Release Scan Tools 0.2.0

.gitea/workflows/verify.yml

@@ -0,0 +1,39 @@
+name: Verify
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: verify-${{ gitea.repository }}-${{ gitea.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    env:
+      CI: "true"
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: npm
+      - name: Select declared npm version
+        run: npm install --global npm@11.17.0
+      - name: Install dependencies
+        run: npm ci
+      - name: Audit runtime dependencies
+        run: npm audit --omit=dev --audit-level=moderate
+      - name: Check, test, and build
+        run: npm run check
+      - name: Install browser engines
+        run: npx playwright install --with-deps chromium firefox webkit
+      - name: Browser tests
+        run: npm run test:browser

CHANGELOG.md

@@ -1,5 +1,14 @@
 # Changelog
 
+## 0.2.0 - 2026-09-02
+
+- Moved pixel and perspective processing into cancellable worker jobs with
+  progress, stale-result suppression and a bounded main-thread fallback.
+- Added precise manual corner fields, OCR word geometry overlays, hOCR/TSV
+  export and combined multipage text export.
+- Declared image/PDF/OCR input, export and optional worker/camera capability
+  profiles for Toolbox handoff.
+
 ## 0.1.0 - 2026-09-01
 
 - Add bounded multi-image and camera-picker ingestion with real decoded-pixel checks

README.md

@@ -4,23 +4,27 @@ 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
+## v0.2.0 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
+  support keyboard movement and precise percentage-coordinate entry
 - 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
+- Run perspective correction, pixel adjustment, rotation and deskew analysis in
+  cancellable OffscreenCanvas workers with progress; fall back to bounded main-
+  thread canvases only where those browser APIs are unavailable
 - 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
+  Tesseract.js WebAssembly runtime; inspect word geometry and export editable
+  text, hOCR, TSV, or combined multipage text
 - Work at nested paths, install as an offline PWA, use the shared system/light/
   dark themes, and perform no remote content request
 
@@ -28,7 +32,8 @@ Tools is a local-first module in the add·ideas Toolbox.
 
 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
+searchable invisible PDF text layer. Geometry is exported separately so an
+unverified alignment is never embedded into the PDF. 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.
 

SOURCE.md

@@ -1,7 +1,7 @@
 # Corresponding source
 
-The corresponding source for Scan Tools 0.1.0 is available at:
+The corresponding source for Scan Tools 0.2.0 is available at:
 
-https://git.add-ideas.de/lotobo/scan-tools/src/tag/v0.1.0
+https://git.add-ideas.de/lotobo/scan-tools/src/tag/v0.2.0
 
 Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.

THIRD_PARTY_NOTICES.md

@@ -1,12 +1,12 @@
 # Third-party notices
 
-Scan Tools 0.1.0 directly depends on these runtime packages:
+Scan Tools 0.2.0 directly depends on these runtime packages:
 
 | Package                          | Pinned version | Declared licence |
 | -------------------------------- | -------------: | ---------------- |
-| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-contract`    |          0.3.0 | Apache-2.0       |
-| `@add-ideas/toolbox-helpers`     |          0.1.0 | GPL-3.0-or-later |
+| `@add-ideas/toolbox-helpers`     |          0.2.0 | GPL-3.0-or-later |
-| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-shell-react` |          0.3.0 | Apache-2.0       |
 | `@tesseract.js-data/eng`         |          1.0.0 | MIT              |
 | `jspdf`                          |          4.2.1 | MIT              |
 | `react`                          |         19.2.8 | MIT              |

docs/ARCHITECTURE.md

@@ -5,13 +5,17 @@ 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
+The renderer uses a disposable module worker and `OffscreenCanvas` when the
-working ceiling. A projective map sends every destination pixel through the four
+browser supports them. It downscales exceptionally large source rasters to a
-selected source corners and samples it bilinearly. A bounded pixel pass applies
+24-megapixel working ceiling, then a projective map sends every destination
-brightness, contrast, perceptual grayscale and optional Otsu/manual threshold.
+pixel through the four selected source corners and samples it bilinearly. A
-Canvas rotation handles quarter turns and the final ±5 degree deskew. Preview,
+bounded pixel pass applies brightness, contrast, perceptual grayscale and
-OCR and export call the same renderer with different disclosed pixel budgets, so
+optional Otsu/manual threshold. Canvas rotation handles quarter turns and the
-the preview semantics match the downloaded result.
+final ±5 degree deskew. Worker jobs report stages, are terminated by abort and
+cannot replace a newer preview. A bounded HTML-canvas fallback preserves the
+same result where Worker/OffscreenCanvas are unavailable. Preview, OCR and
+export call this 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
@@ -24,3 +28,10 @@ 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.
+
+OCR requests bounded block geometry, hOCR and TSV alongside plain text. Word
+boxes are normalized to the corrected OCR raster for an inert SVG overlay and
+are capped at 100,000 entries. hOCR is never injected into the application DOM;
+it and TSV are download-only evidence. Any subsequent page adjustment clears
+positioned OCR artifacts while retaining the user's editable plain text. PDFs
+remain image-only rather than silently embedding a potentially misaligned layer.

package-lock.json

@@ -1,17 +1,17 @@
 {
   "name": "scan-tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "scan-tools",
-      "version": "0.1.0",
+      "version": "0.2.0",
       "license": "GPL-3.0-or-later",
       "dependencies": {
-        "@add-ideas/toolbox-contract": "0.2.3",
+        "@add-ideas/toolbox-contract": "0.3.0",
-        "@add-ideas/toolbox-helpers": "0.1.0",
+        "@add-ideas/toolbox-helpers": "0.2.0",
-        "@add-ideas/toolbox-shell-react": "0.2.3",
+        "@add-ideas/toolbox-shell-react": "0.3.0",
         "@tesseract.js-data/eng": "1.0.0",
         "jspdf": "4.2.1",
         "react": "19.2.8",
@@ -19,7 +19,7 @@
         "tesseract.js": "7.0.0"
       },
       "devDependencies": {
-        "@add-ideas/toolbox-testkit": "0.2.3",
+        "@add-ideas/toolbox-testkit": "0.3.0",
         "@eslint/js": "10.0.1",
         "@playwright/test": "1.62.1",
         "@testing-library/jest-dom": "6.9.1",
@@ -45,24 +45,24 @@
       }
     },
     "node_modules/@add-ideas/toolbox-contract": {
-      "version": "0.2.3",
+      "version": "0.3.0",
-      "license": "Apache-2.0",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-contract/-/0.3.0/toolbox-contract-0.3.0.tgz",
-      "engines": {
+      "integrity": "sha512-dKrK7BjOFwqJaBfJuhKxZKIld4sH0AKjEn6a0yLnbdMUFY+fFv4VSLGV2tNSBD016gumc2iNqOjUj/ld7x4rtA==",
-        "node": ">=20"
+      "license": "Apache-2.0"
-      }
     },
     "node_modules/@add-ideas/toolbox-helpers": {
-      "version": "0.1.0",
+      "version": "0.2.0",
-      "license": "GPL-3.0-or-later",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-helpers/-/0.2.0/toolbox-helpers-0.2.0.tgz",
-      "engines": {
+      "integrity": "sha512-SdOqkw+P+3J3fa5iVkzb5P15rVepB001GNV21Oh8w0CZcVL+YRltgD/s+MVcTyrNijWQf3E5vtQON/3N2LLyKg==",
-        "node": ">=22"
+      "license": "GPL-3.0-or-later"
-      }
     },
     "node_modules/@add-ideas/toolbox-shell-react": {
-      "version": "0.2.3",
+      "version": "0.3.0",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-shell-react/-/0.3.0/toolbox-shell-react-0.3.0.tgz",
+      "integrity": "sha512-74p6JzAOG0YCAKdlc1hLofV4ZIko7vb448S75cIiM88PKm93EHl5VD7g8YVyfM56Ui97UY9dmy+Whiq4sGzpsg==",
       "license": "Apache-2.0",
       "dependencies": {
-        "@add-ideas/toolbox-contract": "0.2.3"
+        "@add-ideas/toolbox-contract": "0.3.0"
       },
       "peerDependencies": {
         "react": ">=18 <20",
@@ -70,17 +70,16 @@
       }
     },
     "node_modules/@add-ideas/toolbox-testkit": {
-      "version": "0.2.3",
+      "version": "0.3.0",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-testkit/-/0.3.0/toolbox-testkit-0.3.0.tgz",
+      "integrity": "sha512-4Fk+oSvZFspOMIXr8Xy040nhAaBsIQAzsGyXWSpjn3+k3yBKq7nB1r5zCHhsXzfdLzvPDAx2KcmSNOhM330D9w==",
       "dev": true,
       "license": "Apache-2.0",
       "dependencies": {
-        "@add-ideas/toolbox-contract": "0.2.3"
+        "@add-ideas/toolbox-contract": "0.3.0"
       },
       "bin": {
         "toolbox-check": "dist/cli.js"
-      },
-      "engines": {
-        "node": ">=20"
       }
     },
     "node_modules/@adobe/css-tools": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "scan-tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Correct, assemble, recognize and export scanned pages locally in the browser.",
   "license": "GPL-3.0-or-later",
   "author": "Albrecht Degering",
@@ -40,9 +40,9 @@
     "ocr:prepare": "node scripts/prepare-ocr-assets.mjs"
   },
   "dependencies": {
-    "@add-ideas/toolbox-contract": "0.2.3",
+    "@add-ideas/toolbox-contract": "0.3.0",
-    "@add-ideas/toolbox-helpers": "0.1.0",
+    "@add-ideas/toolbox-helpers": "0.2.0",
-    "@add-ideas/toolbox-shell-react": "0.2.3",
+    "@add-ideas/toolbox-shell-react": "0.3.0",
     "@tesseract.js-data/eng": "1.0.0",
     "jspdf": "4.2.1",
     "react": "19.2.8",
@@ -50,7 +50,7 @@
     "tesseract.js": "7.0.0"
   },
   "devDependencies": {
-    "@add-ideas/toolbox-testkit": "0.2.3",
+    "@add-ideas/toolbox-testkit": "0.3.0",
     "@eslint/js": "10.0.1",
     "@playwright/test": "1.62.1",
     "@testing-library/jest-dom": "6.9.1",

playwright.config.ts

@@ -15,7 +15,25 @@ export default defineConfig({
     timeout: 180_000,
   },
   projects: [
-    { name: "chromium", use: { ...devices["Desktop Chrome"] } },
+    {
-    { name: "firefox", use: { ...devices["Desktop Firefox"] } },
+      name: "chromium",
+      testIgnore: /responsive\.spec\.ts/,
+      use: { ...devices["Desktop Chrome"] },
+    },
+    {
+      name: "firefox",
+      testIgnore: /responsive\.spec\.ts/,
+      use: { ...devices["Desktop Firefox"] },
+    },
+    {
+      name: "webkit",
+      testIgnore: /responsive\.spec\.ts/,
+      use: { ...devices["Desktop Safari"] },
+    },
+    {
+      name: "mobile-chromium",
+      testMatch: /responsive\.spec\.ts/,
+      use: { ...devices["Pixel 5"] },
+    },
   ],
 });

public/CHANGELOG.md

@@ -1,5 +1,14 @@
 # Changelog
 
+## 0.2.0 - 2026-09-02
+
+- Moved pixel and perspective processing into cancellable worker jobs with
+  progress, stale-result suppression and a bounded main-thread fallback.
+- Added precise manual corner fields, OCR word geometry overlays, hOCR/TSV
+  export and combined multipage text export.
+- Declared image/PDF/OCR input, export and optional worker/camera capability
+  profiles for Toolbox handoff.
+
 ## 0.1.0 - 2026-09-01
 
 - Add bounded multi-image and camera-picker ingestion with real decoded-pixel checks

public/LICENSES/npm-runtime-licenses.txt

@@ -1,5 +1,5 @@
 ==============================================================================
-@add-ideas/toolbox-contract@0.2.3
+@add-ideas/toolbox-contract@0.3.0
 Declared licence: Apache-2.0
 ==============================================================================
 --- LICENSE ---
@@ -198,7 +198,7 @@ Declared licence: Apache-2.0
 
 
 ==============================================================================
-@add-ideas/toolbox-helpers@0.1.0
+@add-ideas/toolbox-helpers@0.2.0
 Declared licence: GPL-3.0-or-later
 ==============================================================================
 --- LICENSE ---
@@ -879,7 +879,7 @@ Public License instead of this License.  But first, please read
 
 
 ==============================================================================
-@add-ideas/toolbox-shell-react@0.2.3
+@add-ideas/toolbox-shell-react@0.3.0
 Declared licence: Apache-2.0
 ==============================================================================
 --- LICENSE ---

public/README.md

@@ -4,23 +4,27 @@ 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
+## v0.2.0 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
+  support keyboard movement and precise percentage-coordinate entry
 - 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
+- Run perspective correction, pixel adjustment, rotation and deskew analysis in
+  cancellable OffscreenCanvas workers with progress; fall back to bounded main-
+  thread canvases only where those browser APIs are unavailable
 - 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
+  Tesseract.js WebAssembly runtime; inspect word geometry and export editable
+  text, hOCR, TSV, or combined multipage text
 - Work at nested paths, install as an offline PWA, use the shared system/light/
   dark themes, and perform no remote content request
 
@@ -28,7 +32,8 @@ Tools is a local-first module in the add·ideas Toolbox.
 
 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
+searchable invisible PDF text layer. Geometry is exported separately so an
+unverified alignment is never embedded into the PDF. 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.
 

public/SOURCE.md

@@ -1,7 +1,7 @@
 # Corresponding source
 
-The corresponding source for Scan Tools 0.1.0 is available at:
+The corresponding source for Scan Tools 0.2.0 is available at:
 
-https://git.add-ideas.de/lotobo/scan-tools/src/tag/v0.1.0
+https://git.add-ideas.de/lotobo/scan-tools/src/tag/v0.2.0
 
 Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.

public/THIRD_PARTY_NOTICES.md

@@ -1,12 +1,12 @@
 # Third-party notices
 
-Scan Tools 0.1.0 directly depends on these runtime packages:
+Scan Tools 0.2.0 directly depends on these runtime packages:
 
 | Package                          | Pinned version | Declared licence |
 | -------------------------------- | -------------: | ---------------- |
-| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-contract`    |          0.3.0 | Apache-2.0       |
-| `@add-ideas/toolbox-helpers`     |          0.1.0 | GPL-3.0-or-later |
+| `@add-ideas/toolbox-helpers`     |          0.2.0 | GPL-3.0-or-later |
-| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-shell-react` |          0.3.0 | Apache-2.0       |
 | `@tesseract.js-data/eng`         |          1.0.0 | MIT              |
 | `jspdf`                          |          4.2.1 | MIT              |
 | `react`                          |         19.2.8 | MIT              |

public/docs/ARCHITECTURE.md

@@ -5,13 +5,17 @@ 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
+The renderer uses a disposable module worker and `OffscreenCanvas` when the
-working ceiling. A projective map sends every destination pixel through the four
+browser supports them. It downscales exceptionally large source rasters to a
-selected source corners and samples it bilinearly. A bounded pixel pass applies
+24-megapixel working ceiling, then a projective map sends every destination
-brightness, contrast, perceptual grayscale and optional Otsu/manual threshold.
+pixel through the four selected source corners and samples it bilinearly. A
-Canvas rotation handles quarter turns and the final ±5 degree deskew. Preview,
+bounded pixel pass applies brightness, contrast, perceptual grayscale and
-OCR and export call the same renderer with different disclosed pixel budgets, so
+optional Otsu/manual threshold. Canvas rotation handles quarter turns and the
-the preview semantics match the downloaded result.
+final ±5 degree deskew. Worker jobs report stages, are terminated by abort and
+cannot replace a newer preview. A bounded HTML-canvas fallback preserves the
+same result where Worker/OffscreenCanvas are unavailable. Preview, OCR and
+export call this 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
@@ -24,3 +28,10 @@ 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.
+
+OCR requests bounded block geometry, hOCR and TSV alongside plain text. Word
+boxes are normalized to the corrected OCR raster for an inert SVG overlay and
+are capped at 100,000 entries. hOCR is never injected into the application DOM;
+it and TSV are download-only evidence. Any subsequent page adjustment clears
+positioned OCR artifacts while retaining the user's editable plain text. PDFs
+remain image-only rather than silently embedding a potentially misaligned layer.

public/sw.js

@@ -1,5 +1,5 @@
 const CACHE_PREFIX = "scan-tools-shell-";
-const CACHE_NAME = CACHE_PREFIX + "0.1.0";
+const CACHE_NAME = CACHE_PREFIX + "0.2.0";
 const CORE = ["./", "./manifest.webmanifest", "./favicon.svg"];
 self.addEventListener("install", (event) => {
   event.waitUntil(

public/toolbox-app.json

@@ -3,12 +3,12 @@
   "schemaVersion": 1,
   "id": "de.add-ideas.scan-tools",
   "name": "Scan Tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Correct, assemble, recognize and export scanned pages locally.",
   "entry": "./",
   "icon": "./favicon.svg",
   "categories": ["document", "image", "productivity"],
-  "tags": ["scan", "camera", "deskew", "perspective", "ocr", "pdf"],
+  "tags": ["scan", "camera", "deskew", "perspective", "ocr", "hocr", "pdf"],
   "integration": {
     "contextVersion": 1,
     "launchModes": ["navigate", "new-tab"],
@@ -16,11 +16,30 @@
   },
   "requirements": {
     "secureContext": false,
-    "workers": true,
+    "workers": false,
     "indexedDb": false,
     "crossOriginIsolated": false,
     "topLevelContext": false
   },
+  "io": {
+    "accepts": [
+      { "mediaType": "image/png", "extensions": [".png"] },
+      { "mediaType": "image/jpeg", "extensions": [".jpg", ".jpeg"] },
+      { "mediaType": "image/webp", "extensions": [".webp"] }
+    ],
+    "produces": [
+      { "mediaType": "image/png", "extensions": [".png"] },
+      { "mediaType": "image/jpeg", "extensions": [".jpg"] },
+      { "mediaType": "application/pdf", "extensions": [".pdf"] },
+      { "mediaType": "text/plain", "extensions": [".txt"] },
+      { "mediaType": "text/html", "extensions": [".hocr.html"] },
+      { "mediaType": "text/tab-separated-values", "extensions": [".tsv"] }
+    ]
+  },
+  "capabilities": {
+    "required": [],
+    "optional": ["workers", "offscreen-canvas", "webassembly", "camera-capture"]
+  },
   "privacy": {
     "processing": "local",
     "fileUploads": true,

src/components/Workbench.tsx

@@ -149,6 +149,55 @@ function SourceCorners({
           ))}
         </svg>
       </div>
+      <div className="corner-fields" aria-label="Precise corner coordinates">
+        {page.adjustments.quad.map((point, index) => (
+          <fieldset key={index}>
+            <legend>Corner {index + 1}</legend>
+            <label>
+              X (%)
+              <input
+                type="number"
+                min="0"
+                max="100"
+                step="0.1"
+                aria-label={`Corner ${index + 1} X (%)`}
+                value={Number((point.x * 100).toFixed(2))}
+                onChange={(event) => {
+                  if (!Number.isFinite(event.target.valueAsNumber)) return;
+                  update({
+                    ...page.adjustments,
+                    quad: moveQuadPoint(page.adjustments.quad, index, {
+                      x: event.target.valueAsNumber / 100,
+                      y: point.y,
+                    }),
+                  });
+                }}
+              />
+            </label>
+            <label>
+              Y (%)
+              <input
+                type="number"
+                min="0"
+                max="100"
+                step="0.1"
+                aria-label={`Corner ${index + 1} Y (%)`}
+                value={Number((point.y * 100).toFixed(2))}
+                onChange={(event) => {
+                  if (!Number.isFinite(event.target.valueAsNumber)) return;
+                  update({
+                    ...page.adjustments,
+                    quad: moveQuadPoint(page.adjustments.quad, index, {
+                      x: point.x,
+                      y: event.target.valueAsNumber / 100,
+                    }),
+                  });
+                }}
+              />
+            </label>
+          </fieldset>
+        ))}
+      </div>
     </section>
   );
 }
@@ -158,8 +207,14 @@ function ProcessedPreview({ page }: { page: ScanPage }) {
   const [state, setState] = useState("Rendering preview…");
   useEffect(() => {
     let current = true;
+    const controller = new AbortController();
     const timeout = window.setTimeout(() => {
-      void renderPage(page, MAX_PREVIEW_PIXELS)
+      void renderPage(page, MAX_PREVIEW_PIXELS, {
+        signal: controller.signal,
+        onProgress: (progress, stage) => {
+          if (current) setState(`${stage} · ${Math.round(progress * 100)}%`);
+        },
+      })
         .then((rendered) => {
           if (!current || !canvasRef.current) return;
           const target = canvasRef.current;
@@ -171,7 +226,10 @@ function ProcessedPreview({ page }: { page: ScanPage }) {
           );
         })
         .catch((reason: unknown) => {
-          if (current)
+          if (
+            current &&
+            !(reason instanceof DOMException && reason.name === "AbortError")
+          )
             setState(
               reason instanceof Error ? reason.message : "Preview failed.",
             );
@@ -179,6 +237,7 @@ function ProcessedPreview({ page }: { page: ScanPage }) {
     }, 120);
     return () => {
       current = false;
+      controller.abort();
       window.clearTimeout(timeout);
     };
   }, [page]);
@@ -189,10 +248,34 @@ function ProcessedPreview({ page }: { page: ScanPage }) {
         {state}
       </p>
       <div className="processed-stage">
-        <canvas
+        <div className="processed-image">
-          ref={canvasRef}
+          <canvas
-          aria-label={`Processed preview of ${page.name}`}
+            ref={canvasRef}
-        />
+            aria-label={`Processed preview of ${page.name}`}
+          />
+          {page.ocrWords?.length ? (
+            <svg
+              className="ocr-overlay"
+              viewBox="0 0 100 100"
+              preserveAspectRatio="none"
+              aria-label={`${page.ocrWords.length} positioned OCR words`}
+            >
+              {page.ocrWords.slice(0, 2_000).map((word, index) => (
+                <rect
+                  key={`${index}-${word.text}`}
+                  x={word.bbox.x0 * 100}
+                  y={word.bbox.y0 * 100}
+                  width={(word.bbox.x1 - word.bbox.x0) * 100}
+                  height={(word.bbox.y1 - word.bbox.y0) * 100}
+                >
+                  <title>
+                    {word.text} · {word.confidence.toFixed(1)}%
+                  </title>
+                </rect>
+              ))}
+            </svg>
+          ) : null}
+        </div>
       </div>
     </section>
   );
@@ -263,6 +346,10 @@ export function Workbench() {
     "Add photographs or image files to begin.",
   );
   const [busy, setBusy] = useState(false);
+  const [pixelProgress, setPixelProgress] = useState<{
+    value: number;
+    stage: string;
+  }>();
   const [ocrConsent, setOcrConsent] = useState(false);
   const [ocrProgress, setOcrProgress] = useState<{
     status: string;
@@ -270,10 +357,12 @@ export function Workbench() {
   }>();
   const [pdfSize, setPdfSize] = useState<PdfPageSize>("a4");
   const [pdfMargin, setPdfMargin] = useState(18);
+  const processing = useRef<AbortController | undefined>(undefined);
   const selected = pages.find((page) => page.id === selectedId) ?? pages[0];
 
   useEffect(
     () => () => {
+      processing.current?.abort();
       void closeOcr().catch(() => undefined);
     },
     [],
@@ -283,6 +372,38 @@ export function Workbench() {
     [pages],
   );
 
+  const beginProcessing = (stage: string) => {
+    processing.current?.abort();
+    const controller = new AbortController();
+    processing.current = controller;
+    setBusy(true);
+    setPixelProgress({ value: 0, stage });
+    return controller;
+  };
+
+  const reportProcessing = (value: number, stage: string) => {
+    setPixelProgress({ value, stage });
+  };
+
+  const finishProcessing = (controller: AbortController) => {
+    if (processing.current !== controller) return;
+    processing.current = undefined;
+    setBusy(false);
+    setPixelProgress(undefined);
+  };
+
+  const cancelProcessing = () => {
+    processing.current?.abort();
+    void cancelOcr().catch(() => undefined);
+    processing.current = undefined;
+    setBusy(false);
+    setPixelProgress(undefined);
+    setOcrProgress(undefined);
+    setNotice(
+      "Page processing cancelled; pages and prior output were retained.",
+    );
+  };
+
   const addFiles = async (event: ChangeEvent<HTMLInputElement>) => {
     const files = [...(event.target.files ?? [])];
     event.target.value = "";
@@ -343,7 +464,15 @@ export function Workbench() {
     if (!selected) return;
     setPages((current) =>
       current.map((page) =>
-        page.id === selected.id ? { ...page, adjustments } : page,
+        page.id === selected.id
+          ? {
+              ...page,
+              adjustments,
+              ocrWords: undefined,
+              ocrHocr: undefined,
+              ocrTsv: undefined,
+            }
+          : page,
       ),
     );
   };
@@ -353,11 +482,14 @@ export function Workbench() {
 
   const runDeskew = async () => {
     if (!selected) return;
-    setBusy(true);
+    const controller = beginProcessing("Preparing deskew detection");
     setError(undefined);
     setNotice("Estimating text-line angle locally…");
     try {
-      const angle = await detectDeskew(selected);
+      const angle = await detectDeskew(selected, {
+        signal: controller.signal,
+        onProgress: reportProcessing,
+      });
       patchSelected({ deskew: angle });
       setNotice(
         angle === 0
@@ -365,44 +497,70 @@ export function Workbench() {
           : `Applied an estimated ${angle.toFixed(1)}° correction.`,
       );
     } catch (reason) {
-      setError(
+      if (
-        reason instanceof Error ? reason.message : "Deskew estimation failed.",
+        !controller.signal.aborted &&
-      );
+        !(reason instanceof DOMException && reason.name === "AbortError")
+      )
+        setError(
+          reason instanceof Error
+            ? reason.message
+            : "Deskew estimation failed.",
+        );
     } finally {
-      setBusy(false);
+      finishProcessing(controller);
     }
   };
 
   const exportCurrentImage = async (type: "image/png" | "image/jpeg") => {
     if (!selected) return;
-    setBusy(true);
+    const controller = beginProcessing("Preparing image export");
     setError(undefined);
     setNotice(`Rendering ${type === "image/png" ? "PNG" : "JPEG"} locally…`);
     try {
-      await exportImage(selected, type);
+      await exportImage(selected, type, {
+        signal: controller.signal,
+        onProgress: reportProcessing,
+      });
       setNotice(
         `Rendered ${selected.name} within the 10-megapixel export budget.`,
       );
     } catch (reason) {
-      setError(
+      if (
-        `${reason instanceof Error ? reason.message : "Image export failed."} The workspace was retained.`,
+        !controller.signal.aborted &&
-      );
+        !(reason instanceof DOMException && reason.name === "AbortError")
+      )
+        setError(
+          `${reason instanceof Error ? reason.message : "Image export failed."} The workspace was retained.`,
+        );
     } finally {
-      setBusy(false);
+      finishProcessing(controller);
     }
   };
 
   const runOcr = async () => {
     if (!selected || !ocrConsent) return;
-    setBusy(true);
+    const controller = beginProcessing("Preparing OCR image");
     setError(undefined);
     setOcrProgress({ status: "Preparing local OCR", progress: 0 });
     try {
-      const rendered = await renderPage(selected, 4_000_000);
+      const rendered = await renderPage(selected, 4_000_000, {
+        signal: controller.signal,
+        onProgress: reportProcessing,
+      });
       const image = await canvasBlob(rendered.canvas, "image/png");
       const result = await recognizeEnglish(image, (status, progress) =>
         setOcrProgress({ status, progress }),
       );
+      const ocrWords = result.words.map((word) => ({
+        text: word.text,
+        confidence: word.confidence,
+        bbox: {
+          x0: Math.max(0, Math.min(1, word.bbox.x0 / rendered.canvas.width)),
+          y0: Math.max(0, Math.min(1, word.bbox.y0 / rendered.canvas.height)),
+          x1: Math.max(0, Math.min(1, word.bbox.x1 / rendered.canvas.width)),
+          y1: Math.max(0, Math.min(1, word.bbox.y1 / rendered.canvas.height)),
+        },
+      }));
       setPages((current) =>
         current.map((page) =>
           page.id === selected.id
@@ -410,6 +568,9 @@ export function Workbench() {
                 ...page,
                 ocrText: result.text,
                 ocrConfidence: result.confidence,
+                ocrWords,
+                ocrHocr: result.hocr,
+                ocrTsv: result.tsv,
               }
             : page,
         ),
@@ -418,17 +579,21 @@ export function Workbench() {
         `English OCR finished with ${result.confidence.toFixed(1)}% engine confidence.`,
       );
     } catch (reason) {
-      setError(
+      if (
-        `${reason instanceof Error ? reason.message : "OCR failed."} The page and previous text were retained.`,
+        !controller.signal.aborted &&
-      );
+        !(reason instanceof DOMException && reason.name === "AbortError")
+      )
+        setError(
+          `${reason instanceof Error ? reason.message : "OCR failed."} The page and previous text were retained.`,
+        );
     } finally {
-      setBusy(false);
+      finishProcessing(controller);
       setOcrProgress(undefined);
     }
   };
 
   const exportPdf = async () => {
-    setBusy(true);
+    const controller = beginProcessing("Preparing PDF export");
     setError(undefined);
     try {
       const pdf = await buildPdf(
@@ -437,15 +602,23 @@ export function Workbench() {
         pdfMargin,
         (completed, total) =>
           setNotice(`Rendering PDF page ${completed} of ${total}…`),
+        {
+          signal: controller.signal,
+          onProgress: reportProcessing,
+        },
       );
       triggerBlobDownload(pdf, "local-scan.pdf");
       setNotice(`Created a ${formatBytes(pdf.size)} image-only PDF locally.`);
     } catch (reason) {
-      setError(
+      if (
-        `${reason instanceof Error ? reason.message : "PDF export failed."} The workspace was retained.`,
+        !controller.signal.aborted &&
-      );
+        !(reason instanceof DOMException && reason.name === "AbortError")
+      )
+        setError(
+          `${reason instanceof Error ? reason.message : "PDF export failed."} The workspace was retained.`,
+        );
     } finally {
-      setBusy(false);
+      finishProcessing(controller);
     }
   };
 
@@ -478,6 +651,17 @@ export function Workbench() {
       <p className="status-line" role="status">
         {notice}
       </p>
+      {pixelProgress ? (
+        <div className="button-row" aria-live="polite">
+          <label>
+            {pixelProgress.stage}{" "}
+            <progress value={pixelProgress.value} max="1" />
+          </label>
+          <button type="button" onClick={cancelProcessing}>
+            Cancel processing
+          </button>
+        </div>
+      ) : null}
       {error ? (
         <p className="error" role="alert">
           {error}
@@ -732,18 +916,7 @@ export function Workbench() {
                       Recognize selected page
                     </button>
                     {busy && ocrProgress ? (
-                      <button
+                      <button type="button" onClick={cancelProcessing}>
-                        type="button"
-                        onClick={() =>
-                          void cancelOcr().catch((reason: unknown) =>
-                            setError(
-                              reason instanceof Error
-                                ? reason.message
-                                : "OCR cancellation failed.",
-                            ),
-                          )
-                        }
-                      >
                         Cancel OCR
                       </button>
                     ) : null}
@@ -791,6 +964,36 @@ export function Workbench() {
                   >
                     Download text
                   </button>
+                  {selected.ocrHocr ? (
+                    <button
+                      type="button"
+                      onClick={() =>
+                        triggerBlobDownload(
+                          new Blob([selected.ocrHocr ?? ""], {
+                            type: "text/html;charset=utf-8",
+                          }),
+                          `${selected.name.replace(/\.[^.]+$/u, "")}.hocr.html`,
+                        )
+                      }
+                    >
+                      Download hOCR geometry
+                    </button>
+                  ) : null}
+                  {selected.ocrTsv ? (
+                    <button
+                      type="button"
+                      onClick={() =>
+                        triggerBlobDownload(
+                          new Blob([selected.ocrTsv ?? ""], {
+                            type: "text/tab-separated-values;charset=utf-8",
+                          }),
+                          `${selected.name.replace(/\.[^.]+$/u, "")}.tsv`,
+                        )
+                      }
+                    >
+                      Download OCR TSV
+                    </button>
+                  ) : null}
                 </section>
               ) : null}
             </section>
@@ -829,9 +1032,32 @@ export function Workbench() {
             >
               Download {pages.length}-page PDF
             </button>
+            <button
+              type="button"
+              disabled={!pages.some((page) => page.ocrText)}
+              onClick={() =>
+                triggerBlobDownload(
+                  new Blob(
+                    [
+                      pages
+                        .map(
+                          (page, index) =>
+                            `--- Page ${index + 1}: ${page.name} ---\n${page.ocrText ?? ""}`,
+                        )
+                        .join("\n\n"),
+                    ],
+                    { type: "text/plain;charset=utf-8" },
+                  ),
+                  "local-scan-ocr.txt",
+                )
+              }
+            >
+              Download all OCR text
+            </button>
             <p className="microcopy">
-              The PDF is image-only in v0.1. OCR text downloads separately; no
+              The PDF stays image-only so text is never silently misaligned.
-              invisible text layer is guessed without reliable word geometry.
+              Positioned OCR can be inspected and exported separately as hOCR or
+              TSV.
             </p>
           </aside>
         </div>

src/scan/export.ts

@@ -1,5 +1,5 @@
 import { triggerBlobDownload } from "@add-ideas/toolbox-helpers";
-import { canvasBlob, renderPage } from "./render";
+import { canvasBlob, renderPage, type RenderTaskOptions } from "./render";
 import { MAX_EXPORT_PIXELS, type ScanPage } from "./types";
 
 export type PdfPageSize = "source" | "a4" | "letter";
@@ -7,8 +7,9 @@ export type PdfPageSize = "source" | "a4" | "letter";
 export async function exportImage(
   page: ScanPage,
   type: "image/png" | "image/jpeg",
+  options: RenderTaskOptions = {},
 ) {
-  const rendered = await renderPage(page, MAX_EXPORT_PIXELS);
+  const rendered = await renderPage(page, MAX_EXPORT_PIXELS, options);
   const blob = await canvasBlob(rendered.canvas, type);
   const extension = type === "image/png" ? "png" : "jpg";
   triggerBlobDownload(
@@ -32,12 +33,13 @@ export async function buildPdf(
   pageSize: PdfPageSize,
   marginPoints: number,
   onProgress: (completed: number, total: number) => void,
+  options: RenderTaskOptions = {},
 ): 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),
+    renderPage(pages[0]!, MAX_EXPORT_PIXELS, options),
   ]);
   const firstSize = pagePoints(
     pageSize,
@@ -53,7 +55,9 @@ export async function buildPdf(
   });
   for (let index = 0; index < pages.length; index += 1) {
     const rendered =
-      index === 0 ? first : await renderPage(pages[index]!, MAX_EXPORT_PIXELS);
+      index === 0
+        ? first
+        : await renderPage(pages[index]!, MAX_EXPORT_PIXELS, options);
     const dimensions = pagePoints(
       pageSize,
       rendered.canvas.width,
@@ -85,6 +89,8 @@ export async function buildPdf(
       "FAST",
     );
     onProgress(index + 1, pages.length);
+    if (options.signal?.aborted)
+      throw new DOMException("PDF export cancelled.", "AbortError");
     await new Promise<void>((resolve) =>
       requestAnimationFrame(() => resolve()),
     );

src/scan/ocr.ts

@@ -1,4 +1,4 @@
-import type { Worker } from "tesseract.js";
+import type { Bbox, Worker } from "tesseract.js";
 
 let activeWorker: Worker | undefined;
 let creation: Promise<Worker> | undefined;
@@ -38,10 +38,39 @@ async function worker(onProgress: (status: string, progress: number) => void) {
 export async function recognizeEnglish(
   image: Blob,
   onProgress: (status: string, progress: number) => void,
-): Promise<{ text: string; confidence: number }> {
+): Promise<{
+  text: string;
+  confidence: number;
+  words: Array<{ text: string; confidence: number; bbox: Bbox }>;
+  hocr: string;
+  tsv: string;
+}> {
   const instance = await worker(onProgress);
-  const result = await instance.recognize(image);
+  const result = await instance.recognize(
-  return { text: result.data.text, confidence: result.data.confidence };
+    image,
+    {},
+    { text: true, blocks: true, hocr: true, tsv: true },
+  );
+  const words: Array<{ text: string; confidence: number; bbox: Bbox }> = [];
+  for (const block of result.data.blocks ?? [])
+    for (const paragraph of block.paragraphs)
+      for (const line of paragraph.lines)
+        for (const word of line.words)
+          if (word.text.trim())
+            words.push({
+              text: word.text.slice(0, 500),
+              confidence: word.confidence,
+              bbox: word.bbox,
+            });
+  if (words.length > 100_000)
+    throw new RangeError("OCR produced more than 100,000 positioned words.");
+  return {
+    text: result.data.text,
+    confidence: result.data.confidence,
+    words,
+    hocr: result.data.hocr ?? "",
+    tsv: result.data.tsv ?? "",
+  };
 }
 
 export async function cancelOcr(): Promise<void> {

src/scan/render.ts

@@ -6,7 +6,12 @@ import {
   type ScanPage,
 } from "./types";
 
-const MAX_WORKING_SOURCE_PIXELS = 24_000_000;
+export const MAX_WORKING_SOURCE_PIXELS = 24_000_000;
+
+export interface RenderTaskOptions {
+  signal?: AbortSignal;
+  onProgress?: (progress: number, stage: string) => void;
+}
 
 function canvas(width: number, height: number): HTMLCanvasElement {
   const element = document.createElement("canvas");
@@ -61,7 +66,7 @@ function sampleBilinear(
   return top * (1 - fy) + bottom * fy;
 }
 
-function perspectiveCorrect(
+export function perspectiveCorrectPixels(
   source: ImageData,
   outputWidth: number,
   outputHeight: number,
@@ -156,9 +161,16 @@ export interface RenderedPage {
 export async function renderPage(
   page: ScanPage,
   maximumPixels: number,
+  options: RenderTaskOptions = {},
 ): Promise<RenderedPage> {
+  if (canRenderInWorker())
+    return renderPageInWorker(page, maximumPixels, options);
+  throwIfAborted(options.signal);
+  options.onProgress?.(0.05, "Decoding page");
   const bitmap = await createImageBitmap(page.source);
   try {
+    throwIfAborted(options.signal);
+    options.onProgress?.(0.2, "Preparing source pixels");
     const sourceScale = Math.min(
       1,
       Math.sqrt(MAX_WORKING_SOURCE_PIXELS / (bitmap.width * bitmap.height)),
@@ -183,7 +195,7 @@ export async function renderPage(
     );
     const corrected = canvas(dimensions.width, dimensions.height);
     context(corrected).putImageData(
-      perspectiveCorrect(
+      perspectiveCorrectPixels(
         sourceContext.getImageData(
           0,
           0,
@@ -197,23 +209,34 @@ export async function renderPage(
       0,
       0,
     );
+    throwIfAborted(options.signal);
+    options.onProgress?.(0.8, "Rotating corrected page");
     const rotated = rotate(
       corrected,
       page.adjustments.quarterTurns * 90 + page.adjustments.deskew,
     );
-    return {
+    const result = {
       canvas: boundPixels(rotated, maximumPixels),
       sourceScale,
       outputScale: dimensions.scale,
     };
+    options.onProgress?.(1, "Page ready");
+    return result;
   } finally {
     bitmap.close();
   }
 }
 
-export async function detectDeskew(page: ScanPage): Promise<number> {
+export async function detectDeskew(
+  page: ScanPage,
+  options: RenderTaskOptions = {},
+): Promise<number> {
+  if (canRenderInWorker()) return detectDeskewInWorker(page, options);
+  throwIfAborted(options.signal);
+  options.onProgress?.(0.1, "Decoding deskew sample");
   const bitmap = await createImageBitmap(page.source);
   try {
+    throwIfAborted(options.signal);
     const scale = Math.min(1, 420 / Math.max(bitmap.width, bitmap.height));
     const work = canvas(
       Math.max(16, Math.round(bitmap.width * scale)),
@@ -221,16 +244,142 @@ export async function detectDeskew(page: ScanPage): Promise<number> {
     );
     const workContext = context(work);
     workContext.drawImage(bitmap, 0, 0, work.width, work.height);
-    return estimateDeskew(
+    options.onProgress?.(0.5, "Scoring text-line angles");
+    const angle = estimateDeskew(
       workContext.getImageData(0, 0, work.width, work.height).data,
       work.width,
       work.height,
     );
+    throwIfAborted(options.signal);
+    options.onProgress?.(1, "Deskew estimate ready");
+    return angle;
   } finally {
     bitmap.close();
   }
 }
 
+interface RenderWorkerResponse {
+  id: number;
+  kind: "progress" | "render" | "deskew" | "error";
+  progress?: number;
+  stage?: string;
+  bitmap?: ImageBitmap;
+  width?: number;
+  height?: number;
+  sourceScale?: number;
+  outputScale?: number;
+  angle?: number;
+  error?: string;
+}
+
+let nextWorkerId = 0;
+
+function canRenderInWorker(): boolean {
+  return (
+    typeof Worker !== "undefined" && typeof OffscreenCanvas !== "undefined"
+  );
+}
+
+function renderPageInWorker(
+  page: ScanPage,
+  maximumPixels: number,
+  options: RenderTaskOptions,
+): Promise<RenderedPage> {
+  return runRenderWorker(
+    {
+      task: "render",
+      source: page.source,
+      adjustments: page.adjustments,
+      maximumPixels,
+    },
+    options,
+  ).then((message) => {
+    if (!message.bitmap || !message.width || !message.height)
+      throw new Error("Scan worker returned no rendered page.");
+    const output = canvas(message.width, message.height);
+    context(output).drawImage(message.bitmap, 0, 0);
+    message.bitmap.close();
+    return {
+      canvas: output,
+      sourceScale: message.sourceScale ?? 1,
+      outputScale: message.outputScale ?? 1,
+    };
+  });
+}
+
+function detectDeskewInWorker(
+  page: ScanPage,
+  options: RenderTaskOptions,
+): Promise<number> {
+  return runRenderWorker({ task: "deskew", source: page.source }, options).then(
+    (message) => {
+      if (typeof message.angle !== "number")
+        throw new Error("Scan worker returned no deskew angle.");
+      return message.angle;
+    },
+  );
+}
+
+function runRenderWorker(
+  request:
+    | {
+        task: "render";
+        source: File;
+        adjustments: PageAdjustments;
+        maximumPixels: number;
+      }
+    | { task: "deskew"; source: File },
+  options: RenderTaskOptions,
+): Promise<RenderWorkerResponse> {
+  throwIfAborted(options.signal);
+  const id = ++nextWorkerId;
+  const worker = new Worker(new URL("./render.worker.ts", import.meta.url), {
+    type: "module",
+  });
+  return new Promise((resolve, reject) => {
+    let settled = false;
+    const finish = () => {
+      settled = true;
+      worker.terminate();
+      options.signal?.removeEventListener("abort", abort);
+    };
+    const abort = () => {
+      if (settled) return;
+      finish();
+      reject(abortError());
+    };
+    options.signal?.addEventListener("abort", abort, { once: true });
+    worker.onmessage = (event: MessageEvent<RenderWorkerResponse>) => {
+      if (event.data.id !== id || settled) return;
+      if (event.data.kind === "progress") {
+        options.onProgress?.(
+          event.data.progress ?? 0,
+          event.data.stage ?? "Processing page",
+        );
+        return;
+      }
+      finish();
+      if (event.data.kind === "error")
+        reject(new Error(event.data.error ?? "Scan worker failed."));
+      else resolve(event.data);
+    };
+    worker.onerror = () => {
+      if (settled) return;
+      finish();
+      reject(new Error("Scan worker failed to start."));
+    };
+    worker.postMessage({ id, ...request });
+  });
+}
+
+function throwIfAborted(signal?: AbortSignal): void {
+  if (signal?.aborted) throw abortError();
+}
+
+function abortError(): DOMException {
+  return new DOMException("Page processing cancelled.", "AbortError");
+}
+
 export function canvasBlob(
   source: HTMLCanvasElement,
   type: "image/png" | "image/jpeg",

src/scan/render.worker.ts

@@ -0,0 +1,185 @@
+/// <reference lib="webworker" />
+
+import { correctedDimensions } from "./geometry";
+import { estimateDeskew } from "./pixels";
+import { MAX_WORKING_SOURCE_PIXELS, perspectiveCorrectPixels } from "./render";
+import { MAX_SOURCE_PIXELS, type PageAdjustments } from "./types";
+
+type Request =
+  | {
+      id: number;
+      task: "render";
+      source: File;
+      adjustments: PageAdjustments;
+      maximumPixels: number;
+    }
+  | { id: number; task: "deskew"; source: File };
+
+declare const self: DedicatedWorkerGlobalScope;
+
+self.onmessage = (event: MessageEvent<Request>) => {
+  void run(event.data);
+};
+
+async function run(request: Request): Promise<void> {
+  try {
+    progress(request.id, 0.05, "Decoding page");
+    const bitmap = await createImageBitmap(request.source);
+    try {
+      if (bitmap.width * bitmap.height > MAX_SOURCE_PIXELS)
+        throw new RangeError(
+          `Decoded image exceeds ${MAX_SOURCE_PIXELS.toLocaleString()} pixels.`,
+        );
+      if (request.task === "deskew") {
+        const angle = renderDeskewSample(request.id, bitmap);
+        self.postMessage({ id: request.id, kind: "deskew", angle });
+      } else {
+        const result = await render(
+          request.id,
+          bitmap,
+          request.adjustments,
+          request.maximumPixels,
+        );
+        self.postMessage({ id: request.id, kind: "render", ...result }, [
+          result.bitmap,
+        ]);
+      }
+    } finally {
+      bitmap.close();
+    }
+  } catch (reason) {
+    self.postMessage({
+      id: request.id,
+      kind: "error",
+      error:
+        reason instanceof Error ? reason.message : "Page processing failed.",
+    });
+  }
+}
+
+async function render(
+  id: number,
+  bitmap: ImageBitmap,
+  adjustments: PageAdjustments,
+  maximumPixels: number,
+) {
+  progress(id, 0.15, "Preparing source pixels");
+  const sourceScale = Math.min(
+    1,
+    Math.sqrt(MAX_WORKING_SOURCE_PIXELS / (bitmap.width * bitmap.height)),
+  );
+  const source = makeCanvas(
+    Math.max(1, Math.round(bitmap.width * sourceScale)),
+    Math.max(1, Math.round(bitmap.height * sourceScale)),
+  );
+  const sourceContext = context(source);
+  sourceContext.drawImage(bitmap, 0, 0, source.width, source.height);
+  const dimensions = correctedDimensions(
+    adjustments.quad,
+    source.width,
+    source.height,
+    maximumPixels,
+  );
+  progress(id, 0.3, "Correcting perspective and pixels");
+  const corrected = makeCanvas(dimensions.width, dimensions.height);
+  context(corrected).putImageData(
+    perspectiveCorrectPixels(
+      sourceContext.getImageData(0, 0, source.width, source.height),
+      dimensions.width,
+      dimensions.height,
+      adjustments,
+    ),
+    0,
+    0,
+  );
+  progress(id, 0.8, "Rotating corrected page");
+  const rotated = rotate(
+    corrected,
+    adjustments.quarterTurns * 90 + adjustments.deskew,
+  );
+  const bounded = boundPixels(rotated, maximumPixels);
+  const result = await createImageBitmap(bounded);
+  progress(id, 1, "Page ready");
+  return {
+    bitmap: result,
+    width: bounded.width,
+    height: bounded.height,
+    sourceScale,
+    outputScale: dimensions.scale,
+  };
+}
+
+function renderDeskewSample(id: number, bitmap: ImageBitmap): number {
+  progress(id, 0.25, "Preparing deskew sample");
+  const scale = Math.min(1, 420 / Math.max(bitmap.width, bitmap.height));
+  const work = makeCanvas(
+    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);
+  progress(id, 0.5, "Scoring text-line angles");
+  const angle = estimateDeskew(
+    workContext.getImageData(0, 0, work.width, work.height).data,
+    work.width,
+    work.height,
+  );
+  progress(id, 1, "Deskew estimate ready");
+  return angle;
+}
+
+function makeCanvas(width: number, height: number): OffscreenCanvas {
+  return new OffscreenCanvas(width, height);
+}
+
+function context(canvas: OffscreenCanvas): OffscreenCanvasRenderingContext2D {
+  const value = canvas.getContext("2d", { willReadFrequently: true });
+  if (!value)
+    throw new Error("This browser could not create an offscreen 2D canvas.");
+  return value;
+}
+
+function rotate(source: OffscreenCanvas, degrees: number): OffscreenCanvas {
+  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 = makeCanvas(width, height);
+  const target = context(output);
+  target.fillStyle = "white";
+  target.fillRect(0, 0, width, height);
+  target.translate(width / 2, height / 2);
+  target.rotate(radians);
+  target.drawImage(source, -source.width / 2, -source.height / 2);
+  return output;
+}
+
+function boundPixels(
+  source: OffscreenCanvas,
+  maximumPixels: number,
+): OffscreenCanvas {
+  if (source.width * source.height <= maximumPixels) return source;
+  const scale = Math.sqrt(maximumPixels / (source.width * source.height));
+  const output = makeCanvas(
+    Math.max(16, Math.floor(source.width * scale)),
+    Math.max(16, Math.floor(source.height * scale)),
+  );
+  const target = context(output);
+  target.imageSmoothingEnabled = true;
+  target.imageSmoothingQuality = "high";
+  target.drawImage(source, 0, 0, output.width, output.height);
+  return output;
+}
+
+function progress(id: number, value: number, stage: string): void {
+  self.postMessage({ id, kind: "progress", progress: value, stage });
+}
+
+export {};

src/scan/types.ts

@@ -33,6 +33,16 @@ export interface ScanPage {
   adjustments: PageAdjustments;
   ocrText?: string;
   ocrConfidence?: number;
+  ocrWords?: OcrWord[];
+  ocrHocr?: string;
+  ocrTsv?: string;
+}
+
+export interface OcrWord {
+  text: string;
+  confidence: number;
+  /** Normalized bounds in the corrected OCR image. */
+  bbox: { x0: number; y0: number; x1: number; y1: number };
 }
 
 export const DEFAULT_QUAD: Quad = [

src/styles.css

@@ -309,9 +309,46 @@ button:disabled {
   text-anchor: middle;
   dominant-baseline: central;
 }
+.corner-fields {
+  display: grid;
+  grid-template-columns: repeat(4, minmax(0, 1fr));
+  gap: 0.4rem;
+  margin-top: 0.55rem;
+}
+.corner-fields fieldset {
+  min-width: 0;
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 0.35rem;
+  margin: 0;
+  padding: 0.45rem;
+  border: 1px solid var(--scan-line);
+  border-radius: 0.55rem;
+}
+.corner-fields legend {
+  padding: 0 0.2rem;
+  color: var(--scan-muted);
+  font-size: 0.68rem;
+  font-weight: 750;
+}
+.corner-fields input {
+  width: 100%;
+  min-width: 0;
+}
 .processed-stage {
   min-height: 12rem;
 }
+.processed-image {
+  position: relative;
+  display: grid;
+  place-items: center;
+  max-width: 100%;
+  max-height: 28rem;
+}
+.processed-image canvas,
+.processed-image .ocr-overlay {
+  grid-area: 1 / 1;
+}
 .processed-stage canvas {
   display: block;
   max-width: 100%;
@@ -319,6 +356,18 @@ button:disabled {
   width: auto;
   height: auto;
 }
+.ocr-overlay {
+  z-index: 1;
+  width: 100%;
+  height: 100%;
+  pointer-events: none;
+}
+.ocr-overlay rect {
+  fill: color-mix(in srgb, var(--scan-accent) 8%, transparent);
+  stroke: #00e3b4;
+  stroke-width: 0.2;
+  vector-effect: non-scaling-stroke;
+}
 
 .controls-grid {
   display: grid;
@@ -429,6 +478,9 @@ button:disabled {
 }
 
 @media (max-width: 72rem) {
+  .corner-fields {
+    grid-template-columns: repeat(2, minmax(0, 1fr));
+  }
   .workspace-grid {
     grid-template-columns: 14rem minmax(0, 1fr);
   }
@@ -474,7 +526,8 @@ button:disabled {
     flex-direction: column;
   }
   .controls-grid,
-  .export-card {
+  .export-card,
+  .corner-fields {
     grid-template-columns: 1fr;
   }
   .export-card > :is(.eyebrow, h2, .microcopy) {

src/toolbox/manifest.source.json

@@ -3,12 +3,12 @@
   "schemaVersion": 1,
   "id": "de.add-ideas.scan-tools",
   "name": "Scan Tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Correct, assemble, recognize and export scanned pages locally.",
   "entry": "./",
   "icon": "./favicon.svg",
   "categories": ["document", "image", "productivity"],
-  "tags": ["scan", "camera", "deskew", "perspective", "ocr", "pdf"],
+  "tags": ["scan", "camera", "deskew", "perspective", "ocr", "hocr", "pdf"],
   "integration": {
     "contextVersion": 1,
     "launchModes": ["navigate", "new-tab"],
@@ -16,11 +16,30 @@
   },
   "requirements": {
     "secureContext": false,
-    "workers": true,
+    "workers": false,
     "indexedDb": false,
     "crossOriginIsolated": false,
     "topLevelContext": false
   },
+  "io": {
+    "accepts": [
+      { "mediaType": "image/png", "extensions": [".png"] },
+      { "mediaType": "image/jpeg", "extensions": [".jpg", ".jpeg"] },
+      { "mediaType": "image/webp", "extensions": [".webp"] }
+    ],
+    "produces": [
+      { "mediaType": "image/png", "extensions": [".png"] },
+      { "mediaType": "image/jpeg", "extensions": [".jpg"] },
+      { "mediaType": "application/pdf", "extensions": [".pdf"] },
+      { "mediaType": "text/plain", "extensions": [".txt"] },
+      { "mediaType": "text/html", "extensions": [".hocr.html"] },
+      { "mediaType": "text/tab-separated-values", "extensions": [".tsv"] }
+    ]
+  },
+  "capabilities": {
+    "required": [],
+    "optional": ["workers", "offscreen-canvas", "webassembly", "camera-capture"]
+  },
   "privacy": {
     "processing": "local",
     "fileUploads": true,

src/version.ts

@@ -1 +1 @@
-export const APP_VERSION = "0.1.0";
+export const APP_VERSION = "0.2.0";

tests/browser/app.spec.ts

@@ -82,6 +82,11 @@ test("adds and corrects a real local image while retaining the previous preview"
     "aria-valuetext",
     /^1% from left/u,
   );
+  await page.getByLabel("Corner 2 X (%)").fill("98.5");
+  await expect(page.getByRole("slider", { name: "Corner 2" })).toHaveAttribute(
+    "aria-valuetext",
+    /^99% from left/u,
+  );
   const download = page.waitForEvent("download");
   await page.getByRole("button", { name: "Download PNG" }).click();
   expect((await download).suggestedFilename()).toBe("page-scan.png");
@@ -156,6 +161,13 @@ test("runs the bundled OCR engine without an external request", async ({
     timeout: 90_000,
   });
   await expect(page.getByLabel("Recognized text")).toContainText(/LOCAL|SCAN/u);
+  await expect(page.getByLabel(/positioned OCR words/u)).toBeVisible();
+  await expect(
+    page.getByRole("button", { name: "Download hOCR geometry" }),
+  ).toBeVisible();
+  await expect(
+    page.getByRole("button", { name: "Download OCR TSV" }),
+  ).toBeVisible();
   expect(external).toEqual([]);
 });
 
@@ -191,8 +203,12 @@ test("integrates help, themes, identity, headers and offline reload", async ({
   );
   await expect(manifest.json()).resolves.toMatchObject({
     id: "de.add-ideas.scan-tools",
-    version: "0.1.0",
+    version: "0.2.0",
-    requirements: { workers: true },
+    requirements: { workers: false },
+    capabilities: {
+      required: [],
+      optional: expect.arrayContaining(["workers"]),
+    },
     privacy: { processing: "local", telemetry: false },
   });
   await context.setOffline(true);

tests/browser/responsive.spec.ts

@@ -0,0 +1,18 @@
+import { expect, test } from "@playwright/test";
+
+test("keeps the primary workspace inside a narrow viewport", async ({
+  page,
+}) => {
+  await page.goto("/deep/nested/scan-tools/");
+  await expect(page.locator("main").first()).toBeVisible();
+  await expect(
+    page.locator("main .loading, main .workbench-loading"),
+  ).toHaveCount(0);
+
+  const widths = await page.evaluate(() => ({
+    content: document.documentElement.scrollWidth,
+    viewport: document.documentElement.clientWidth,
+  }));
+  expect(widths.viewport).toBeLessThanOrEqual(430);
+  expect(widths.content).toBeLessThanOrEqual(widths.viewport + 1);
+});

tests/scan/render.test.ts

@@ -0,0 +1,28 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { perspectiveCorrectPixels } from "../../src/scan/render";
+import { defaultAdjustments } from "../../src/scan/types";
+
+class TestImageData {
+  data: Uint8ClampedArray;
+  width: number;
+  height: number;
+  constructor(width: number, height: number) {
+    this.width = width;
+    this.height = height;
+    this.data = new Uint8ClampedArray(width * height * 4);
+  }
+}
+
+describe("scan render core", () => {
+  afterEach(() => vi.unstubAllGlobals());
+
+  it("maps an identity quad without changing corner colours", () => {
+    vi.stubGlobal("ImageData", TestImageData);
+    const source = new TestImageData(2, 2) as unknown as ImageData;
+    source.data.set([
+      255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 255, 255, 255, 255, 255, 255,
+    ]);
+    const result = perspectiveCorrectPixels(source, 2, 2, defaultAdjustments());
+    expect([...result.data]).toEqual([...source.data]);
+  });
+});