                    aria-label="Contrast adjustment"
+                    type="range"
+                    min="-80"
+                    max="80"
+                    value={selected.adjustments.contrast}
+                    onChange={(event) =>
+                      patchSelected({ contrast: Number(event.target.value) })
+                    }
+                  />
+                </label>
+                <label>
+                  Deskew{" "}
+                  <output>{selected.adjustments.deskew.toFixed(1)}°</output>
+                  <input
+                    aria-label="Deskew adjustment"
+                    type="range"
+                    min="-5"
+                    max="5"
+                    step="0.1"
+                    value={selected.adjustments.deskew}
+                    onChange={(event) =>
+                      patchSelected({ deskew: Number(event.target.value) })
+                    }
+                  />
+                </label>
+                <button type="button" onClick={() => void runDeskew()}>
+                  Detect deskew
+                </button>
+              </fieldset>
+              <div className="action-panel">
+                <section>
+                  <h3>Page image</h3>
+                  <p>
+                    Exports use a bounded 10-megapixel render; the preview uses
+                    1.2 megapixels.
+                  </p>
+                  <div className="button-row">
+                    <button
+                      type="button"
+                      disabled={busy}
+                      onClick={() => void exportCurrentImage("image/png")}
+                    >
+                      Download PNG
+                    </button>
+                    <button
+                      type="button"
+                      disabled={busy}
+                      onClick={() => void exportCurrentImage("image/jpeg")}
+                    >
+                      Download JPEG
+                    </button>
+                  </div>
+                </section>
+                <section>
+                  <h3>English OCR</h3>
+                  <p>
+                    The bundled model and WebAssembly runtime load only after
+                    confirmation. Expect roughly 100–300 MiB of transient
+                    memory; accuracy is not guaranteed.
+                  </p>
+                  <label className="consent">
+                    <input
+                      type="checkbox"
+                      checked={ocrConsent}
+                      onChange={(event) => setOcrConsent(event.target.checked)}
+                    />{" "}
+                    I understand the OCR memory cost.
+                  </label>
+                  <div className="button-row">
+                    <button
+                      type="button"
+                      disabled={busy || !ocrConsent}
+                      onClick={() => void runOcr()}
+                    >
+                      Recognize selected page
+                    </button>
+                    {busy && ocrProgress ? (
+                      <button
+                        type="button"
+                        onClick={() =>
+                          void cancelOcr().catch((reason: unknown) =>
+                            setError(
+                              reason instanceof Error
+                                ? reason.message
+                                : "OCR cancellation failed.",
+                            ),
+                          )
+                        }
+                      >
+                        Cancel OCR
+                      </button>
+                    ) : null}
+                  </div>
+                  {ocrProgress ? (
+                    <label>
+                      OCR progress{" "}
+                      <progress value={ocrProgress.progress} max="1" />{" "}
+                      {ocrProgress.status}
+                    </label>
+                  ) : null}
+                </section>
+              </div>
+              {selected.ocrText !== undefined ? (
+                <section className="ocr-result">
+                  <div className="section-heading">
+                    <h3>Recognized text</h3>
+                    <span>
+                      {selected.ocrConfidence?.toFixed(1)}% engine confidence
+                    </span>
+                  </div>
+                  <textarea
+                    aria-label="Recognized text"
+                    value={selected.ocrText}
+                    onChange={(event) =>
+                      setPages((current) =>
+                        current.map((page) =>
+                          page.id === selected.id
+                            ? { ...page, ocrText: event.target.value }
+                            : page,
+                        ),
+                      )
+                    }
+                  />
+                  <button
+                    type="button"
+                    onClick={() =>
+                      triggerBlobDownload(
+                        new Blob([selected.ocrText ?? ""], {
+                          type: "text/plain;charset=utf-8",
+                        }),
+                        `${selected.name.replace(/\.[^.]+$/u, "")}.txt`,
+                      )
+                    }
+                  >
+                    Download text
+                  </button>
+                </section>
+              ) : null}
+            </section>
+          ) : null}
+          <aside className="export-card">
+            <p className="eyebrow">Document export</p>
+            <h2>PDF assembly</h2>
+            <label>
+              Page size
+              <select
+                value={pdfSize}
+                onChange={(event) =>
+                  setPdfSize(event.target.value as PdfPageSize)
+                }
+              >
+                <option value="a4">A4</option>
+                <option value="letter">US Letter</option>
+                <option value="source">Source at 300 dpi</option>
+              </select>
+            </label>
+            <label>
+              Margin <output>{pdfMargin} pt</output>
+              <input
+                type="range"
+                min="0"
+                max="72"
+                value={pdfMargin}
+                onChange={(event) => setPdfMargin(Number(event.target.value))}
+              />
+            </label>
+            <button
+              className="primary"
+              type="button"
+              disabled={busy}
+              onClick={() => void exportPdf()}
+            >
+              Download {pages.length}-page PDF
+            </button>
+            <p className="microcopy">
+              The PDF is image-only in v0.1. OCR text downloads separately; no
+              invisible text layer is guessed without reliable word geometry.
+            </p>
+          </aside>
+        </div>
+      )}
+    </main>
+  );
+}

src/main.tsx

@@ -0,0 +1,18 @@
+import { StrictMode } from "react";
+import { createRoot } from "react-dom/client";
+import { App } from "./App";
+
+createRoot(document.getElementById("root")!).render(
+  <StrictMode>
+    <App />
+  </StrictMode>,
+);
+
+if ("serviceWorker" in navigator && import.meta.env.PROD) {
+  window.addEventListener("load", () => {
+    const url = new URL("./sw.js", document.baseURI);
+    void navigator.serviceWorker
+      .register(url, { scope: new URL("./", document.baseURI).pathname })
+      .catch(() => undefined);
+  });
+}

src/scan/export.ts

@@ -0,0 +1,93 @@
+import { triggerBlobDownload } from "@add-ideas/toolbox-helpers";
+import { canvasBlob, renderPage } from "./render";
+import { MAX_EXPORT_PIXELS, type ScanPage } from "./types";
+
+export type PdfPageSize = "source" | "a4" | "letter";
+
+export async function exportImage(
+  page: ScanPage,
+  type: "image/png" | "image/jpeg",
+) {
+  const rendered = await renderPage(page, MAX_EXPORT_PIXELS);
+  const blob = await canvasBlob(rendered.canvas, type);
+  const extension = type === "image/png" ? "png" : "jpg";
+  triggerBlobDownload(
+    blob,
+    `${page.name.replace(/\.[^.]+$/u, "")}-scan.${extension}`,
+  );
+}
+
+function pagePoints(
+  pageSize: PdfPageSize,
+  width: number,
+  height: number,
+): [number, number] {
+  if (pageSize === "a4") return [595.28, 841.89];
+  if (pageSize === "letter") return [612, 792];
+  return [(width / 300) * 72, (height / 300) * 72];
+}
+
+export async function buildPdf(
+  pages: ScanPage[],
+  pageSize: PdfPageSize,
+  marginPoints: number,
+  onProgress: (completed: number, total: number) => void,
+): Promise<Blob> {
+  if (pages.length === 0)
+    throw new RangeError("Add at least one page before exporting a PDF.");
+  const [{ jsPDF }, first] = await Promise.all([
+    import("jspdf"),
+    renderPage(pages[0]!, MAX_EXPORT_PIXELS),
+  ]);
+  const firstSize = pagePoints(
+    pageSize,
+    first.canvas.width,
+    first.canvas.height,
+  );
+  const pdf = new jsPDF({
+    unit: "pt",
+    format: firstSize,
+    orientation: firstSize[0] > firstSize[1] ? "landscape" : "portrait",
+    compress: true,
+    putOnlyUsedFonts: true,
+  });
+  for (let index = 0; index < pages.length; index += 1) {
+    const rendered =
+      index === 0 ? first : await renderPage(pages[index]!, MAX_EXPORT_PIXELS);
+    const dimensions = pagePoints(
+      pageSize,
+      rendered.canvas.width,
+      rendered.canvas.height,
+    );
+    if (index > 0)
+      pdf.addPage(
+        dimensions,
+        dimensions[0] > dimensions[1] ? "landscape" : "portrait",
+      );
+    const availableWidth = Math.max(1, dimensions[0] - marginPoints * 2);
+    const availableHeight = Math.max(1, dimensions[1] - marginPoints * 2);
+    const ratio = Math.min(
+      availableWidth / rendered.canvas.width,
+      availableHeight / rendered.canvas.height,
+    );
+    const width = rendered.canvas.width * ratio;
+    const height = rendered.canvas.height * ratio;
+    const left = (dimensions[0] - width) / 2;
+    const top = (dimensions[1] - height) / 2;
+    pdf.addImage(
+      rendered.canvas.toDataURL("image/jpeg", 0.9),
+      "JPEG",
+      left,
+      top,
+      width,
+      height,
+      undefined,
+      "FAST",
+    );
+    onProgress(index + 1, pages.length);
+    await new Promise<void>((resolve) =>
+      requestAnimationFrame(() => resolve()),
+    );
+  }
+  return pdf.output("blob");
+}

src/scan/geometry.ts

@@ -0,0 +1,129 @@
+import type { Point, Quad } from "./types";
+
+const EPSILON = 1e-8;
+
+export function clamp(value: number, minimum = 0, maximum = 1): number {
+  return Math.min(maximum, Math.max(minimum, value));
+}
+
+export function polygonArea(points: readonly Point[]): number {
+  let sum = 0;
+  for (let index = 0; index < points.length; index += 1) {
+    const current = points[index]!;
+    const next = points[(index + 1) % points.length]!;
+    sum += current.x * next.y - next.x * current.y;
+  }
+  return Math.abs(sum) / 2;
+}
+
+function cross(first: Point, second: Point, third: Point): number {
+  return (
+    (second.x - first.x) * (third.y - second.y) -
+    (second.y - first.y) * (third.x - second.x)
+  );
+}
+
+export function isValidQuad(quad: Quad): boolean {
+  if (
+    quad.some((point) => !Number.isFinite(point.x) || !Number.isFinite(point.y))
+  )
+    return false;
+  if (
+    quad.some(
+      (point) => point.x < 0 || point.x > 1 || point.y < 0 || point.y > 1,
+    )
+  )
+    return false;
+  if (polygonArea(quad) < 0.01) return false;
+  const signs = quad.map((_, index) =>
+    Math.sign(
+      cross(quad[index]!, quad[(index + 1) % 4]!, quad[(index + 2) % 4]!),
+    ),
+  );
+  return signs.every((sign) => sign !== 0 && sign === signs[0]);
+}
+
+export function moveQuadPoint(quad: Quad, index: number, point: Point): Quad {
+  const candidate = quad.map((item) => ({ ...item })) as Quad;
+  const current = candidate[index];
+  if (!current) return quad;
+  current.x = clamp(point.x);
+  current.y = clamp(point.y);
+  return isValidQuad(candidate) ? candidate : quad;
+}
+
+function distance(first: Point, second: Point, width: number, height: number) {
+  return Math.hypot(
+    (second.x - first.x) * width,
+    (second.y - first.y) * height,
+  );
+}
+
+export function correctedDimensions(
+  quad: Quad,
+  sourceWidth: number,
+  sourceHeight: number,
+  maximumPixels: number,
+): { width: number; height: number; scale: number } {
+  if (!isValidQuad(quad))
+    throw new RangeError(
+      "The document corners do not form a usable quadrilateral.",
+    );
+  const width = Math.max(
+    16,
+    Math.round(
+      (distance(quad[0], quad[1], sourceWidth, sourceHeight) +
+        distance(quad[3], quad[2], sourceWidth, sourceHeight)) /
+        2,
+    ),
+  );
+  const height = Math.max(
+    16,
+    Math.round(
+      (distance(quad[0], quad[3], sourceWidth, sourceHeight) +
+        distance(quad[1], quad[2], sourceWidth, sourceHeight)) /
+        2,
+    ),
+  );
+  const scale = Math.min(1, Math.sqrt(maximumPixels / (width * height)));
+  return {
+    width: Math.max(16, Math.floor(width * scale)),
+    height: Math.max(16, Math.floor(height * scale)),
+    scale,
+  };
+}
+
+/** Build the projective map from a unit square into the source quadrilateral. */
+export function squareToQuad(quad: Quad) {
+  const [p0, p1, p2, p3] = quad;
+  const dx1 = p1.x - p2.x;
+  const dx2 = p3.x - p2.x;
+  const dx3 = p0.x - p1.x + p2.x - p3.x;
+  const dy1 = p1.y - p2.y;
+  const dy2 = p3.y - p2.y;
+  const dy3 = p0.y - p1.y + p2.y - p3.y;
+  const denominator = dx1 * dy2 - dx2 * dy1;
+  let g = 0;
+  let h = 0;
+  if (Math.abs(dx3) > EPSILON || Math.abs(dy3) > EPSILON) {
+    if (Math.abs(denominator) < EPSILON)
+      throw new RangeError(
+        "The selected corners produce a degenerate perspective transform.",
+      );
+    g = (dx3 * dy2 - dx2 * dy3) / denominator;
+    h = (dx1 * dy3 - dx3 * dy1) / denominator;
+  }
+  const a = p1.x - p0.x + g * p1.x;
+  const b = p3.x - p0.x + h * p3.x;
+  const c = p0.x;
+  const d = p1.y - p0.y + g * p1.y;
+  const e = p3.y - p0.y + h * p3.y;
+  const f = p0.y;
+  return (x: number, y: number): Point => {
+    const divisor = g * x + h * y + 1;
+    return {
+      x: (a * x + b * y + c) / divisor,
+      y: (d * x + e * y + f) / divisor,
+    };
+  };
+}

src/scan/ocr.ts

@@ -0,0 +1,56 @@
+import type { Worker } from "tesseract.js";
+
+let activeWorker: Worker | undefined;
+let creation: Promise<Worker> | undefined;
+
+function localAsset(relative: string): string {
+  return new URL(relative, document.baseURI).href;
+}
+
+async function worker(onProgress: (status: string, progress: number) => void) {
+  if (activeWorker) return activeWorker;
+  if (!creation) {
+    creation = import("tesseract.js")
+      .then(({ createWorker, OEM }) =>
+        createWorker("eng", OEM.LSTM_ONLY, {
+          workerPath: localAsset("./ocr/worker.min.js"),
+          corePath: localAsset("./ocr/core"),
+          langPath: localAsset("./ocr/lang"),
+          cacheMethod: "none",
+          logger: (message) =>
+            onProgress(
+              String(message.status ?? "Working"),
+              typeof message.progress === "number" ? message.progress : 0,
+            ),
+        }),
+      )
+      .then((value) => {
+        activeWorker = value;
+        return value;
+      })
+      .finally(() => {
+        creation = undefined;
+      });
+  }
+  return creation;
+}
+
+export async function recognizeEnglish(
+  image: Blob,
+  onProgress: (status: string, progress: number) => void,
+): Promise<{ text: string; confidence: number }> {
+  const instance = await worker(onProgress);
+  const result = await instance.recognize(image);
+  return { text: result.data.text, confidence: result.data.confidence };
+}
+
+export async function cancelOcr(): Promise<void> {
+  const pending = activeWorker ?? (await creation?.catch(() => undefined));
+  activeWorker = undefined;
+  creation = undefined;
+  await pending?.terminate();
+}
+
+export async function closeOcr(): Promise<void> {
+  await cancelOcr();
+}

src/scan/pixels.ts

@@ -0,0 +1,138 @@
+export function luminance(red: number, green: number, blue: number): number {
+  return Math.round(red * 0.2126 + green * 0.7152 + blue * 0.0722);
+}
+
+export function otsuThreshold(data: Uint8ClampedArray): number {
+  const histogram = new Uint32Array(256);
+  let pixels = 0;
+  for (let index = 0; index + 3 < data.length; index += 4) {
+    if ((data[index + 3] ?? 0) === 0) continue;
+    const value = luminance(
+      data[index] ?? 0,
+      data[index + 1] ?? 0,
+      data[index + 2] ?? 0,
+    );
+    histogram[value] = (histogram[value] ?? 0) + 1;
+    pixels += 1;
+  }
+  if (pixels === 0) return 127;
+  let total = 0;
+  for (let value = 0; value < 256; value += 1)
+    total += value * (histogram[value] ?? 0);
+  let backgroundWeight = 0;
+  let backgroundTotal = 0;
+  let maximumVariance = -1;
+  let threshold = 127;
+  for (let value = 0; value < 256; value += 1) {
+    const count = histogram[value] ?? 0;
+    backgroundWeight += count;
+    if (backgroundWeight === 0) continue;
+    const foregroundWeight = pixels - backgroundWeight;
+    if (foregroundWeight === 0) break;
+    backgroundTotal += value * count;
+    const backgroundMean = backgroundTotal / backgroundWeight;
+    const foregroundMean = (total - backgroundTotal) / foregroundWeight;
+    const variance =
+      backgroundWeight *
+      foregroundWeight *
+      (backgroundMean - foregroundMean) ** 2;
+    if (variance > maximumVariance) {
+      maximumVariance = variance;
+      threshold = value;
+    }
+  }
+  return threshold;
+}
+
+export interface PixelAdjustments {
+  colourMode: "colour" | "grayscale" | "threshold";
+  threshold: number | "auto";
+  brightness: number;
+  contrast: number;
+}
+
+export function adjustPixels(
+  input: Uint8ClampedArray,
+  options: PixelAdjustments,
+): Uint8ClampedArray {
+  const output = new Uint8ClampedArray(input);
+  const factor =
+    (259 * (options.contrast + 255)) / (255 * (259 - options.contrast));
+  const threshold =
+    options.threshold === "auto" ? otsuThreshold(input) : options.threshold;
+  for (let index = 0; index + 3 < output.length; index += 4) {
+    const alpha = output[index + 3] ?? 0;
+    const values = [
+      output[index] ?? 0,
+      output[index + 1] ?? 0,
+      output[index + 2] ?? 0,
+    ].map((value) => factor * (value - 128) + 128 + options.brightness);
+    if (options.colourMode === "colour") {
+      output[index] = values[0]!;
+      output[index + 1] = values[1]!;
+      output[index + 2] = values[2]!;
+    } else {
+      const gray = luminance(values[0]!, values[1]!, values[2]!);
+      const value =
+        options.colourMode === "threshold"
+          ? gray <= threshold
+            ? 0
+            : 255
+          : gray;
+      output[index] = value;
+      output[index + 1] = value;
+      output[index + 2] = value;
+    }
+    output[index + 3] = alpha;
+  }
+  return output;
+}
+
+/** Estimate the correction angle by maximizing horizontal projection contrast. */
+export function estimateDeskew(
+  data: Uint8ClampedArray,
+  width: number,
+  height: number,
+): number {
+  if (width < 16 || height < 16 || data.length !== width * height * 4) return 0;
+  const threshold = otsuThreshold(data);
+  const centerX = (width - 1) / 2;
+  const centerY = (height - 1) / 2;
+  let bestAngle = 0;
+  let bestScore = -1;
+  for (let angle = -5; angle <= 5.001; angle += 0.5) {
+    const radians = (angle * Math.PI) / 180;
+    const sine = Math.sin(radians);
+    const cosine = Math.cos(radians);
+    const rows = new Uint32Array(height + Math.ceil(width * 0.1) + 4);
+    const offset = Math.floor((rows.length - height) / 2);
+    let dark = 0;
+    for (let y = 1; y < height - 1; y += 2) {
+      for (let x = 1; x < width - 1; x += 2) {
+        const index = (y * width + x) * 4;
+        if (
+          luminance(
+            data[index] ?? 255,
+            data[index + 1] ?? 255,
+            data[index + 2] ?? 255,
+          ) > threshold
+        )
+          continue;
+        const rotatedY =
+          Math.round((y - centerY) * cosine + (x - centerX) * sine + centerY) +
+          offset;
+        if (rotatedY >= 0 && rotatedY < rows.length)
+          rows[rotatedY] = (rows[rotatedY] ?? 0) + 1;
+        dark += 1;
+      }
+    }
+    if (dark < 12) return 0;
+    let score = 0;
+    for (const count of rows) score += count * count;
+    if (score > bestScore) {
+      bestScore = score;
+      bestAngle = angle;
+    }
+  }
+  return Math.abs(bestAngle) < 0.25 ? 0 : Math.round(bestAngle * 2) / 2;
+}

src/scan/render.ts

@@ -0,0 +1,249 @@
+import { correctedDimensions, squareToQuad } from "./geometry";
+import { adjustPixels, estimateDeskew } from "./pixels";
+import {
+  MAX_SOURCE_PIXELS,
+  type PageAdjustments,
+  type ScanPage,
+} from "./types";
+
+const MAX_WORKING_SOURCE_PIXELS = 24_000_000;
+
+function canvas(width: number, height: number): HTMLCanvasElement {
+  const element = document.createElement("canvas");
+  element.width = width;
+  element.height = height;
+  return element;
+}
+
+function context(element: HTMLCanvasElement) {
+  const value = element.getContext("2d", { willReadFrequently: true });
+  if (!value) throw new Error("This browser could not create a 2D canvas.");
+  return value;
+}
+
+export async function inspectImage(
+  file: File,
+): Promise<{ width: number; height: number }> {
+  const bitmap = await createImageBitmap(file);
+  try {
+    if (bitmap.width * bitmap.height > MAX_SOURCE_PIXELS)
+      throw new RangeError(
+        `Decoded image exceeds ${MAX_SOURCE_PIXELS.toLocaleString()} pixels.`,
+      );
+    return { width: bitmap.width, height: bitmap.height };
+  } finally {
+    bitmap.close();
+  }
+}
+
+function sampleBilinear(
+  data: Uint8ClampedArray,
+  width: number,
+  height: number,
+  x: number,
+  y: number,
+  channel: number,
+): number {
+  const clampedX = Math.max(0, Math.min(width - 1, x));
+  const clampedY = Math.max(0, Math.min(height - 1, y));
+  const x0 = Math.floor(clampedX);
+  const y0 = Math.floor(clampedY);
+  const x1 = Math.min(width - 1, x0 + 1);
+  const y1 = Math.min(height - 1, y0 + 1);
+  const fx = clampedX - x0;
+  const fy = clampedY - y0;
+  const top =
+    (data[(y0 * width + x0) * 4 + channel] ?? 0) * (1 - fx) +
+    (data[(y0 * width + x1) * 4 + channel] ?? 0) * fx;
+  const bottom =
+    (data[(y1 * width + x0) * 4 + channel] ?? 0) * (1 - fx) +
+    (data[(y1 * width + x1) * 4 + channel] ?? 0) * fx;
+  return top * (1 - fy) + bottom * fy;
+}
+
+function perspectiveCorrect(
+  source: ImageData,
+  outputWidth: number,
+  outputHeight: number,
+  adjustments: PageAdjustments,
+): ImageData {
+  const mapping = squareToQuad(adjustments.quad);
+  const output = new ImageData(outputWidth, outputHeight);
+  for (let y = 0; y < outputHeight; y += 1) {
+    const normalizedY = outputHeight === 1 ? 0 : y / (outputHeight - 1);
+    for (let x = 0; x < outputWidth; x += 1) {
+      const normalizedX = outputWidth === 1 ? 0 : x / (outputWidth - 1);
+      const sourcePoint = mapping(normalizedX, normalizedY);
+      const sourceX = sourcePoint.x * (source.width - 1);
+      const sourceY = sourcePoint.y * (source.height - 1);
+      const outputIndex = (y * outputWidth + x) * 4;
+      output.data[outputIndex] = sampleBilinear(
+        source.data,
+        source.width,
+        source.height,
+        sourceX,
+        sourceY,
+        0,
+      );
+      output.data[outputIndex + 1] = sampleBilinear(
+        source.data,
+        source.width,
+        source.height,
+        sourceX,
+        sourceY,
+        1,
+      );
+      output.data[outputIndex + 2] = sampleBilinear(
+        source.data,
+        source.width,
+        source.height,
+        sourceX,
+        sourceY,
+        2,
+      );
+      output.data[outputIndex + 3] = 255;
+    }
+  }
+  output.data.set(adjustPixels(output.data, adjustments));
+  return output;
+}
+
+function rotate(source: HTMLCanvasElement, degrees: number): HTMLCanvasElement {
+  const normalized = ((degrees % 360) + 360) % 360;
+  if (Math.abs(normalized) < 0.001) return source;
+  const radians = (normalized * Math.PI) / 180;
+  const width = Math.ceil(
+    Math.abs(source.width * Math.cos(radians)) +
+      Math.abs(source.height * Math.sin(radians)),
+  );
+  const height = Math.ceil(
+    Math.abs(source.width * Math.sin(radians)) +
+      Math.abs(source.height * Math.cos(radians)),
+  );
+  const output = canvas(width, height);
+  const outputContext = context(output);
+  outputContext.fillStyle = "white";
+  outputContext.fillRect(0, 0, width, height);
+  outputContext.translate(width / 2, height / 2);
+  outputContext.rotate(radians);
+  outputContext.drawImage(source, -source.width / 2, -source.height / 2);
+  return output;
+}
+
+function boundPixels(
+  source: HTMLCanvasElement,
+  maximumPixels: number,
+): HTMLCanvasElement {
+  if (source.width * source.height <= maximumPixels) return source;
+  const scale = Math.sqrt(maximumPixels / (source.width * source.height));
+  const output = canvas(
+    Math.max(16, Math.floor(source.width * scale)),
+    Math.max(16, Math.floor(source.height * scale)),
+  );
+  const outputContext = context(output);
+  outputContext.imageSmoothingEnabled = true;
+  outputContext.imageSmoothingQuality = "high";
+  outputContext.drawImage(source, 0, 0, output.width, output.height);
+  return output;
+}
+
+export interface RenderedPage {
+  canvas: HTMLCanvasElement;
+  sourceScale: number;
+  outputScale: number;
+}
+
+export async function renderPage(
+  page: ScanPage,
+  maximumPixels: number,
+): Promise<RenderedPage> {
+  const bitmap = await createImageBitmap(page.source);
+  try {
+    const sourceScale = Math.min(
+      1,
+      Math.sqrt(MAX_WORKING_SOURCE_PIXELS / (bitmap.width * bitmap.height)),
+    );
+    const sourceCanvas = canvas(
+      Math.max(1, Math.round(bitmap.width * sourceScale)),
+      Math.max(1, Math.round(bitmap.height * sourceScale)),
+    );
+    const sourceContext = context(sourceCanvas);
+    sourceContext.drawImage(
+      bitmap,
+      0,
+      0,
+      sourceCanvas.width,
+      sourceCanvas.height,
+    );
+    const dimensions = correctedDimensions(
+      page.adjustments.quad,
+      sourceCanvas.width,
+      sourceCanvas.height,
+      maximumPixels,
+    );
+    const corrected = canvas(dimensions.width, dimensions.height);
+    context(corrected).putImageData(
+      perspectiveCorrect(
+        sourceContext.getImageData(
+          0,
+          0,
+          sourceCanvas.width,
+          sourceCanvas.height,
+        ),
+        dimensions.width,
+        dimensions.height,
+        page.adjustments,
+      ),
+      0,
+      0,
+    );
+    const rotated = rotate(
+      corrected,
+      page.adjustments.quarterTurns * 90 + page.adjustments.deskew,
+    );
+    return {
+      canvas: boundPixels(rotated, maximumPixels),
+      sourceScale,
+      outputScale: dimensions.scale,
+    };
+  } finally {
+    bitmap.close();
+  }
+}
+
+export async function detectDeskew(page: ScanPage): Promise<number> {
+  const bitmap = await createImageBitmap(page.source);
+  try {
+    const scale = Math.min(1, 420 / Math.max(bitmap.width, bitmap.height));
+    const work = canvas(
+      Math.max(16, Math.round(bitmap.width * scale)),
+      Math.max(16, Math.round(bitmap.height * scale)),
+    );
+    const workContext = context(work);
+    workContext.drawImage(bitmap, 0, 0, work.width, work.height);
+    return estimateDeskew(
+      workContext.getImageData(0, 0, work.width, work.height).data,
+      work.width,
+      work.height,
+    );
+  } finally {
+    bitmap.close();
+  }
+}
+
+export function canvasBlob(
+  source: HTMLCanvasElement,
+  type: "image/png" | "image/jpeg",
+  quality = 0.92,
+): Promise<Blob> {
+  return new Promise((resolve, reject) => {
+    source.toBlob(
+      (blob) =>
+        blob
+          ? resolve(blob)
+          : reject(new Error("The browser could not encode the page.")),
+      type,
+      quality,
+    );
+  });
+}

src/scan/types.ts

@@ -0,0 +1,55 @@
+export const MAX_PAGE_BYTES = 32 * 1024 * 1024;
+export const MAX_SOURCE_PIXELS = 80_000_000;
+export const MAX_PAGES = 24;
+export const MAX_PREVIEW_PIXELS = 1_200_000;
+export const MAX_EXPORT_PIXELS = 10_000_000;
+
+export interface Point {
+  x: number;
+  y: number;
+}
+
+/** Top-left, top-right, bottom-right, bottom-left; coordinates are normalized. */
+export type Quad = [Point, Point, Point, Point];
+
+export type ColourMode = "colour" | "grayscale" | "threshold";
+
+export interface PageAdjustments {
+  quad: Quad;
+  quarterTurns: 0 | 1 | 2 | 3;
+  deskew: number;
+  colourMode: ColourMode;
+  threshold: number | "auto";
+  brightness: number;
+  contrast: number;
+}
+
+export interface ScanPage {
+  id: string;
+  name: string;
+  source: File;
+  width: number;
+  height: number;
+  adjustments: PageAdjustments;
+  ocrText?: string;
+  ocrConfidence?: number;
+}
+
+export const DEFAULT_QUAD: Quad = [
+  { x: 0, y: 0 },
+  { x: 1, y: 0 },
+  { x: 1, y: 1 },
+  { x: 0, y: 1 },
+];
+
+export function defaultAdjustments(): PageAdjustments {
+  return {
+    quad: DEFAULT_QUAD.map((point) => ({ ...point })) as Quad,
+    quarterTurns: 0,
+    deskew: 0,
+    colourMode: "colour",
+    threshold: "auto",
+    brightness: 0,
+    contrast: 0,
+  };
+}

src/styles.css

@@ -0,0 +1,491 @@
+:root {
+  color-scheme: light dark;
+  font-family:
+    Inter,
+    ui-sans-serif,
+    system-ui,
+    -apple-system,
+    BlinkMacSystemFont,
+    "Segoe UI",
+    sans-serif;
+  --scan-ink: var(--toolbox-text, #17212b);
+  --scan-muted: var(--toolbox-muted, #5f6b76);
+  --scan-panel: var(--toolbox-surface, #ffffff);
+  --scan-soft: color-mix(
+    in srgb,
+    var(--scan-panel) 91%,
+    var(--toolbox-accent, #296b66)
+  );
+  --scan-line: color-mix(in srgb, var(--scan-ink) 18%, transparent);
+  --scan-accent: var(--toolbox-accent, #176c63);
+  --scan-danger: #b3261e;
+}
+
+* {
+  box-sizing: border-box;
+}
+button,
+input,
+select,
+textarea {
+  font: inherit;
+}
+button,
+select,
+input[type="range"] {
+  min-height: 2.65rem;
+}
+button,
+select {
+  border: 1px solid var(--scan-line);
+  border-radius: 0.75rem;
+  background: var(--scan-panel);
+  color: var(--scan-ink);
+  padding: 0.6rem 0.85rem;
+}
+button {
+  cursor: pointer;
+  font-weight: 700;
+}
+button:hover:not(:disabled) {
+  border-color: var(--scan-accent);
+}
+button:focus-visible,
+input:focus-visible,
+select:focus-visible,
+textarea:focus-visible,
+[role="slider"]:focus-visible {
+  outline: 3px solid color-mix(in srgb, var(--scan-accent) 65%, transparent);
+  outline-offset: 2px;
+}
+button:disabled {
+  cursor: not-allowed;
+  opacity: 0.55;
+}
+
+.workbench {
+  width: min(100%, 90rem);
+  margin: 0 auto;
+  padding: 1rem;
+  color: var(--scan-ink);
+}
+.intro-card,
+.empty-card,
+.pages-card,
+.editor-card,
+.export-card,
+.preview-card,
+.action-panel > section,
+.ocr-result {
+  border: 1px solid var(--scan-line);
+  border-radius: 1rem;
+  background: var(--scan-panel);
+  box-shadow: 0 0.6rem 1.8rem color-mix(in srgb, #000 7%, transparent);
+}
+.intro-card {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1.5rem;
+  padding: 1.2rem 1.35rem;
+}
+.intro-card h2,
+.section-heading h2,
+.export-card h2,
+.empty-card h2 {
+  margin: 0.15rem 0 0.35rem;
+}
+.intro-card p:not(.eyebrow) {
+  max-width: 72ch;
+  margin: 0;
+  color: var(--scan-muted);
+}
+.eyebrow {
+  margin: 0;
+  color: var(--scan-accent);
+  text-transform: uppercase;
+  letter-spacing: 0.09em;
+  font-size: 0.73rem;
+  font-weight: 800;
+}
+.file-button {
+  flex: 0 0 auto;
+  display: inline-flex;
+  align-items: center;
+  min-height: 3rem;
+  border-radius: 0.8rem;
+  background: var(--scan-accent);
+  color: #fff;
+  padding: 0.7rem 1rem;
+  cursor: pointer;
+  font-weight: 800;
+}
+.file-button input {
+  position: absolute;
+  inline-size: 1px;
+  block-size: 1px;
+  opacity: 0;
+}
+.status-line {
+  min-height: 1.5rem;
+  margin: 0.75rem 0 0;
+  color: var(--scan-muted);
+}
+.error {
+  margin: 0.65rem 0;
+  border-left: 0.3rem solid var(--scan-danger);
+  border-radius: 0.4rem;
+  background: color-mix(in srgb, var(--scan-danger) 10%, var(--scan-panel));
+  padding: 0.7rem 0.9rem;
+}
+.empty-card {
+  margin-top: 1rem;
+  padding: 2rem;
+}
+.empty-card li + li {
+  margin-top: 0.45rem;
+}
+
+.workspace-grid {
+  display: grid;
+  grid-template-columns: 15.5rem minmax(0, 1fr) 15.5rem;
+  align-items: start;
+  gap: 1rem;
+  margin-top: 0.75rem;
+}
+.pages-card,
+.export-card {
+  position: sticky;
+  top: 5.3rem;
+  padding: 1rem;
+  max-height: calc(100vh - 6.5rem);
+  overflow: auto;
+}
+.editor-card {
+  min-width: 0;
+  padding: 1rem;
+}
+.section-heading {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 0.75rem;
+}
+.section-heading h3 {
+  margin: 0;
+}
+.section-heading small,
+.section-heading span {
+  color: var(--scan-muted);
+}
+.page-strip {
+  display: grid;
+  gap: 0.55rem;
+  list-style: none;
+  margin: 0.8rem 0;
+  padding: 0;
+}
+.page-strip li {
+  position: relative;
+  display: grid;
+  grid-template-columns: 1fr auto;
+  align-items: center;
+  border: 1px solid var(--scan-line);
+  border-radius: 0.8rem;
+  overflow: hidden;
+  background: var(--scan-soft);
+}
+.page-strip li.selected {
+  border-color: var(--scan-accent);
+  box-shadow: inset 0 0 0 1px var(--scan-accent);
+}
+.page-choice {
+  display: grid;
+  justify-items: start;
+  min-width: 0;
+  border: 0;
+  border-radius: 0;
+  background: transparent;
+  text-align: left;
+}
+.page-choice span,
+.page-choice small {
+  max-width: 11rem;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.page-choice small {
+  color: var(--scan-muted);
+}
+.drag-hint {
+  position: absolute;
+  right: 2.6rem;
+  color: var(--scan-muted);
+  cursor: grab;
+}
+.icon-button {
+  width: 2.45rem;
+  border: 0;
+  border-left: 1px solid var(--scan-line);
+  border-radius: 0;
+  background: transparent;
+  font-size: 1.3rem;
+}
+.microcopy {
+  margin: 0.35rem 0;
+  color: var(--scan-muted);
+  font-size: 0.84rem;
+  line-height: 1.45;
+}
+
+.preview-grid {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 0.8rem;
+  margin: 1rem 0;
+}
+.preview-card {
+  min-width: 0;
+  padding: 0.8rem;
+}
+.preview-card h3 {
+  margin: 0;
+  font-size: 1rem;
+}
+.source-stage,
+.processed-stage {
+  position: relative;
+  display: grid;
+  place-items: center;
+  width: 100%;
+  max-height: 28rem;
+  overflow: hidden;
+  border-radius: 0.6rem;
+  background-color: #3c4146;
+  background-image:
+    linear-gradient(45deg, #454b50 25%, transparent 25%),
+    linear-gradient(-45deg, #454b50 25%, transparent 25%),
+    linear-gradient(45deg, transparent 75%, #454b50 75%),
+    linear-gradient(-45deg, transparent 75%, #454b50 75%);
+  background-size: 20px 20px;
+  background-position:
+    0 0,
+    0 10px,
+    10px -10px,
+    -10px 0;
+}
+.source-stage img {
+  display: block;
+  width: 100%;
+  height: 100%;
+  object-fit: contain;
+}
+.source-stage svg {
+  position: absolute;
+  inset: 0;
+  width: 100%;
+  height: 100%;
+  touch-action: none;
+}
+.source-stage polygon {
+  fill: color-mix(in srgb, var(--scan-accent) 15%, transparent);
+  stroke: #6af8dc;
+  stroke-width: 0.65;
+  vector-effect: non-scaling-stroke;
+}
+.source-stage circle {
+  fill: #fff;
+  stroke: #08776b;
+  stroke-width: 0.8;
+  vector-effect: non-scaling-stroke;
+  cursor: move;
+}
+.source-stage text {
+  pointer-events: none;
+  fill: #092b28;
+  font-size: 3px;
+  font-weight: 900;
+  text-anchor: middle;
+  dominant-baseline: central;
+}
+.processed-stage {
+  min-height: 12rem;
+}
+.processed-stage canvas {
+  display: block;
+  max-width: 100%;
+  max-height: 28rem;
+  width: auto;
+  height: auto;
+}
+
+.controls-grid {
+  display: grid;
+  grid-template-columns: repeat(3, minmax(0, 1fr));
+  gap: 0.8rem;
+  border: 1px solid var(--scan-line);
+  border-radius: 0.9rem;
+  padding: 0.8rem;
+}
+.controls-grid legend {
+  padding: 0 0.35rem;
+  font-weight: 800;
+}
+.controls-grid label,
+.export-card label {
+  display: grid;
+  gap: 0.3rem;
+  font-weight: 700;
+  font-size: 0.9rem;
+}
+.controls-grid output,
+.export-card output {
+  justify-self: end;
+  color: var(--scan-muted);
+  font-variant-numeric: tabular-nums;
+}
+.action-panel {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 0.8rem;
+  margin-top: 0.8rem;
+}
+.action-panel > section,
+.ocr-result {
+  padding: 0.9rem;
+}
+.action-panel h3 {
+  margin: 0;
+}
+.action-panel p {
+  color: var(--scan-muted);
+}
+.button-row {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.45rem;
+}
+.consent {
+  display: flex;
+  gap: 0.5rem;
+  align-items: flex-start;
+  margin-bottom: 0.65rem;
+}
+.consent input {
+  margin-top: 0.2rem;
+}
+.ocr-result {
+  margin-top: 0.8rem;
+}
+.ocr-result textarea {
+  display: block;
+  width: 100%;
+  min-height: 12rem;
+  margin: 0.7rem 0;
+  resize: vertical;
+  border: 1px solid var(--scan-line);
+  border-radius: 0.7rem;
+  background: var(--scan-soft);
+  color: var(--scan-ink);
+  padding: 0.7rem;
+}
+.export-card {
+  display: grid;
+  gap: 0.8rem;
+}
+.export-card .primary {
+  background: var(--scan-accent);
+  color: #fff;
+}
+.loading {
+  width: min(100%, 90rem);
+  margin: 2rem auto;
+  padding: 1rem;
+}
+.help-dialog {
+  width: min(92vw, 42rem);
+  border: 1px solid var(--scan-line);
+  border-radius: 1rem;
+  background: var(--scan-panel);
+  color: var(--scan-ink);
+  padding: 1.2rem;
+}
+.help-dialog::backdrop {
+  background: rgb(0 0 0 / 0.52);
+}
+.dialog-heading {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 1rem;
+}
+.dialog-heading h2 {
+  margin: 0.2rem 0;
+}
+.dialog-heading button {
+  min-width: 2.65rem;
+  font-size: 1.3rem;
+}
+
+@media (max-width: 72rem) {
+  .workspace-grid {
+    grid-template-columns: 14rem minmax(0, 1fr);
+  }
+  .export-card {
+    position: static;
+    grid-column: 1 / -1;
+    max-height: none;
+    grid-template-columns: repeat(3, minmax(0, 1fr));
+    align-items: end;
+  }
+  .export-card > :is(.eyebrow, h2, .microcopy) {
+    grid-column: 1 / -1;
+  }
+}
+@media (max-width: 52rem) {
+  .intro-card {
+    align-items: stretch;
+    flex-direction: column;
+  }
+  .file-button {
+    justify-content: center;
+  }
+  .workspace-grid,
+  .preview-grid,
+  .action-panel {
+    grid-template-columns: 1fr;
+  }
+  .pages-card,
+  .export-card {
+    position: static;
+    max-height: none;
+  }
+  .controls-grid {
+    grid-template-columns: repeat(2, minmax(0, 1fr));
+  }
+}
+@media (max-width: 34rem) {
+  .workbench {
+    padding: 0.65rem;
+  }
+  .section-heading {
+    align-items: flex-start;
+    flex-direction: column;
+  }
+  .controls-grid,
+  .export-card {
+    grid-template-columns: 1fr;
+  }
+  .export-card > :is(.eyebrow, h2, .microcopy) {
+    grid-column: auto;
+  }
+}
+@media (prefers-reduced-motion: reduce) {
+  *,
+  *::before,
+  *::after {
+    scroll-behavior: auto !important;
+    transition: none !important;
+  }
+}

src/test/setup.ts

@@ -0,0 +1,8 @@
+import "@testing-library/jest-dom/vitest";
+import { afterEach } from "vitest";
+import { cleanup } from "@testing-library/react";
+
+afterEach(() => {
+  cleanup();
+  localStorage.clear();
+});

src/toolbox/manifest.source.json

@@ -0,0 +1,41 @@
+{
+  "$schema": "https://git.add-ideas.de/lotobo/toolbox-sdk/raw/branch/main/schemas/toolbox-app.v1.schema.json",
+  "schemaVersion": 1,
+  "id": "de.add-ideas.scan-tools",
+  "name": "Scan Tools",
+  "version": "0.1.0",
+  "description": "Correct, assemble, recognize and export scanned pages locally.",
+  "entry": "./",
+  "icon": "./favicon.svg",
+  "categories": ["document", "image", "productivity"],
+  "tags": ["scan", "camera", "deskew", "perspective", "ocr", "pdf"],
+  "integration": {
+    "contextVersion": 1,
+    "launchModes": ["navigate", "new-tab"],
+    "embedding": "unsupported"
+  },
+  "requirements": {
+    "secureContext": false,
+    "workers": true,
+    "indexedDb": false,
+    "crossOriginIsolated": false,
+    "topLevelContext": false
+  },
+  "privacy": {
+    "processing": "local",
+    "fileUploads": true,
+    "telemetry": false,
+    "label": "Page images, corrected pixels and OCR text stay in this browser; nothing is uploaded."
+  },
+  "source": {
+    "repository": "https://git.add-ideas.de/lotobo/scan-tools",
+    "license": "GPL-3.0-or-later"
+  },
+  "actions": [
+    {
+      "id": "source",
+      "label": "Source",
+      "url": "https://git.add-ideas.de/lotobo/scan-tools"
+    }
+  ]
+}

src/toolbox/manifest.ts

@@ -0,0 +1,4 @@
+import { defineToolboxApp, parseToolboxApp } from "@add-ideas/toolbox-contract";
+import source from "./manifest.source.json";
+
+export const manifest = defineToolboxApp(parseToolboxApp(source));

src/version.ts

@@ -0,0 +1 @@
+export const APP_VERSION = "0.1.0";

src/vite-env.d.ts

@@ -0,0 +1 @@
+/// <reference types="vite/client" />

tests/browser/app.spec.ts

@@ -0,0 +1,201 @@
+import { expect, test, type Page } from "@playwright/test";
+import { readFile } from "node:fs/promises";
+
+const ORIGIN = "http://127.0.0.1:4203";
+
+async function watchLocalOnly(page: Page) {
+  const external: string[] = [];
+  await page.route("**/*", async (route) => {
+    const url = new URL(route.request().url());
+    if (url.protocol.startsWith("http") && url.origin !== ORIGIN) {
+      external.push(url.href);
+      await route.abort();
+    } else await route.continue();
+  });
+  return external;
+}
+
+async function generatedPage(
+  page: Page,
+  name = "page.png",
+  text = "LOCAL SCAN",
+) {
+  const base64 = await page.evaluate((label) => {
+    const canvas = document.createElement("canvas");
+    canvas.width = 600;
+    canvas.height = 800;
+    const context = canvas.getContext("2d")!;
+    context.fillStyle = "white";
+    context.fillRect(0, 0, 600, 800);
+    context.strokeStyle = "#111";
+    context.lineWidth = 4;
+    context.strokeRect(35, 45, 530, 700);
+    context.fillStyle = "black";
+    context.font = "bold 52px sans-serif";
+    context.fillText(label, 95, 210);
+    context.font = "32px sans-serif";
+    context.fillText("Processed only in this browser", 65, 300);
+    return canvas.toDataURL("image/png").split(",")[1]!;
+  }, text);
+  return { name, mimeType: "image/png", buffer: Buffer.from(base64, "base64") };
+}
+
+test("loads the nested local-first empty workspace", async ({ page }) => {
+  await page.setViewportSize({ width: 1800, height: 1000 });
+  const external = await watchLocalOnly(page);
+  await page.goto("/deep/nested/scan-tools/");
+  await expect(page.getByRole("heading", { name: "Scan Tools" })).toBeVisible();
+  await expect(
+    page.getByRole("heading", { name: "No pages yet" }),
+  ).toBeVisible();
+  expect(external).toEqual([]);
+  expect(
+    await page
+      .locator(".toolbox-shell__main")
+      .evaluate((node) => getComputedStyle(node).width),
+  ).toBe("1440px");
+});
+
+test("adds and corrects a real local image while retaining the previous preview", async ({
+  page,
+}) => {
+  await page.goto("/deep/nested/scan-tools/");
+  await page
+    .getByLabel("Add images or camera pages")
+    .setInputFiles(await generatedPage(page));
+  await expect(page.getByRole("heading", { name: "page.png" })).toBeVisible();
+  const preview = page.getByLabel("Processed preview of page.png");
+  await expect
+    .poll(() => preview.evaluate((node: HTMLCanvasElement) => node.width))
+    .toBeGreaterThan(100);
+  const before = await preview.evaluate((node: HTMLCanvasElement) =>
+    node.toDataURL(),
+  );
+  await page.getByLabel("Brightness adjustment").fill("30");
+  await expect
+    .poll(() => preview.evaluate((node: HTMLCanvasElement) => node.toDataURL()))
+    .not.toBe(before);
+  await page
+    .getByRole("slider", { name: "Corner 1" })
+    .press("Shift+ArrowRight");
+  await expect(page.getByRole("slider", { name: "Corner 1" })).toHaveAttribute(
+    "aria-valuetext",
+    /^1% from left/u,
+  );
+  const download = page.waitForEvent("download");
+  await page.getByRole("button", { name: "Download PNG" }).click();
+  expect((await download).suggestedFilename()).toBe("page-scan.png");
+});
+
+test("assembles, reorders and removes pages", async ({ page }) => {
+  await page.goto("/deep/nested/scan-tools/");
+  await page
+    .getByLabel("Add images or camera pages")
+    .setInputFiles([
+      await generatedPage(page, "first.png", "FIRST"),
+      await generatedPage(page, "second.png", "SECOND"),
+    ]);
+  const cards = page.locator(".page-strip li");
+  await expect(cards).toHaveCount(2);
+  await cards.nth(0).dragTo(cards.nth(1));
+  await expect(cards.nth(0)).toContainText("second.png");
+  await page.getByRole("button", { name: "Remove page 1" }).click();
+  await expect(cards).toHaveCount(1);
+});
+
+test("exports a real image-only PDF", async ({ page }) => {
+  await page.goto("/deep/nested/scan-tools/");
+  await page
+    .getByLabel("Add images or camera pages")
+    .setInputFiles(await generatedPage(page));
+  const pending = page.waitForEvent("download");
+  await page.getByRole("button", { name: "Download 1-page PDF" }).click();
+  const download = await pending;
+  expect(download.suggestedFilename()).toBe("local-scan.pdf");
+  const path = await download.path();
+  expect(path).toBeTruthy();
+  expect((await readFile(path!)).subarray(0, 5).toString()).toBe("%PDF-");
+});
+
+test("serves the complete OCR runtime from the app origin", async ({
+  page,
+  request,
+}) => {
+  const external = await watchLocalOnly(page);
+  await page.goto("/deep/nested/scan-tools/");
+  for (const path of [
+    "ocr/worker.min.js",
+    "ocr/core/tesseract-core-lstm.wasm.js",
+    "ocr/core/tesseract-core-simd-lstm.wasm.js",
+    "ocr/core/tesseract-core-relaxedsimd-lstm.wasm.js",
+    "ocr/lang/eng.traineddata.gz",
+  ]) {
+    const response = await request.get(`/deep/nested/scan-tools/${path}`);
+    expect(response.ok(), path).toBe(true);
+    expect((await response.body()).byteLength, path).toBeGreaterThan(100_000);
+  }
+  expect(external).toEqual([]);
+});
+
+test("runs the bundled OCR engine without an external request", async ({
+  page,
+  browserName,
+}) => {
+  test.skip(
+    browserName !== "chromium",
+    "The engine path is exercised once; Firefox is covered by the asset, CSP, and UI matrix.",
+  );
+  const external = await watchLocalOnly(page);
+  await page.goto("/deep/nested/scan-tools/");
+  await page
+    .getByLabel("Add images or camera pages")
+    .setInputFiles(await generatedPage(page, "ocr.png", "LOCAL SCAN"));
+  await page.getByLabel("I understand the OCR memory cost.").check();
+  await page.getByRole("button", { name: "Recognize selected page" }).click();
+  await expect(page.getByLabel("Recognized text")).toBeVisible({
+    timeout: 90_000,
+  });
+  await expect(page.getByLabel("Recognized text")).toContainText(/LOCAL|SCAN/u);
+  expect(external).toEqual([]);
+});
+
+test("integrates help, themes, identity, headers and offline reload", async ({
+  page,
+  request,
+  context,
+}) => {
+  await page.goto("/deep/nested/scan-tools/");
+  await page.getByRole("button", { name: "Help" }).click();
+  await expect(
+    page.getByRole("dialog", { name: "About Scan Tools" }),
+  ).toContainText("image-only");
+  await page.keyboard.press("Escape");
+  await page.getByRole("button", { name: "Personalize" }).click();
+  await page.getByRole("button", { name: "Dark" }).click();
+  await expect(page.locator(".toolbox-shell").first()).toHaveAttribute(
+    "data-toolbox-theme",
+    "dark",
+  );
+  expect(
+    await page.evaluate(async () =>
+      Boolean(await navigator.serviceWorker.ready),
+    ),
+  ).toBe(true);
+  const index = await request.get("/deep/nested/scan-tools/");
+  expect(index.headers()["content-security-policy"]).toContain(
+    "worker-src 'self' blob:",
+  );
+  expect(await index.text()).not.toMatch(/\b(?:src|href)=["']\//u);
+  const manifest = await request.get(
+    "/deep/nested/scan-tools/toolbox-app.json",
+  );
+  await expect(manifest.json()).resolves.toMatchObject({
+    id: "de.add-ideas.scan-tools",
+    version: "0.1.0",
+    requirements: { workers: true },
+    privacy: { processing: "local", telemetry: false },
+  });
+  await context.setOffline(true);
+  await page.reload();
+  await expect(page.getByRole("heading", { name: "Scan Tools" })).toBeVisible();
+});

tests/components/app.test.tsx

@@ -0,0 +1,24 @@
+import { render, screen } from "@testing-library/react";
+import { describe, expect, it } from "vitest";
+import { Workbench } from "../../src/components/Workbench";
+
+describe("Scan Tools workbench", () => {
+  it("opens with a bounded local workflow and no content", () => {
+    render(<Workbench />);
+    expect(
+      screen.getByRole("heading", {
+        name: "Correct pages, assemble a document, then export.",
+      }),
+    ).toBeInTheDocument();
+    expect(
+      screen.getByRole("heading", { name: "No pages yet" }),
+    ).toBeInTheDocument();
+    expect(
+      screen.getByText(/Four-corner perspective correction/u),
+    ).toBeInTheDocument();
+    expect(screen.getByLabelText("Add images or camera pages")).toHaveAttribute(
+      "capture",
+      "environment",
+    );
+  });
+});

tests/scan/geometry.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from "vitest";
+import {
+  correctedDimensions,
+  isValidQuad,
+  moveQuadPoint,
+  polygonArea,
+  squareToQuad,
+} from "../../src/scan/geometry";
+import { DEFAULT_QUAD, type Quad } from "../../src/scan/types";
+
+describe("document geometry", () => {
+  it("validates ordered convex quadrilaterals", () => {
+    expect(isValidQuad(DEFAULT_QUAD)).toBe(true);
+    expect(polygonArea(DEFAULT_QUAD)).toBe(1);
+    expect(
+      isValidQuad([
+        { x: 0, y: 0 },
+        { x: 1, y: 1 },
+        { x: 1, y: 0 },
+        { x: 0, y: 1 },
+      ]),
+    ).toBe(false);
+  });
+
+  it("rejects a dragged corner that would invert the page", () => {
+    expect(moveQuadPoint(DEFAULT_QUAD, 0, { x: 0.9, y: 0.9 })).toEqual(
+      DEFAULT_QUAD,
+    );
+    expect(moveQuadPoint(DEFAULT_QUAD, 0, { x: 0.1, y: 0.1 })[0]).toEqual({
+      x: 0.1,
+      y: 0.1,
+    });
+  });
+
+  it("maps every destination corner onto the selected source corner", () => {
+    const quad: Quad = [
+      { x: 0.12, y: 0.08 },
+      { x: 0.9, y: 0.16 },
+      { x: 0.82, y: 0.94 },
+      { x: 0.05, y: 0.8 },
+    ];
+    const map = squareToQuad(quad);
+    expect(map(0, 0)).toEqual(quad[0]);
+    expect(map(1, 0).x).toBeCloseTo(quad[1].x);
+    expect(map(1, 1).y).toBeCloseTo(quad[2].y);
+    expect(map(0, 1).x).toBeCloseTo(quad[3].x);
+  });
+
+  it("preserves aspect and obeys the pixel budget", () => {
+    expect(correctedDimensions(DEFAULT_QUAD, 4000, 3000, 1_000_000)).toEqual({
+      width: 1154,
+      height: 866,
+      scale: expect.closeTo(Math.sqrt(1 / 12), 8),
+    });
+  });
+});

tests/scan/pixels.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, it } from "vitest";
+import {
+  adjustPixels,
+  estimateDeskew,
+  luminance,
+  otsuThreshold,
+} from "../../src/scan/pixels";
+
+function rgba(values: number[]) {
+  return new Uint8ClampedArray(
+    values.flatMap((value) => [value, value, value, 255]),
+  );
+}
+
+describe("document pixels", () => {
+  it("uses perceptual luminance", () => {
+    expect(luminance(255, 0, 0)).toBe(54);
+    expect(luminance(0, 255, 0)).toBe(182);
+    expect(luminance(0, 0, 255)).toBe(18);
+  });
+
+  it("finds a separating Otsu threshold", () => {
+    const threshold = otsuThreshold(rgba([5, 10, 15, 230, 240, 250]));
+    expect(threshold).toBeGreaterThanOrEqual(15);
+    expect(threshold).toBeLessThan(230);
+  });
+
+  it("creates an opaque black-and-white page", () => {
+    expect([
+      ...adjustPixels(rgba([20, 220]), {
+        colourMode: "threshold",
+        threshold: 100,
+        brightness: 0,
+        contrast: 0,
+      }),
+    ]).toEqual([0, 0, 0, 255, 255, 255, 255, 255]);
+  });
+
+  it("does not invent skew in an empty page", () => {
+    expect(estimateDeskew(rgba(new Array(20 * 20).fill(255)), 20, 20)).toBe(0);
+  });
+
+  it("returns the corrective angle for tilted text lines", () => {
+    const width = 120;
+    const height = 90;
+    const data = rgba(new Array(width * height).fill(255));
+    const slope = Math.tan((3 * Math.PI) / 180);
+    for (const baseline of [24, 44, 64]) {
+      for (let x = 8; x < width - 8; x += 1) {
+        const y = Math.round(baseline + (x - width / 2) * slope);
+        for (let thickness = -1; thickness <= 1; thickness += 1) {
+          const index = ((y + thickness) * width + x) * 4;
+          data[index] = 0;
+          data[index + 1] = 0;
+          data[index + 2] = 0;
+        }
+      }
+    }
+    expect(estimateDeskew(data, width, height)).toBeCloseTo(-3, 0);
+  });
+});

tsconfig.app.json

@@ -0,0 +1,27 @@
+{
+  "compilerOptions": {
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.app.tsbuildinfo",
+    "target": "ES2023",
+    "lib": ["ES2023", "DOM", "DOM.Iterable"],
+    "module": "ESNext",
+    "types": ["vite/client", "node"],
+    "allowArbitraryExtensions": true,
+    "skipLibCheck": true,
+    "moduleResolution": "Bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "moduleDetection": "force",
+    "noEmit": true,
+    "jsx": "react-jsx",
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "erasableSyntaxOnly": true,
+    "noFallthroughCasesInSwitch": true,
+    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "useDefineForClassFields": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true
+  },
+  "include": ["src", "tests"]
+}

tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "files": [],
+  "references": [
+    {
+      "path": "./tsconfig.app.json"
+    },
+    {
+      "path": "./tsconfig.node.json"
+    }
+  ]
+}

tsconfig.node.json

@@ -0,0 +1,24 @@
+{
+  "compilerOptions": {
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.node.tsbuildinfo",
+    "target": "ES2023",
+    "lib": ["ES2023"],
+    "module": "ESNext",
+    "types": ["node"],
+    "skipLibCheck": true,
+    "moduleResolution": "Bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "moduleDetection": "force",
+    "noEmit": true,
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true
+  },
+  "include": [
+    "vite.config.ts",
+    "playwright.config.ts",
+    "eslint.config.mjs",
+    "scripts/**/*.mjs"
+  ]
+}

vite.config.ts

@@ -0,0 +1,19 @@
+/// <reference types="vitest/config" />
+import { defineConfig } from "vite";
+import react from "@vitejs/plugin-react";
+
+export default defineConfig({
+  base: "./",
+  plugins: [react()],
+  test: {
+    environment: "jsdom",
+    setupFiles: "./src/test/setup.ts",
+    css: true,
+    pool: "threads",
+    maxWorkers: 1,
+    fileParallelism: false,
+    isolate: false,
+    restoreMocks: true,
+    exclude: ["tests/browser/**", "node_modules/**", "dist/**"],
+  },
+});