Release Diff Tools 0.2.0

2026-09-02 04:43:16 +02:00
parent a1380cfba2
commit 46fc10f745
37 changed files with 2722 additions and 455 deletions
@@ -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
@@ -1,5 +1,18 @@
 # Changelog
 ## 0.2.0 - 2026-09-02
 - Adopted `@add-ideas/toolbox-helpers` 0.2.0 for deterministic byte-size
  display, safe Blob downloads and the shared worker-job protocol.
 - Added a 15-second hard disposable-worker deadline with a distinct structured
  diagnostic while retaining the algorithm-level two-second diff budget.
 - Added bounded local directory manifests with collision-safe relative paths,
  two-file SHA-256 concurrency, progress, cancellation and portable comparison.
 - Added bounded line-oriented three-way merge with non-overlap combination,
  explicit ours/base/theirs conflicts and a machine-readable merge report.
 - Retained loss-aware semantic JSON, CSV/TSV and hardened XML comparisons beside
  the new directory and merge workspaces.
 ## 0.1.0 - 2026-09-01
 - Added line, word, code-point and grapheme text comparison with exact newline state and unified patch export.
@@ -2,23 +2,25 @@
 Compare text and structured data locally in the browser.
-Diff Tools is a standalone, local-first application in the [add·ideas Toolbox](https://git.add-ideas.de/lotobo/toolbox-portal). Inputs are processed in a disposable browser worker and are never uploaded by the application.
+Diff Tools is a standalone, local-first application in the [add·ideas Toolbox](https://git.add-ideas.de/lotobo/toolbox-portal). Inputs are processed through the shared cancellable disposable-worker protocol, with an algorithm budget and a 15-second hard worker deadline, and are never uploaded by the application.
-## Version 0.1 scope
+## Version 0.2 scope
 - Text diff by line, word, Unicode code point or grapheme cluster, with exact LF, CRLF, CR and final-newline state.
 - Explicit text comparison rules for case, whitespace, line endings, final newline and Unicode normalization. Normalized differences stay visible.
 - Semantic JSON comparison with duplicate-key rejection, exact decimal numbers, object-order reporting and RFC 6902 output when representable.
 - Namespace-aware XML comparison with visible prefix, attribute-order, comment, whitespace and CDATA normalization. DOCTYPE, entity declarations and XInclude are rejected.
 - CSV and TSV comparison by one or more unique key columns, including duplicate-key diagnostics, string-preserving fields and visible column/row order changes.
 - Build deterministic relative-path directory manifests with local SHA-256 hashing, bounded two-file concurrency and conservative collision checks; export/import manifests and compare them without retaining file contents.
 - Perform a bounded, line-preserving three-way text merge from base/ours/theirs, with non-overlapping edits combined and explicit ours/base/theirs markers plus a JSON report for every conflict.
 - Unified and side-by-side views, an exact unified text patch and a portable, versioned JSON report.
 - Stable-last-result interaction: invalid or unfinished input does not blank the previous successful result.
-This version intentionally does not compare images, binary documents, directories or archives.
+This version does not interpret images, binary documents or archives. Directory comparison is content-digest based and cannot represent empty directories because browser directory selection exposes files only. Three-way merge is textual rather than a semantic JSON/XML merge.
 ## Safety limits
-Each input is limited to 8 MiB and 4 million characters. Parsing and output also have explicit row, cell, token, node, nesting, edit-count, time and display limits. Imported values are rendered as React text nodes; parser-provided HTML is never inserted. See [privacy and security](docs/PRIVACY-SECURITY.md).
+Each ordinary or merge input is limited to 8 MiB and 4 million characters. Directory manifests are limited to 5,000 files, 512 MiB total, 256 MiB per file, 4,096-character relative paths and two concurrent hashes. Parsing and output also have explicit row, cell, token, node, nesting, edit-count, conflict-count, time and display limits. Imported values are rendered as React text nodes; parser-provided HTML is never inserted. See [privacy and security](docs/PRIVACY-SECURITY.md).
 ## Development
@@ -38,7 +40,7 @@ The browser suite builds and serves the app below `/deep/nested/diff/`, blocks e
 npm run release:artifact
 ```
-This creates deterministic `release/diff-tools-0.1.0.zip` and `.sha256` files after all validation gates pass.
+This creates deterministic `release/diff-tools-0.2.0.zip` and `.sha256` files after all validation gates pass.
 ## Licence
@@ -1,7 +1,7 @@
 # Corresponding source
-The corresponding source for Diff Tools 0.1.0 is available at:
+The corresponding source for Diff Tools 0.2.0 is available at:
-https://git.add-ideas.de/lotobo/diff-tools/src/tag/v0.1.0
+https://git.add-ideas.de/lotobo/diff-tools/src/tag/v0.2.0
 Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.
@@ -2,14 +2,15 @@
 Diff Tools is GPL-3.0-or-later. Its direct runtime dependencies retain their own licences:
-| Package                          | Pinned version | Licence      | Purpose                                        |
+| Package                          | Pinned version | Licence          | Purpose                                        |
-| -------------------------------- | -------------: | ------------ | ---------------------------------------------- |
+| -------------------------------- | -------------: | ---------------- | ---------------------------------------------- |
-| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0   | Manifest validation                            |
+| `@add-ideas/toolbox-contract`    |          0.3.0 | Apache-2.0       | Manifest validation                            |
-| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0   | Shared Toolbox shell                           |
+| `@add-ideas/toolbox-helpers`     |          0.2.0 | GPL-3.0-or-later | Shared local-first utility primitives          |
-| `@xmldom/xmldom`                 |         0.9.12 | MIT          | Inert XML DOM parsing                          |
+| `@add-ideas/toolbox-shell-react` |          0.3.0 | Apache-2.0       | Shared Toolbox shell                           |
-| `diff`                           |          9.0.0 | BSD-3-Clause | Bounded sequence alignment and unified patches |
+| `@xmldom/xmldom`                 |         0.9.12 | MIT              | Inert XML DOM parsing                          |
-| `lossless-json`                  |          4.3.1 | MIT          | Exact-decimal JSON parsing and serialization   |
+| `diff`                           |          9.0.0 | BSD-3-Clause     | Bounded sequence alignment and unified patches |
-| `papaparse`                      |          5.7.0 | MIT          | CSV and TSV parsing                            |
+| `lossless-json`                  |          4.3.1 | MIT              | Exact-decimal JSON parsing and serialization   |
-| `react` / `react-dom`            |         19.2.8 | MIT          | User interface                                 |
+| `papaparse`                      |          5.7.0 | MIT              | CSV and TSV parsing                            |
 | `react` / `react-dom`            |         19.2.8 | MIT              | User interface                                 |
 Release artifacts include the complete licence texts collected from every locked runtime package at `LICENSES/npm-runtime-licenses.txt`.
@@ -1,6 +1,6 @@
 # Accessibility
-The workbench uses labelled native text areas, selects, checkboxes, file inputs and buttons. Comparison modes and result views are exposed as tab lists, status and diagnostic changes use live regions, and structured results use list or table semantics.
+The workbench uses labelled native text areas, selects, checkboxes, file inputs and buttons. Comparison modes and result views are exposed as labelled pressed-state button groups, status and diagnostic changes use live regions, and structured results use list or table semantics.
 Change kinds are written in text and indicated by `+`/`−` markers, not colour alone. Exact CR, LF and tab characters have visible glyphs. Focus indicators remain visible in light, dark and system themes, and controls meet a minimum 2.55 rem target height.
@@ -3,7 +3,10 @@
 Diff Tools is a static React application with a relocatable `./` build. Its comparison pipeline is deliberately separated from the view:
 1. The workbench captures strings or decodes a selected file as strict UTF-8 after a byte-size check.
-2. A fresh module worker receives a plain comparison request. Changing input cancels and terminates the preceding worker; the last successful result remains on screen until a replacement succeeds.
+2. A fresh module worker receives a typed shared worker-job request. Changing
   input cancels and terminates the preceding worker; job IDs exclude stale
   messages, and a 15-second hard deadline bounds the whole worker. The last
   successful result remains on screen until a replacement succeeds.
 3. A mode-specific pure comparator produces display rows and diagnostics. Normalized rows are first-class output, not discarded state.
 4. The orchestrator adds exact input metadata, a bounded unified patch and a schema-labelled portable report.
 5. React renders values as text. The app never consumes or inserts HTML produced by a diff or parser library.
@@ -16,7 +19,11 @@ When `Worker` is unavailable, such as in unit tests, the same pure comparator ru
 - JSON uses `lossless-json`, rejects duplicate and prototype-affecting keys, and compares numbers without converting to IEEE-754. Object member order is semantically ignored but reported.
 - XML rejects active declaration/include syntax and preflights structure before `@xmldom/xmldom` builds an inert DOM. Elements and attributes compare by expanded name when selected.
 - CSV/TSV uses Papa Parse in string mode. Unique composite keys align rows; no spreadsheet type inference is performed.
 - Directory manifests strip the one common browser-selected root, validate every relative path and conservative case/Unicode collision key, then hash file bytes with SHA-256 under count, per-file, aggregate and concurrency ceilings. The sorted, versioned JSON artifact can be compared later without the files.
 - Three-way merge independently derives bounded token edits from base to ours and base to theirs. Non-overlapping regions compose; overlapping regions are compared against each other and the base before conflict markers are emitted. It does not claim semantic structured-data merging.
-All report and patch formats are generated locally. `de.add-ideas.diff-tools.report.v1` is the portable report schema identifier.
+All report and patch formats are generated locally. `de.add-ideas.diff-tools.report.v1`, `de.add-ideas.diff-tools.directory-manifest.v1` and `de.add-ideas.diff-tools.merge-report.v1` identify the portable artifacts.
-The planned shared `@add-ideas/toolbox-helpers` package is not yet published at a compatible version, so v0.1 keeps its bounded domain functions inside `src/core`. They can be extracted without changing the worker protocol or report schema.
+Diff algorithms, semantic models and reports remain bounded domain functions in
 `src/core`. Generic byte-size display, safe Blob downloads and cancellable
 worker lifecycle come from `@add-ideas/toolbox-helpers` 0.2.0.
@@ -13,6 +13,9 @@ The production CSP permits same-origin scripts and workers and blocks objects, f
 - XML containing DOCTYPE, entity declaration or XInclude syntax is rejected before DOM parsing. A lexical preflight rejects excessive element count or nesting before DOM construction.
 - JSON rejects duplicate keys and the prototype-affecting keys `__proto__`, `prototype` and `constructor`.
 - CSV/TSV fields remain strings; formulas are displayed as text and are not evaluated.
 - Directory hashing rejects traversal, absolute/control-laden and case/Unicode-colliding relative paths. SHA-256 reads use bounded concurrency, file/count/aggregate ceilings and an abort signal.
 - Imported manifests are schema-, path-, digest-, order- and total-validated before comparison. Directory names and digests are sensitive metadata and should be reviewed before sharing.
 - Three-way inputs use the same text ceilings plus an explicit conflict cap; conflict labels have CR/LF removed before entering marker lines.
 - Imported strings are rendered through React text nodes and form controls. No library-generated HTML, imported markup or script is inserted into the document.
 These controls bound this tool's work; they are not a general-purpose sanitizer and do not make imported data safe for another application.
@@ -1,16 +1,17 @@
 {
  "name": "diff-tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "diff-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-shell-react": "0.2.3",
+        "@add-ideas/toolbox-helpers": "0.2.0",
        "@add-ideas/toolbox-shell-react": "0.3.0",
        "@xmldom/xmldom": "0.9.12",
        "diff": "9.0.0",
        "lossless-json": "4.3.1",
@@ -19,7 +20,7 @@
        "react-dom": "19.2.8"
      },
      "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",
@@ -46,18 +47,25 @@
      }
    },
    "node_modules/@add-ideas/toolbox-contract": {
-      "version": "0.2.3",
+      "version": "0.3.0",
-      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-contract/-/0.2.3/toolbox-contract-0.2.3.tgz",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-contract/-/0.3.0/toolbox-contract-0.3.0.tgz",
-      "integrity": "sha512-T0PVSuMT40GjTDfQJhEEY3ZawQq8zz1/ry95JdKI6W39CdLacaRXdGnEpDCMHt+jUbf1Jz7Nat/M5dFCgKVM9A==",
+      "integrity": "sha512-dKrK7BjOFwqJaBfJuhKxZKIld4sH0AKjEn6a0yLnbdMUFY+fFv4VSLGV2tNSBD016gumc2iNqOjUj/ld7x4rtA==",
      "license": "Apache-2.0"
    },
    "node_modules/@add-ideas/toolbox-helpers": {
      "version": "0.2.0",
      "license": "GPL-3.0-or-later",
      "engines": {
        "node": ">=22"
      }
    },
    "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/-/0.2.3/toolbox-shell-react-0.2.3.tgz",
+      "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-DT5lQDH48BFkFcmFLZnQh7+Cm73JzBPcmp5WzUXypfkUXpEyDYHzaXgmW4kZ0edSwh4RK4sPmx+JPtK0X4aKCQ==",
+      "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",
@@ -65,13 +73,13 @@
      }
    },
    "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/-/0.2.3/toolbox-testkit-0.2.3.tgz",
+      "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-sq1MwhKWfFKen+N+124hl74qQimRSvmQ9sOU7jdcI+2qCKZ67+2B8rWyezeV80uTFu4Jv6deHksfYQ/tKNV6XQ==",
+      "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"
@@ -1,7 +1,7 @@
 {
  "name": "diff-tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
-  "description": "Compare text and structured data locally in the browser.",
+  "description": "Compare files and directories or perform bounded three-way merges locally.",
  "license": "GPL-3.0-or-later",
  "author": "Albrecht Degering",
  "repository": {
@@ -39,8 +39,9 @@
    "release:artifact": "npm run check && npm run test:browser && npm run package:release -- --force"
  },
  "dependencies": {
-    "@add-ideas/toolbox-contract": "0.2.3",
+    "@add-ideas/toolbox-contract": "0.3.0",
-    "@add-ideas/toolbox-shell-react": "0.2.3",
+    "@add-ideas/toolbox-helpers": "0.2.0",
    "@add-ideas/toolbox-shell-react": "0.3.0",
    "@xmldom/xmldom": "0.9.12",
    "diff": "9.0.0",
    "lossless-json": "4.3.1",
@@ -49,7 +50,7 @@
    "react-dom": "19.2.8"
  },
  "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",
@@ -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"] },
    },
  ],
 });
@@ -1,5 +1,18 @@
 # Changelog
 ## 0.2.0 - 2026-09-02
 - Adopted `@add-ideas/toolbox-helpers` 0.2.0 for deterministic byte-size
  display, safe Blob downloads and the shared worker-job protocol.
 - Added a 15-second hard disposable-worker deadline with a distinct structured
  diagnostic while retaining the algorithm-level two-second diff budget.
 - Added bounded local directory manifests with collision-safe relative paths,
  two-file SHA-256 concurrency, progress, cancellation and portable comparison.
 - Added bounded line-oriented three-way merge with non-overlap combination,
  explicit ours/base/theirs conflicts and a machine-readable merge report.
 - Retained loss-aware semantic JSON, CSV/TSV and hardened XML comparisons beside
  the new directory and merge workspaces.
 ## 0.1.0 - 2026-09-01
 - Added line, word, code-point and grapheme text comparison with exact newline state and unified patch export.
@@ -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 +198,688 @@ Declared licence: Apache-2.0
 ==============================================================================
-@add-ideas/toolbox-shell-react@0.2.3
+@add-ideas/toolbox-helpers@0.2.0
 Declared licence: GPL-3.0-or-later
 ==============================================================================
 --- LICENSE ---
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 ==============================================================================
@add-ideas/toolbox-shell-react@0.3.0
 Declared licence: Apache-2.0
 ==============================================================================
 --- LICENSE ---
@@ -2,23 +2,25 @@
 Compare text and structured data locally in the browser.
-Diff Tools is a standalone, local-first application in the [add·ideas Toolbox](https://git.add-ideas.de/lotobo/toolbox-portal). Inputs are processed in a disposable browser worker and are never uploaded by the application.
+Diff Tools is a standalone, local-first application in the [add·ideas Toolbox](https://git.add-ideas.de/lotobo/toolbox-portal). Inputs are processed through the shared cancellable disposable-worker protocol, with an algorithm budget and a 15-second hard worker deadline, and are never uploaded by the application.
-## Version 0.1 scope
+## Version 0.2 scope
 - Text diff by line, word, Unicode code point or grapheme cluster, with exact LF, CRLF, CR and final-newline state.
 - Explicit text comparison rules for case, whitespace, line endings, final newline and Unicode normalization. Normalized differences stay visible.
 - Semantic JSON comparison with duplicate-key rejection, exact decimal numbers, object-order reporting and RFC 6902 output when representable.
 - Namespace-aware XML comparison with visible prefix, attribute-order, comment, whitespace and CDATA normalization. DOCTYPE, entity declarations and XInclude are rejected.
 - CSV and TSV comparison by one or more unique key columns, including duplicate-key diagnostics, string-preserving fields and visible column/row order changes.
 - Build deterministic relative-path directory manifests with local SHA-256 hashing, bounded two-file concurrency and conservative collision checks; export/import manifests and compare them without retaining file contents.
 - Perform a bounded, line-preserving three-way text merge from base/ours/theirs, with non-overlapping edits combined and explicit ours/base/theirs markers plus a JSON report for every conflict.
 - Unified and side-by-side views, an exact unified text patch and a portable, versioned JSON report.
 - Stable-last-result interaction: invalid or unfinished input does not blank the previous successful result.
-This version intentionally does not compare images, binary documents, directories or archives.
+This version does not interpret images, binary documents or archives. Directory comparison is content-digest based and cannot represent empty directories because browser directory selection exposes files only. Three-way merge is textual rather than a semantic JSON/XML merge.
 ## Safety limits
-Each input is limited to 8 MiB and 4 million characters. Parsing and output also have explicit row, cell, token, node, nesting, edit-count, time and display limits. Imported values are rendered as React text nodes; parser-provided HTML is never inserted. See [privacy and security](docs/PRIVACY-SECURITY.md).
+Each ordinary or merge input is limited to 8 MiB and 4 million characters. Directory manifests are limited to 5,000 files, 512 MiB total, 256 MiB per file, 4,096-character relative paths and two concurrent hashes. Parsing and output also have explicit row, cell, token, node, nesting, edit-count, conflict-count, time and display limits. Imported values are rendered as React text nodes; parser-provided HTML is never inserted. See [privacy and security](docs/PRIVACY-SECURITY.md).
 ## Development
@@ -38,7 +40,7 @@ The browser suite builds and serves the app below `/deep/nested/diff/`, blocks e
 npm run release:artifact
 ```
-This creates deterministic `release/diff-tools-0.1.0.zip` and `.sha256` files after all validation gates pass.
+This creates deterministic `release/diff-tools-0.2.0.zip` and `.sha256` files after all validation gates pass.
 ## Licence
@@ -1,7 +1,7 @@
 # Corresponding source
-The corresponding source for Diff Tools 0.1.0 is available at:
+The corresponding source for Diff Tools 0.2.0 is available at:
-https://git.add-ideas.de/lotobo/diff-tools/src/tag/v0.1.0
+https://git.add-ideas.de/lotobo/diff-tools/src/tag/v0.2.0
 Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.
@@ -2,14 +2,15 @@
 Diff Tools is GPL-3.0-or-later. Its direct runtime dependencies retain their own licences:
-| Package                          | Pinned version | Licence      | Purpose                                        |
+| Package                          | Pinned version | Licence          | Purpose                                        |
-| -------------------------------- | -------------: | ------------ | ---------------------------------------------- |
+| -------------------------------- | -------------: | ---------------- | ---------------------------------------------- |
-| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0   | Manifest validation                            |
+| `@add-ideas/toolbox-contract`    |          0.3.0 | Apache-2.0       | Manifest validation                            |
-| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0   | Shared Toolbox shell                           |
+| `@add-ideas/toolbox-helpers`     |          0.2.0 | GPL-3.0-or-later | Shared local-first utility primitives          |
-| `@xmldom/xmldom`                 |         0.9.12 | MIT          | Inert XML DOM parsing                          |
+| `@add-ideas/toolbox-shell-react` |          0.3.0 | Apache-2.0       | Shared Toolbox shell                           |
-| `diff`                           |          9.0.0 | BSD-3-Clause | Bounded sequence alignment and unified patches |
+| `@xmldom/xmldom`                 |         0.9.12 | MIT              | Inert XML DOM parsing                          |
-| `lossless-json`                  |          4.3.1 | MIT          | Exact-decimal JSON parsing and serialization   |
+| `diff`                           |          9.0.0 | BSD-3-Clause     | Bounded sequence alignment and unified patches |
-| `papaparse`                      |          5.7.0 | MIT          | CSV and TSV parsing                            |
+| `lossless-json`                  |          4.3.1 | MIT              | Exact-decimal JSON parsing and serialization   |
-| `react` / `react-dom`            |         19.2.8 | MIT          | User interface                                 |
+| `papaparse`                      |          5.7.0 | MIT              | CSV and TSV parsing                            |
 | `react` / `react-dom`            |         19.2.8 | MIT              | User interface                                 |
 Release artifacts include the complete licence texts collected from every locked runtime package at `LICENSES/npm-runtime-licenses.txt`.
@@ -1,6 +1,6 @@
 # Accessibility
-The workbench uses labelled native text areas, selects, checkboxes, file inputs and buttons. Comparison modes and result views are exposed as tab lists, status and diagnostic changes use live regions, and structured results use list or table semantics.
+The workbench uses labelled native text areas, selects, checkboxes, file inputs and buttons. Comparison modes and result views are exposed as labelled pressed-state button groups, status and diagnostic changes use live regions, and structured results use list or table semantics.
 Change kinds are written in text and indicated by `+`/`−` markers, not colour alone. Exact CR, LF and tab characters have visible glyphs. Focus indicators remain visible in light, dark and system themes, and controls meet a minimum 2.55 rem target height.
@@ -3,7 +3,10 @@
 Diff Tools is a static React application with a relocatable `./` build. Its comparison pipeline is deliberately separated from the view:
 1. The workbench captures strings or decodes a selected file as strict UTF-8 after a byte-size check.
-2. A fresh module worker receives a plain comparison request. Changing input cancels and terminates the preceding worker; the last successful result remains on screen until a replacement succeeds.
+2. A fresh module worker receives a typed shared worker-job request. Changing
   input cancels and terminates the preceding worker; job IDs exclude stale
   messages, and a 15-second hard deadline bounds the whole worker. The last
   successful result remains on screen until a replacement succeeds.
 3. A mode-specific pure comparator produces display rows and diagnostics. Normalized rows are first-class output, not discarded state.
 4. The orchestrator adds exact input metadata, a bounded unified patch and a schema-labelled portable report.
 5. React renders values as text. The app never consumes or inserts HTML produced by a diff or parser library.
@@ -16,7 +19,11 @@ When `Worker` is unavailable, such as in unit tests, the same pure comparator ru
 - JSON uses `lossless-json`, rejects duplicate and prototype-affecting keys, and compares numbers without converting to IEEE-754. Object member order is semantically ignored but reported.
 - XML rejects active declaration/include syntax and preflights structure before `@xmldom/xmldom` builds an inert DOM. Elements and attributes compare by expanded name when selected.
 - CSV/TSV uses Papa Parse in string mode. Unique composite keys align rows; no spreadsheet type inference is performed.
 - Directory manifests strip the one common browser-selected root, validate every relative path and conservative case/Unicode collision key, then hash file bytes with SHA-256 under count, per-file, aggregate and concurrency ceilings. The sorted, versioned JSON artifact can be compared later without the files.
 - Three-way merge independently derives bounded token edits from base to ours and base to theirs. Non-overlapping regions compose; overlapping regions are compared against each other and the base before conflict markers are emitted. It does not claim semantic structured-data merging.
-All report and patch formats are generated locally. `de.add-ideas.diff-tools.report.v1` is the portable report schema identifier.
+All report and patch formats are generated locally. `de.add-ideas.diff-tools.report.v1`, `de.add-ideas.diff-tools.directory-manifest.v1` and `de.add-ideas.diff-tools.merge-report.v1` identify the portable artifacts.
-The planned shared `@add-ideas/toolbox-helpers` package is not yet published at a compatible version, so v0.1 keeps its bounded domain functions inside `src/core`. They can be extracted without changing the worker protocol or report schema.
+Diff algorithms, semantic models and reports remain bounded domain functions in
 `src/core`. Generic byte-size display, safe Blob downloads and cancellable
 worker lifecycle come from `@add-ideas/toolbox-helpers` 0.2.0.
@@ -13,6 +13,9 @@ The production CSP permits same-origin scripts and workers and blocks objects, f
 - XML containing DOCTYPE, entity declaration or XInclude syntax is rejected before DOM parsing. A lexical preflight rejects excessive element count or nesting before DOM construction.
 - JSON rejects duplicate keys and the prototype-affecting keys `__proto__`, `prototype` and `constructor`.
 - CSV/TSV fields remain strings; formulas are displayed as text and are not evaluated.
 - Directory hashing rejects traversal, absolute/control-laden and case/Unicode-colliding relative paths. SHA-256 reads use bounded concurrency, file/count/aggregate ceilings and an abort signal.
 - Imported manifests are schema-, path-, digest-, order- and total-validated before comparison. Directory names and digests are sensitive metadata and should be reviewed before sharing.
 - Three-way inputs use the same text ceilings plus an explicit conflict cap; conflict labels have CR/LF removed before entering marker lines.
 - Imported strings are rendered through React text nodes and form controls. No library-generated HTML, imported markup or script is inserted into the document.
 These controls bound this tool's work; they are not a general-purpose sanitizer and do not make imported data safe for another application.
@@ -1,5 +1,5 @@
 const CACHE_PREFIX = "diff-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(
@@ -3,12 +3,22 @@
  "schemaVersion": 1,
  "id": "de.add-ideas.diff-tools",
  "name": "Diff Tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
-  "description": "Compare text and structured data locally in the browser.",
+  "description": "Compare files and directories or perform bounded three-way merges locally.",
  "entry": "./",
  "icon": "./favicon.svg",
  "categories": ["developer", "files", "productivity"],
-  "tags": ["diff", "compare", "json", "xml", "csv", "patch"],
+  "tags": [
    "diff",
    "compare",
    "json",
    "xml",
    "csv",
    "patch",
    "directory",
    "manifest",
    "merge"
  ],
  "integration": {
    "contextVersion": 1,
    "launchModes": ["navigate", "new-tab"],
@@ -21,6 +31,43 @@
    "crossOriginIsolated": false,
    "topLevelContext": false
  },
  "io": {
    "accepts": [
      {
        "mediaType": "text/*",
        "extensions": [".txt", ".md", ".csv", ".xml"],
        "label": "Text, CSV and XML files"
      },
      {
        "mediaType": "application/json",
        "extensions": [".json"],
        "label": "JSON documents and directory manifests"
      },
      {
        "mediaType": "*/*",
        "extensions": [],
        "label": "Files selected for bounded directory hashing"
      }
    ],
    "produces": [
      {
        "mediaType": "text/x-diff",
        "extensions": [".diff", ".patch"],
        "label": "Unified and JSON patches"
      },
      {
        "mediaType": "text/plain",
        "extensions": [".txt"],
        "label": "Three-way merge result"
      },
      {
        "mediaType": "application/json",
        "extensions": [".json"],
        "label": "Diff, merge and directory-manifest reports"
      }
    ]
  },
  "capabilities": { "required": ["workers"], "optional": ["web-crypto"] },
  "privacy": {
    "processing": "local",
    "fileUploads": true,
@@ -0,0 +1,278 @@
 import { formatBytes, triggerBlobDownload } from "@add-ideas/toolbox-helpers";
 import { useMemo, useRef, useState, type ChangeEvent } from "react";
 import {
  compareDirectoryManifests,
  createDirectoryManifest,
  parseDirectoryManifest,
  serializeDirectoryManifest,
  type DirectoryManifest,
 } from "../core/directory-manifest";
 type Side = "left" | "right";
 const directoryAttributes = {
  webkitdirectory: "",
  directory: "",
 } as Record<string, string>;
 export function DirectoryWorkspace() {
  const [files, setFiles] = useState<Record<Side, File[]>>({
    left: [],
    right: [],
  });
  const [manifests, setManifests] = useState<
    Partial<Record<Side, DirectoryManifest>>
  >({});
  const [status, setStatus] = useState(
    "Choose two directories or import saved manifests.",
  );
  const [error, setError] = useState("");
  const [busy, setBusy] = useState(false);
  const [changesOnly, setChangesOnly] = useState(true);
  const controller = useRef<AbortController | undefined>(undefined);
  const changes = useMemo(() => {
    if (!manifests.left || !manifests.right) return [];
    return compareDirectoryManifests(manifests.left, manifests.right);
  }, [manifests]);
  const visible = changes.filter(
    (change) => !changesOnly || change.status !== "same",
  );
  async function build(): Promise<void> {
    if (
      (!files.left.length && !manifests.left) ||
      (!files.right.length && !manifests.right)
    )
      return;
    controller.current?.abort();
    const next = new AbortController();
    controller.current = next;
    setBusy(true);
    setError("");
    try {
      const left =
        manifests.left ??
        (await createDirectoryManifest(files.left, {
          signal: next.signal,
          onProgress: (progress) =>
            setStatus(
              `Hashing left: ${progress.completed} / ${progress.total} · ${progress.path}`,
            ),
        }));
      const right =
        manifests.right ??
        (await createDirectoryManifest(files.right, {
          signal: next.signal,
          onProgress: (progress) =>
            setStatus(
              `Hashing right: ${progress.completed} / ${progress.total} · ${progress.path}`,
            ),
        }));
      if (next.signal.aborted) return;
      setManifests({ left, right });
      const result = compareDirectoryManifests(left, right);
      setStatus(
        `Compared ${result.length.toLocaleString()} relative paths; ${result.filter((item) => item.status !== "same").length.toLocaleString()} changed.`,
      );
    } catch (reason) {
      if (!next.signal.aborted)
        setError(
          reason instanceof Error
            ? reason.message
            : "Directory comparison failed.",
        );
    } finally {
      if (controller.current === next) setBusy(false);
    }
  }
  async function importManifest(
    side: Side,
    event: ChangeEvent<HTMLInputElement>,
  ) {
    const file = event.currentTarget.files?.[0];
    event.currentTarget.value = "";
    if (!file) return;
    try {
      const manifest = parseDirectoryManifest(await file.text());
      setManifests((current) => ({ ...current, [side]: manifest }));
      setFiles((current) => ({ ...current, [side]: [] }));
      setError("");
      setStatus(
        `Imported ${side} manifest with ${manifest.entries.length.toLocaleString()} files.`,
      );
    } catch (reason) {
      setError(
        reason instanceof Error
          ? reason.message
          : "Invalid directory manifest.",
      );
    }
  }
  function selectedDirectory(side: Side, event: ChangeEvent<HTMLInputElement>) {
    const selected = [...(event.currentTarget.files ?? [])];
    event.currentTarget.value = "";
    setFiles((current) => ({ ...current, [side]: selected }));
    setManifests((current) => ({ ...current, [side]: undefined }));
    setStatus(`Selected ${selected.length.toLocaleString()} ${side} files.`);
  }
  function downloadManifest(side: Side): void {
    const manifest = manifests[side];
    if (!manifest) return;
    triggerBlobDownload(
      new Blob([serializeDirectoryManifest(manifest)], {
        type: "application/json;charset=utf-8",
      }),
      `${side}-directory-manifest.json`,
    );
  }
  function cancelBuild(): void {
    controller.current?.abort();
    setStatus(
      "Directory hashing cancelled. Existing manifests were left unchanged.",
    );
  }
  return (
    <section
      className="panel directory-workspace"
      aria-labelledby="directory-title"
    >
      <div className="panel-heading">
        <div>
          <p className="eyebrow">Relative paths · SHA-256</p>
          <h2 id="directory-title">Directory manifests</h2>
        </div>
        {busy ? (
          <button type="button" onClick={cancelBuild}>
            Cancel
          </button>
        ) : null}
      </div>
      <p className="option-note">
        File contents are hashed locally with bounded two-file concurrency.
        Empty directories are not exposed by browser file selection and
        therefore cannot appear in a manifest.
      </p>
      <div className="directory-inputs">
        {(["left", "right"] as const).map((side) => (
          <article key={side}>
            <h3>{side === "left" ? "Before directory" : "After directory"}</h3>
            <div className="button-row">
              <label className="button file-button">
                Choose directory
                <input
                  type="file"
                  multiple
                  {...directoryAttributes}
                  onChange={(event) => selectedDirectory(side, event)}
                  data-testid={`${side}-directory-input`}
                />
              </label>
              <label className="button file-button">
                Import manifest
                <input
                  type="file"
                  accept=".json,application/json"
                  onChange={(event) => void importManifest(side, event)}
                />
              </label>
              <button
                type="button"
                disabled={!manifests[side]}
                onClick={() => downloadManifest(side)}
              >
                Download manifest
              </button>
            </div>
            <p>
              {manifests[side]
                ? `${manifests[side]!.entries.length.toLocaleString()} manifested files · ${formatBytes(manifests[side]!.totals.bytes)}`
                : `${files[side].length.toLocaleString()} selected files`}
            </p>
          </article>
        ))}
      </div>
      <div className="compare-bar">
        <button
          type="button"
          className="primary-button"
          disabled={
            busy ||
            (!files.left.length && !manifests.left) ||
            (!files.right.length && !manifests.right)
          }
          onClick={() => void build()}
        >
          Build & compare manifests
        </button>
        <p role="status" aria-live="polite">
          {status}
        </p>
      </div>
      {error ? (
        <p className="diagnostic diagnostic--error" role="alert">
          {error}
        </p>
      ) : null}
      {changes.length ? (
        <>
          <label className="toggle manifest-filter">
            <input
              type="checkbox"
              checked={changesOnly}
              onChange={(event) => setChangesOnly(event.target.checked)}
            />
            <span>
              <strong>Show changes only</strong>
            </span>
          </label>
          <div
            className="table-scroll"
            tabIndex={0}
            role="region"
            aria-label="Directory manifest comparison"
          >
            <table>
              <thead>
                <tr>
                  <th>Path</th>
                  <th>Status</th>
                  <th>Before</th>
                  <th>After</th>
                  <th>Meaning</th>
                </tr>
              </thead>
              <tbody>
                {visible.map((change) => (
                  <tr key={change.path}>
                    <th scope="row">
                      <code>{change.path}</code>
                    </th>
                    <td>
                      <span
                        className={`kind-badge kind-badge--${change.status}`}
                      >
                        {change.status}
                      </span>
                    </td>
                    <td>
                      {change.left ? formatBytes(change.left.bytes) : "—"}
                    </td>
                    <td>
                      {change.right ? formatBytes(change.right.bytes) : "—"}
                    </td>
                    <td>{change.detail}</td>
                  </tr>
                ))}
              </tbody>
            </table>
          </div>
        </>
      ) : null}
    </section>
  );
 }
@@ -32,7 +32,9 @@ export function HelpDialog({
        </button>
      </div>
      <p>
-        Compare exact text or the structure of JSON, XML, CSV and TSV locally.
+        Compare exact text or the structure of JSON, XML, CSV and TSV locally,
        compare bounded directory manifests, or merge two variants against an
        explicit base.
      </p>
      <ul>
        <li>Text keeps CRLF, LF, CR and final-newline state exact.</li>
@@ -41,6 +43,14 @@ export function HelpDialog({
        <li>
          CSV rows are matched by unique key columns and fields remain strings.
        </li>
        <li>
          Directory comparison hashes selected files locally with SHA-256; empty
          directories cannot be observed through browser file selection.
        </li>
        <li>
          Three-way merge combines non-overlapping line edits and emits
          ours/base/theirs markers plus a report for overlaps.
        </li>
      </ul>
      <p>
        Ignored and normalized differences remain visible. All processing is
@@ -0,0 +1,123 @@
 import { triggerBlobDownload } from "@add-ideas/toolbox-helpers";
 import { useState } from "react";
 import { mergeThreeWay, type MergeResult } from "../core/merge";
 const SAMPLE = {
  base: "title\nshared\nfooter\n",
  ours: "title from ours\nshared\nfooter\n",
  theirs: "title\nshared\nfooter from theirs\n",
 };
 export function MergeWorkspace() {
  const [base, setBase] = useState(SAMPLE.base);
  const [ours, setOurs] = useState(SAMPLE.ours);
  const [theirs, setTheirs] = useState(SAMPLE.theirs);
  const [error, setError] = useState("");
  const [result, setResult] = useState<MergeResult>();
  function merge(): void {
    try {
      setResult(mergeThreeWay({ base, ours, theirs }));
      setError("");
    } catch (reason) {
      setError(
        reason instanceof Error ? reason.message : "Three-way merge failed.",
      );
      setResult(undefined);
    }
  }
  function download(text: string, name: string, type: string): void {
    triggerBlobDownload(new Blob([text], { type }), name);
  }
  return (
    <section className="panel merge-workspace" aria-labelledby="merge-title">
      <div className="panel-heading">
        <div>
          <p className="eyebrow">Bounded line merge</p>
          <h2 id="merge-title">Three-way merge</h2>
        </div>
      </div>
      <p className="option-note">
        Changes are derived independently from the base. Non-overlapping edits
        merge automatically; overlapping results get explicit ours/base/theirs
        conflict markers. This is text merge, not a semantic JSON/XML merge.
      </p>
      <div className="merge-inputs">
        {(
          [
            ["Base", base, setBase],
            ["Ours", ours, setOurs],
            ["Theirs", theirs, setTheirs],
          ] as const
        ).map(([label, value, setter]) => (
          <label className="field" key={label}>
            <span>{label}</span>
            <textarea
              value={value}
              onChange={(event) => setter(event.target.value)}
              spellCheck={false}
            />
          </label>
        ))}
      </div>
      <button type="button" className="primary-button" onClick={merge}>
        Merge locally
      </button>
      {error ? (
        <p className="diagnostic diagnostic--error" role="alert">
          {error}
        </p>
      ) : null}
      {result ? (
        <div className="merge-result">
          <div className="artifact-heading">
            <div>
              <p className="eyebrow">
                {result.clean ? "Clean merge" : "Review required"}
              </p>
              <h3>{result.conflicts.length} conflict(s)</h3>
            </div>
            <div>
              <button
                type="button"
                onClick={() =>
                  download(
                    result.report,
                    "merge-report.json",
                    "application/json",
                  )
                }
              >
                Download report
              </button>
              <button
                type="button"
                className="primary-button"
                onClick={() =>
                  download(
                    result.text,
                    "merged.txt",
                    "text/plain;charset=utf-8",
                  )
                }
              >
                Download merged text
              </button>
            </div>
          </div>
          <label className="field output-field">
            <span>Merged text</span>
            <textarea
              readOnly
              value={result.text}
              data-testid="merge-output"
              spellCheck={false}
            />
          </label>
        </div>
      ) : null}
    </section>
  );
 }
@@ -1,3 +1,4 @@
 import { formatBytes, triggerBlobDownload } from "@add-ideas/toolbox-helpers";
 import {
  useCallback,
  useEffect,
@@ -8,6 +9,8 @@ import {
 } from "react";
 import { DIFF_LIMITS } from "../core/limits";
 import { createCompareTask, type CompareTask } from "../core/worker-client";
 import { DirectoryWorkspace } from "./DirectoryWorkspace";
 import { MergeWorkspace } from "./MergeWorkspace";
 import {
  DEFAULT_OPTIONS,
  DiffToolsError,
@@ -90,11 +93,7 @@ function visibleText(value: string | undefined): string {
 }
 function bytes(value: number): string {
-  return value < 1_024
+  return formatBytes(value, { fractionDigits: value < 1_024 ? 0 : 1 });
    ? `${value} B`
    : value < 1_048_576
      ? `${(value / 1_024).toFixed(1)} KiB`
      : `${(value / 1_048_576).toFixed(1)} MiB`;
 }
 function fileExtension(mode: DiffMode, artifact: "report" | "patch"): string {
@@ -103,20 +102,10 @@ function fileExtension(mode: DiffMode, artifact: "report" | "patch"): string {
 }
 function download(value: string, name: string): void {
-  const blob = new Blob([value], { type: "text/plain;charset=utf-8" });
+  triggerBlobDownload(
-  const url = URL.createObjectURL(blob);
+    new Blob([value], { type: "text/plain;charset=utf-8" }),
-  const anchor = document.createElement("a");
+    name,
-  anchor.href = url;
+  );
  anchor.download = name;
  anchor.hidden = true;
  anchor.rel = "noopener";
  document.body.append(anchor);
  try {
    anchor.click();
  } finally {
    anchor.remove();
    queueMicrotask(() => URL.revokeObjectURL(url));
  }
 }
 function Toggle({
@@ -516,6 +505,9 @@ export function Workbench() {
  );
  const [statusText, setStatusText] = useState("Ready to compare locally.");
  const [notice, setNotice] = useState("");
  const [workspace, setWorkspace] = useState<
    "compare" | "directories" | "merge"
  >("compare");
  const task = useRef<CompareTask | undefined>(undefined);
  const sequence = useRef(0);
  const input = inputs[mode];
@@ -680,320 +672,356 @@ export function Workbench() {
        <span className="privacy-pill">Browser-local</span>
      </header>
-      <nav className="mode-tabs" aria-label="Comparison modes">
+      <nav className="workspace-tabs" aria-label="Diff workspaces">
-        <div role="tablist" aria-label="Comparison modes">
+        {(
-          {MODES.map((item) => (
+          [
-            <button
+            ["compare", "Two-way compare"],
-              key={item.id}
+            ["directories", "Directories"],
-              type="button"
+            ["merge", "Three-way merge"],
-              role="tab"
+          ] as const
-              aria-label={`${item.label} ${item.hint}`}
+        ).map(([id, label]) => (
-              aria-selected={mode === item.id}
+          <button
-              onClick={() => setRoute(item.id, view)}
+            key={id}
-            >
+            type="button"
-              <span>{item.label}</span>
+            aria-current={workspace === id ? "page" : undefined}
-              <small>{item.hint}</small>
+            onClick={() => setWorkspace(id)}
-            </button>
+          >
-          ))}
+            {label}
-        </div>
+          </button>
        ))}
      </nav>
-      <section className="panel options-panel" aria-labelledby="options-title">
+      {workspace === "compare" ? (
-        <div className="panel-heading">
+        <>
-          <div>
+          <nav className="mode-tabs" aria-label="Comparison modes">
-            <p className="eyebrow">Visible semantics</p>
+            <div role="group" aria-label="Comparison modes">
-            <h2 id="options-title">Comparison options</h2>
+              {MODES.map((item) => (
          </div>
        </div>
        <Options mode={mode} options={options} setOptions={setOptions} />
      </section>
      <section className="input-grid" aria-label="Comparison inputs">
        {(["left", "right"] as const).map((side) => (
          <article className="panel input-panel" key={side}>
            <div className="panel-heading">
              <div>
                <p className="eyebrow">
                  {side === "left" ? "Before" : "After"}
                </p>
                <h2>
                  {input[`${side}Name`] ??
                    (side === "left" ? "Original" : "Changed")}
                </h2>
              </div>
              <label className="button file-button">
                Open file
                <input
                  type="file"
                  onChange={(event) => fileChanged(side, event)}
                  data-testid={`${side}-file-input`}
                />
              </label>
            </div>
            <label className="field">
              <span>{side === "left" ? "Before text" : "After text"}</span>
              <textarea
                value={input[side]}
                onChange={(event) => updateInput(side, event.target.value)}
                spellCheck={false}
                data-testid={`${side}-editor`}
              />
            </label>
          </article>
        ))}
      </section>
      <div className="compare-bar panel">
        <button
          type="button"
          onClick={() =>
            setInputs((current) => ({
              ...current,
              [mode]: {
                left: current[mode].right,
                right: current[mode].left,
                leftName: current[mode].rightName,
                rightName: current[mode].leftName,
              },
            }))
          }
        >
          Swap sides
        </button>
        <button
          type="button"
          className="primary-button"
          onClick={() => compare(request)}
        >
          Compare now
        </button>
        <p role="status" aria-live="polite" data-status={status}>
          {statusText}
        </p>
      </div>
      <Diagnostics diagnostics={diagnostics} />
      {result ? (
        <section className="results" aria-label="Comparison result">
          <div className="summary-grid">
            <article className="summary-card summary-card--verdict">
              <span>Verdict</span>
              <strong>
                {result.exactlyEqual
                  ? "Exactly equal"
                  : result.semanticallyEqual
                    ? "Semantically equal"
                    : "Different"}
              </strong>
              <small>
                {result.exactlyEqual
                  ? "Source text matches"
                  : "Exact source differs"}
              </small>
            </article>
            {(["added", "removed", "modified", "normalized"] as const).map(
              (kind) => (
                <article
                  className={`summary-card summary-card--${kind}`}
                  key={kind}
                >
                  <span>{kind}</span>
                  <strong>{result.stats[kind]}</strong>
                  <small>
                    display row{result.stats[kind] === 1 ? "" : "s"}
                  </small>
                </article>
              ),
            )}
          </div>
          <section className="metadata panel" aria-labelledby="metadata-title">
            <div className="panel-heading">
              <div>
                <p className="eyebrow">Exact source state</p>
                <h2 id="metadata-title">Newlines and size</h2>
              </div>
            </div>
            <div className="metadata-grid">
              {[result.left, result.right].map((item, index) => (
                <dl key={index}>
                  <div>
                    <dt>Side</dt>
                    <dd>{index === 0 ? "Before" : "After"}</dd>
                  </div>
                  <div>
                    <dt>Size</dt>
                    <dd>{bytes(item.bytes)}</dd>
                  </div>
                  <div>
                    <dt>Lines</dt>
                    <dd>{item.lines}</dd>
                  </div>
                  <div>
                    <dt>LF</dt>
                    <dd>{item.newlines.lf}</dd>
                  </div>
                  <div>
                    <dt>CRLF</dt>
                    <dd>{item.newlines.crlf}</dd>
                  </div>
                  <div>
                    <dt>CR</dt>
                    <dd>{item.newlines.cr}</dd>
                  </div>
                  <div>
                    <dt>Final newline</dt>
                    <dd>{item.newlines.final}</dd>
                  </div>
                </dl>
              ))}
            </div>
            <div className="normalization-list">
              <strong>Applied comparison rules</strong>
              {result.appliedNormalizations.length ? (
                result.appliedNormalizations.map((item) => (
                  <span key={item}>{item}</span>
                ))
              ) : (
                <span>Exact source comparison</span>
              )}
            </div>
          </section>
          <nav className="result-tabs" aria-label="Result views">
            <div role="tablist" aria-label="Result views">
              {RESULT_VIEWS.map((item) => (
                <button
                  type="button"
                  role="tab"
                  aria-selected={view === item.id}
                  key={item.id}
-                  onClick={() => setRoute(mode, item.id)}
+                  type="button"
                  aria-label={`${item.label} ${item.hint}`}
                  aria-pressed={mode === item.id}
                  onClick={() => setRoute(item.id, view)}
                >
-                  {item.label}
+                  <span>{item.label}</span>
                  <small>{item.hint}</small>
                </button>
              ))}
            </div>
          </nav>
-          <section className="panel result-panel" role="tabpanel">
+          <section
-            {view === "unified" ? <UnifiedRows rows={result.rows} /> : null}
+            className="panel options-panel"
-            {view === "side-by-side" ? (
+            aria-labelledby="options-title"
-              <SideBySideRows rows={result.rows} />
+          >
-            ) : null}
+            <div className="panel-heading">
-            {view === "report" ? (
+              <div>
-              <div className="artifact">
+                <p className="eyebrow">Visible semantics</p>
-                <div className="artifact-heading">
+                <h2 id="options-title">Comparison options</h2>
              </div>
            </div>
            <Options mode={mode} options={options} setOptions={setOptions} />
          </section>
          <section className="input-grid" aria-label="Comparison inputs">
            {(["left", "right"] as const).map((side) => (
              <article className="panel input-panel" key={side}>
                <div className="panel-heading">
                  <div>
-                    <p className="eyebrow">Portable artifact</p>
+                    <p className="eyebrow">
-                    <h2>JSON report</h2>
+                      {side === "left" ? "Before" : "After"}
                    </p>
                    <h2>
                      {input[`${side}Name`] ??
                        (side === "left" ? "Original" : "Changed")}
                    </h2>
                  </div>
                  <label className="button file-button">
                    Open file
                    <input
                      type="file"
                      onChange={(event) => fileChanged(side, event)}
                      data-testid={`${side}-file-input`}
                    />
                  </label>
                </div>
                <label className="field">
                  <span>{side === "left" ? "Before text" : "After text"}</span>
                  <textarea
                    value={input[side]}
                    onChange={(event) => updateInput(side, event.target.value)}
                    spellCheck={false}
                    data-testid={`${side}-editor`}
                  />
                </label>
              </article>
            ))}
          </section>
          <div className="compare-bar panel">
            <button
              type="button"
              onClick={() =>
                setInputs((current) => ({
                  ...current,
                  [mode]: {
                    left: current[mode].right,
                    right: current[mode].left,
                    leftName: current[mode].rightName,
                    rightName: current[mode].leftName,
                  },
                }))
              }
            >
              Swap sides
            </button>
            <button
              type="button"
              className="primary-button"
              onClick={() => compare(request)}
            >
              Compare now
            </button>
            <p role="status" aria-live="polite" data-status={status}>
              {statusText}
            </p>
          </div>
          <Diagnostics diagnostics={diagnostics} />
          {result ? (
            <section className="results" aria-label="Comparison result">
              <div className="summary-grid">
                <article className="summary-card summary-card--verdict">
                  <span>Verdict</span>
                  <strong>
                    {result.exactlyEqual
                      ? "Exactly equal"
                      : result.semanticallyEqual
                        ? "Semantically equal"
                        : "Different"}
                  </strong>
                  <small>
                    {result.exactlyEqual
                      ? "Source text matches"
                      : "Exact source differs"}
                  </small>
                </article>
                {(["added", "removed", "modified", "normalized"] as const).map(
                  (kind) => (
                    <article
                      className={`summary-card summary-card--${kind}`}
                      key={kind}
                    >
                      <span>{kind}</span>
                      <strong>{result.stats[kind]}</strong>
                      <small>
                        display row{result.stats[kind] === 1 ? "" : "s"}
                      </small>
                    </article>
                  ),
                )}
              </div>
              <section
                className="metadata panel"
                aria-labelledby="metadata-title"
              >
                <div className="panel-heading">
                  <div>
-                    <button
+                    <p className="eyebrow">Exact source state</p>
-                      type="button"
+                    <h2 id="metadata-title">Newlines and size</h2>
                      onClick={() => void copy(result.report, "JSON report")}
                    >
                      Copy
                    </button>
                    <button
                      type="button"
                      className="primary-button"
                      onClick={() =>
                        download(
                          result.report,
                          `diff-report.${fileExtension(mode, "report")}`,
                        )
                      }
                    >
                      Download
                    </button>
                  </div>
                </div>
-                <textarea
+                <div className="metadata-grid">
-                  readOnly
+                  {[result.left, result.right].map((item, index) => (
-                  value={result.report}
+                    <dl key={index}>
-                  data-testid="json-report"
+                      <div>
-                />
+                        <dt>Side</dt>
-              </div>
+                        <dd>{index === 0 ? "Before" : "After"}</dd>
-            ) : null}
+                      </div>
-            {view === "patch" ? (
+                      <div>
-              <div className="patch-grid">
+                        <dt>Size</dt>
-                <div className="artifact">
+                        <dd>{bytes(item.bytes)}</dd>
-                  <div className="artifact-heading">
+                      </div>
-                    <div>
+                      <div>
-                      <p className="eyebrow">Exact source transform</p>
+                        <dt>Lines</dt>
-                      <h2>Unified patch</h2>
+                        <dd>{item.lines}</dd>
-                    </div>
+                      </div>
-                    <div>
+                      <div>
-                      <button
+                        <dt>LF</dt>
-                        type="button"
+                        <dd>{item.newlines.lf}</dd>
-                        onClick={() =>
+                      </div>
-                          void copy(result.unifiedPatch, "Unified patch")
+                      <div>
-                        }
+                        <dt>CRLF</dt>
-                        disabled={!result.unifiedPatch}
+                        <dd>{item.newlines.crlf}</dd>
-                      >
+                      </div>
-                        Copy
+                      <div>
-                      </button>
+                        <dt>CR</dt>
-                      <button
+                        <dd>{item.newlines.cr}</dd>
-                        type="button"
+                      </div>
-                        className="primary-button"
+                      <div>
-                        disabled={!result.unifiedPatch}
+                        <dt>Final newline</dt>
-                        onClick={() =>
+                        <dd>{item.newlines.final}</dd>
-                          result.unifiedPatch &&
+                      </div>
-                          download(
+                    </dl>
-                            result.unifiedPatch,
+                  ))}
-                            `changes.${fileExtension(mode, "patch")}`,
+                </div>
-                          )
+                <div className="normalization-list">
-                        }
+                  <strong>Applied comparison rules</strong>
-                      >
+                  {result.appliedNormalizations.length ? (
-                        Download
+                    result.appliedNormalizations.map((item) => (
-                      </button>
+                      <span key={item}>{item}</span>
-                    </div>
+                    ))
                  </div>
                  {result.unifiedPatch ? (
                    <textarea
                      readOnly
                      value={result.unifiedPatch}
                      data-testid="unified-patch"
                    />
                  ) : (
-                    <p className="empty-result">
+                    <span>Exact source comparison</span>
                      Patch unavailable at the configured safety limit.
                    </p>
                  )}
                </div>
-                {mode === "json" ? (
+              </section>
              <nav className="result-tabs" aria-label="Result views">
                <div role="group" aria-label="Result views">
                  {RESULT_VIEWS.map((item) => (
                    <button
                      type="button"
                      aria-pressed={view === item.id}
                      key={item.id}
                      onClick={() => setRoute(mode, item.id)}
                    >
                      {item.label}
                    </button>
                  ))}
                </div>
              </nav>
              <section className="panel result-panel">
                {view === "unified" ? <UnifiedRows rows={result.rows} /> : null}
                {view === "side-by-side" ? (
                  <SideBySideRows rows={result.rows} />
                ) : null}
                {view === "report" ? (
                  <div className="artifact">
                    <div className="artifact-heading">
                      <div>
-                        <p className="eyebrow">Semantic transform</p>
+                        <p className="eyebrow">Portable artifact</p>
-                        <h2>RFC 6902 JSON Patch</h2>
+                        <h2>JSON report</h2>
                      </div>
                      <div>
                        <button
                          type="button"
                          onClick={() =>
                            void copy(result.report, "JSON report")
                          }
                        >
                          Copy
                        </button>
                        <button
                          type="button"
                          className="primary-button"
                          onClick={() =>
                            download(
                              result.report,
                              `diff-report.${fileExtension(mode, "report")}`,
                            )
                          }
                        >
                          Download
                        </button>
                      </div>
                      <button
                        type="button"
                        onClick={() =>
                          void copy(result.jsonPatch, "JSON Patch")
                        }
                      >
                        Copy
                      </button>
                    </div>
                    <textarea
                      readOnly
-                      value={result.jsonPatch ?? ""}
+                      aria-label="JSON comparison report"
-                      data-testid="json-patch"
+                      value={result.report}
                      data-testid="json-report"
                    />
                  </div>
                ) : null}
-              </div>
+                {view === "patch" ? (
-            ) : null}
+                  <div className="patch-grid">
-          </section>
+                    <div className="artifact">
-        </section>
+                      <div className="artifact-heading">
-      ) : null}
+                        <div>
-      <p className="action-notice" role="status" aria-live="polite">
+                          <p className="eyebrow">Exact source transform</p>
-        {notice}
+                          <h2>Unified patch</h2>
-      </p>
+                        </div>
                        <div>
                          <button
                            type="button"
                            onClick={() =>
                              void copy(result.unifiedPatch, "Unified patch")
                            }
                            disabled={!result.unifiedPatch}
                          >
                            Copy
                          </button>
                          <button
                            type="button"
                            className="primary-button"
                            disabled={!result.unifiedPatch}
                            onClick={() =>
                              result.unifiedPatch &&
                              download(
                                result.unifiedPatch,
                                `changes.${fileExtension(mode, "patch")}`,
                              )
                            }
                          >
                            Download
                          </button>
                        </div>
                      </div>
                      {result.unifiedPatch ? (
                        <textarea
                          readOnly
                          aria-label="Unified patch"
                          value={result.unifiedPatch}
                          data-testid="unified-patch"
                        />
                      ) : (
                        <p className="empty-result">
                          Patch unavailable at the configured safety limit.
                        </p>
                      )}
                    </div>
                    {mode === "json" ? (
                      <div className="artifact">
                        <div className="artifact-heading">
                          <div>
                            <p className="eyebrow">Semantic transform</p>
                            <h2>RFC 6902 JSON Patch</h2>
                          </div>
                          <button
                            type="button"
                            onClick={() =>
                              void copy(result.jsonPatch, "JSON Patch")
                            }
                          >
                            Copy
                          </button>
                        </div>
                        <textarea
                          readOnly
                          aria-label="RFC 6902 JSON Patch"
                          value={result.jsonPatch ?? ""}
                          data-testid="json-patch"
                        />
                      </div>
                    ) : null}
                  </div>
                ) : null}
              </section>
            </section>
          ) : null}
          <p className="action-notice" role="status" aria-live="polite">
            {notice}
          </p>
        </>
      ) : workspace === "directories" ? (
        <DirectoryWorkspace />
      ) : (
        <MergeWorkspace />
      )}
    </main>
  );
 }
@@ -0,0 +1,331 @@
 import { DIFF_LIMITS } from "./limits";
 export interface DirectoryManifestEntry {
  readonly path: string;
  readonly bytes: number;
  readonly sha256: string;
  readonly lastModified?: string;
 }
 export interface DirectoryManifest {
  readonly schema: "de.add-ideas.diff-tools.directory-manifest.v1";
  readonly schemaVersion: 1;
  readonly generatedLocally: true;
  readonly rootLabel?: string;
  readonly hashAlgorithm: "SHA-256";
  readonly entries: readonly DirectoryManifestEntry[];
  readonly totals: { readonly files: number; readonly bytes: number };
 }
 export interface ManifestProgress {
  readonly completed: number;
  readonly total: number;
  readonly path: string;
 }
 export interface ManifestChange {
  readonly path: string;
  readonly status: "same" | "added" | "removed" | "modified";
  readonly left?: DirectoryManifestEntry;
  readonly right?: DirectoryManifestEntry;
  readonly detail: string;
 }
 export async function createDirectoryManifest(
  files: readonly File[],
  options: {
    readonly signal?: AbortSignal;
    readonly onProgress?: (progress: ManifestProgress) => void;
    readonly concurrency?: number;
  } = {},
 ): Promise<DirectoryManifest> {
  if (!globalThis.crypto?.subtle)
    throw new Error("The browser Web Crypto digest API is unavailable.");
  if (files.length > DIFF_LIMITS.maxDirectoryFiles)
    throw new RangeError(
      `Directory contains more than ${DIFF_LIMITS.maxDirectoryFiles.toLocaleString()} files.`,
    );
  const paths = relativePaths(files);
  let totalBytes = 0;
  const collisionKeys = new Set<string>();
  for (const [index, file] of files.entries()) {
    throwIfAborted(options.signal);
    if (file.size > DIFF_LIMITS.maxDirectoryFileBytes)
      throw new RangeError(
        `${paths[index]} exceeds the per-file hashing limit.`,
      );
    totalBytes += file.size;
    if (
      !Number.isSafeInteger(totalBytes) ||
      totalBytes > DIFF_LIMITS.maxDirectoryBytes
    )
      throw new RangeError(
        "Directory files exceed the aggregate hashing limit.",
      );
    const key = paths[index]!.normalize("NFC").toLocaleLowerCase("en-US");
    if (collisionKeys.has(key))
      throw new Error(
        `Directory path collision after conservative normalization: ${paths[index]}.`,
      );
    collisionKeys.add(key);
  }
  const entries: DirectoryManifestEntry[] = new Array(files.length);
  let next = 0;
  let completed = 0;
  const concurrency = Math.max(
    1,
    Math.min(
      DIFF_LIMITS.directoryHashConcurrency,
      Math.floor(options.concurrency ?? DIFF_LIMITS.directoryHashConcurrency),
    ),
  );
  const worker = async () => {
    while (true) {
      const index = next++;
      if (index >= files.length) return;
      const file = files[index]!;
      const path = paths[index]!;
      throwIfAborted(options.signal);
      const digest = await crypto.subtle.digest(
        "SHA-256",
        await file.arrayBuffer(),
      );
      throwIfAborted(options.signal);
      entries[index] = {
        path,
        bytes: file.size,
        sha256: hex(new Uint8Array(digest)),
        lastModified:
          Number.isFinite(file.lastModified) && file.lastModified > 0
            ? new Date(file.lastModified).toISOString()
            : undefined,
      };
      completed += 1;
      options.onProgress?.({ completed, total: files.length, path });
    }
  };
  await Promise.all(
    Array.from(
      { length: Math.min(concurrency, Math.max(1, files.length)) },
      worker,
    ),
  );
  entries.sort((left, right) =>
    left.path < right.path ? -1 : left.path > right.path ? 1 : 0,
  );
  const rootLabel = commonRootLabel(files);
  return {
    schema: "de.add-ideas.diff-tools.directory-manifest.v1",
    schemaVersion: 1,
    generatedLocally: true,
    rootLabel,
    hashAlgorithm: "SHA-256",
    entries,
    totals: { files: entries.length, bytes: totalBytes },
  };
 }
 export function compareDirectoryManifests(
  left: DirectoryManifest,
  right: DirectoryManifest,
 ): ManifestChange[] {
  validateDirectoryManifest(left);
  validateDirectoryManifest(right);
  const leftEntries = new Map(left.entries.map((entry) => [entry.path, entry]));
  const rightEntries = new Map(
    right.entries.map((entry) => [entry.path, entry]),
  );
  const paths = [
    ...new Set([...leftEntries.keys(), ...rightEntries.keys()]),
  ].sort();
  return paths.map((path) => {
    const before = leftEntries.get(path);
    const after = rightEntries.get(path);
    if (!before)
      return {
        path,
        status: "added",
        right: after,
        detail: "File exists only on the right.",
      };
    if (!after)
      return {
        path,
        status: "removed",
        left: before,
        detail: "File exists only on the left.",
      };
    if (before.sha256 === after.sha256 && before.bytes === after.bytes)
      return {
        path,
        status: "same",
        left: before,
        right: after,
        detail: "Size and SHA-256 digest match.",
      };
    return {
      path,
      status: "modified",
      left: before,
      right: after,
      detail:
        before.bytes === after.bytes
          ? "SHA-256 digest changed while byte size stayed equal."
          : "Byte size and/or SHA-256 digest changed.",
    };
  });
 }
 export function serializeDirectoryManifest(
  manifest: DirectoryManifest,
 ): string {
  validateDirectoryManifest(manifest);
  const text = `${JSON.stringify(manifest, null, 2)}\n`;
  if (text.length > DIFF_LIMITS.maxOutputCharacters)
    throw new RangeError("Directory manifest exceeds the output limit.");
  return text;
 }
 export function parseDirectoryManifest(source: string): DirectoryManifest {
  if (source.length > DIFF_LIMITS.maxOutputCharacters)
    throw new RangeError("Directory manifest exceeds the input limit.");
  let value: unknown;
  try {
    value = JSON.parse(source) as unknown;
  } catch (error) {
    throw new SyntaxError(
      error instanceof Error ? error.message : "Invalid manifest JSON.",
      { cause: error },
    );
  }
  validateDirectoryManifest(value);
  return value;
 }
 export function validateDirectoryManifest(
  value: unknown,
 ): asserts value is DirectoryManifest {
  if (!value || typeof value !== "object" || Array.isArray(value))
    throw new TypeError("Directory manifest must be an object.");
  const record = value as Record<string, unknown>;
  if (
    record.schema !== "de.add-ideas.diff-tools.directory-manifest.v1" ||
    record.schemaVersion !== 1 ||
    record.generatedLocally !== true ||
    record.hashAlgorithm !== "SHA-256" ||
    !Array.isArray(record.entries)
  )
    throw new TypeError(
      "Directory manifest identity or entry list is invalid.",
    );
  if (record.entries.length > DIFF_LIMITS.maxDirectoryFiles)
    throw new RangeError("Directory manifest exceeds the file-count limit.");
  let total = 0;
  let previous = "";
  const seen = new Set<string>();
  const collisionKeys = new Set<string>();
  for (const candidate of record.entries) {
    if (!candidate || typeof candidate !== "object" || Array.isArray(candidate))
      throw new TypeError("Directory manifest entry is invalid.");
    const entry = candidate as Record<string, unknown>;
    if (
      typeof entry.path !== "string" ||
      typeof entry.bytes !== "number" ||
      !Number.isSafeInteger(entry.bytes) ||
      entry.bytes < 0 ||
      typeof entry.sha256 !== "string" ||
      !/^[0-9a-f]{64}$/u.test(entry.sha256) ||
      (entry.lastModified !== undefined &&
        (typeof entry.lastModified !== "string" ||
          !Number.isFinite(Date.parse(entry.lastModified))))
    )
      throw new TypeError("Directory manifest entry fields are invalid.");
    validatePath(entry.path);
    if (seen.has(entry.path))
      throw new Error(`Duplicate manifest path: ${entry.path}.`);
    const collisionKey = entry.path.normalize("NFC").toLocaleLowerCase("en-US");
    if (collisionKeys.has(collisionKey))
      throw new Error(
        `Directory path collision after conservative normalization: ${entry.path}.`,
      );
    if (previous && entry.path < previous)
      throw new Error("Directory manifest entries must be sorted by path.");
    seen.add(entry.path);
    collisionKeys.add(collisionKey);
    previous = entry.path;
    total += entry.bytes;
    if (!Number.isSafeInteger(total) || total > DIFF_LIMITS.maxDirectoryBytes)
      throw new RangeError(
        "Directory manifest exceeds the aggregate byte limit.",
      );
  }
  const totals = record.totals;
  if (
    !totals ||
    typeof totals !== "object" ||
    (totals as Record<string, unknown>).files !== record.entries.length ||
    (totals as Record<string, unknown>).bytes !== total
  )
    throw new Error("Directory manifest totals do not match its entries.");
 }
 function relativePaths(files: readonly File[]): string[] {
  const root = commonRootLabel(files);
  return files.map((file) => {
    const raw = file.webkitRelativePath || file.name;
    const segments = raw.split("/");
    if (root && segments[0] === root) segments.shift();
    const path = segments.join("/").normalize("NFC");
    validatePath(path);
    return path;
  });
 }
 function commonRootLabel(files: readonly File[]): string | undefined {
  const roots = files
    .map((file) => file.webkitRelativePath.split("/")[0])
    .filter((value): value is string => Boolean(value));
  return roots.length === files.length &&
    roots.every((root) => root === roots[0])
    ? roots[0]
    : undefined;
 }
 function validatePath(path: string): void {
  if (
    !path ||
    path.length > DIFF_LIMITS.maxDirectoryPathCharacters ||
    path.includes("\\") ||
    path.startsWith("/") ||
    /^[a-z]:/iu.test(path) ||
    hasControlCharacter(path)
  )
    throw new Error(
      `Unsafe or excessive directory path: ${path || "(empty)"}.`,
    );
  const segments = path.split("/");
  if (
    segments.length > DIFF_LIMITS.maxDirectoryPathSegments ||
    segments.some((segment) => !segment || segment === "." || segment === "..")
  )
    throw new Error(`Unsafe directory path segments: ${path}.`);
 }
 function hasControlCharacter(value: string): boolean {
  return [...value].some((character) => {
    const codePoint = character.codePointAt(0)!;
    return codePoint <= 0x1f || codePoint === 0x7f;
  });
 }
 function hex(bytes: Uint8Array): string {
  return [...bytes].map((byte) => byte.toString(16).padStart(2, "0")).join("");
 }
 function throwIfAborted(signal?: AbortSignal): void {
  if (signal?.aborted)
    throw signal.reason instanceof Error
      ? signal.reason
      : new DOMException("Operation cancelled.", "AbortError");
 }
@@ -14,7 +14,15 @@ export const DIFF_LIMITS = Object.freeze({
  maxOutputCharacters: 16_000_000,
  maxRowSnippet: 12_000,
  diffTimeoutMilliseconds: 2_000,
  workerTimeoutMilliseconds: 15_000,
  maxEditLength: 10_000,
  maxDirectoryFiles: 5_000,
  maxDirectoryBytes: 512 * 1024 * 1024,
  maxDirectoryFileBytes: 256 * 1024 * 1024,
  maxDirectoryPathCharacters: 4_096,
  maxDirectoryPathSegments: 64,
  directoryHashConcurrency: 2,
  maxMergeConflicts: 1_000,
 });
 export class DiffLimitError extends RangeError {
@@ -0,0 +1,286 @@
 import { diffArrays } from "diff";
 import { assertInput, assertOutput, DIFF_LIMITS } from "./limits";
 import type { Diagnostic } from "./types";
 interface Edit {
  readonly start: number;
  readonly end: number;
  readonly replacement: readonly string[];
  readonly side: "ours" | "theirs";
 }
 export interface MergeRequest {
  readonly base: string;
  readonly ours: string;
  readonly theirs: string;
  readonly oursName?: string;
  readonly theirsName?: string;
 }
 export interface MergeConflict {
  readonly index: number;
  readonly baseStartLine: number;
  readonly baseEndLine: number;
  readonly ours: string;
  readonly base: string;
  readonly theirs: string;
 }
 export interface MergeResult {
  readonly text: string;
  readonly clean: boolean;
  readonly conflicts: readonly MergeConflict[];
  readonly diagnostics: readonly Diagnostic[];
  readonly report: string;
 }
 export function mergeThreeWay(request: MergeRequest): MergeResult {
  assertInput(request.base, "left");
  assertInput(request.ours, "right");
  assertInput(request.theirs, "right");
  if (request.ours === request.theirs)
    return result(
      request,
      request.ours,
      [],
      [notice("merge.identical-sides", "Both variants are identical.")],
    );
  if (request.ours === request.base)
    return result(
      request,
      request.theirs,
      [],
      [notice("merge.ours-unchanged", "Only the other variant changed.")],
    );
  if (request.theirs === request.base)
    return result(
      request,
      request.ours,
      [],
      [notice("merge.theirs-unchanged", "Only our variant changed.")],
    );
  const base = lineTokens(request.base);
  const ours = editsFor(base, lineTokens(request.ours), "ours");
  const theirs = editsFor(base, lineTokens(request.theirs), "theirs");
  const all = [...ours, ...theirs].sort(
    (left, right) =>
      left.start - right.start ||
      left.end - right.end ||
      left.side.localeCompare(right.side),
  );
  const output: string[] = [];
  const conflicts: MergeConflict[] = [];
  let cursor = 0;
  let index = 0;
  while (index < all.length) {
    const first = all[index]!;
    output.push(...base.slice(cursor, first.start));
    const regionStart = first.start;
    let regionEnd = first.end;
    const group: Edit[] = [first];
    index += 1;
    while (index < all.length) {
      const candidate = all[index]!;
      const overlaps =
        candidate.start < regionEnd ||
        (regionStart === regionEnd && candidate.start === regionStart);
      if (!overlaps) break;
      group.push(candidate);
      regionEnd = Math.max(regionEnd, candidate.end);
      index += 1;
    }
    const oursGroup = group.filter((edit) => edit.side === "ours");
    const theirsGroup = group.filter((edit) => edit.side === "theirs");
    const baseRegion = base.slice(regionStart, regionEnd);
    const oursRegion = oursGroup.length
      ? applyRegion(base, regionStart, regionEnd, oursGroup)
      : baseRegion;
    const theirsRegion = theirsGroup.length
      ? applyRegion(base, regionStart, regionEnd, theirsGroup)
      : baseRegion;
    if (equalTokens(oursRegion, theirsRegion)) output.push(...oursRegion);
    else if (equalTokens(oursRegion, baseRegion)) output.push(...theirsRegion);
    else if (equalTokens(theirsRegion, baseRegion)) output.push(...oursRegion);
    else {
      if (conflicts.length >= DIFF_LIMITS.maxMergeConflicts)
        throw new RangeError(
          "Three-way merge exceeds the conflict-count limit.",
        );
      const conflict: MergeConflict = {
        index: conflicts.length + 1,
        baseStartLine: lineNumberAt(base, regionStart),
        baseEndLine: lineNumberAt(base, regionEnd),
        ours: oursRegion.join(""),
        base: baseRegion.join(""),
        theirs: theirsRegion.join(""),
      };
      conflicts.push(conflict);
      output.push(
        marker(`<<<<<<< ${safeLabel(request.oursName, "ours")}`),
        ...withSectionEnding(oursRegion),
        marker("||||||| base"),
        ...withSectionEnding(baseRegion),
        marker("======="),
        ...withSectionEnding(theirsRegion),
        marker(`>>>>>>> ${safeLabel(request.theirsName, "theirs")}`),
      );
    }
    cursor = regionEnd;
  }
  output.push(...base.slice(cursor));
  return result(
    request,
    output.join(""),
    conflicts,
    conflicts.length
      ? [
          {
            code: "merge.conflicts",
            message: `${conflicts.length} conflict(s) require review.`,
            severity: "warning",
            side: "both",
          },
        ]
      : [
          notice(
            "merge.clean",
            "Changes were merged without overlapping edits.",
          ),
        ],
  );
 }
 function editsFor(
  base: string[],
  variant: string[],
  side: Edit["side"],
 ): Edit[] {
  const changes = diffArrays(base, variant, {
    timeout: DIFF_LIMITS.diffTimeoutMilliseconds,
    maxEditLength: DIFF_LIMITS.maxEditLength,
  });
  if (!changes)
    throw new RangeError(
      "Three-way merge exceeded the edit-distance or time limit.",
    );
  const edits: Edit[] = [];
  let cursor = 0;
  let index = 0;
  while (index < changes.length) {
    const change = changes[index]!;
    if (!change.added && !change.removed) {
      cursor += change.value.length;
      index += 1;
      continue;
    }
    const start = cursor;
    const replacement: string[] = [];
    while (index < changes.length) {
      const part = changes[index]!;
      if (!part.added && !part.removed) break;
      if (part.removed) cursor += part.value.length;
      if (part.added) replacement.push(...part.value);
      index += 1;
    }
    edits.push({ start, end: cursor, replacement, side });
  }
  return edits;
 }
 function applyRegion(
  base: string[],
  start: number,
  end: number,
  edits: Edit[],
 ): string[] {
  const output: string[] = [];
  let cursor = start;
  for (const edit of edits.sort(
    (left, right) => left.start - right.start || left.end - right.end,
  )) {
    output.push(...base.slice(cursor, edit.start), ...edit.replacement);
    cursor = edit.end;
  }
  output.push(...base.slice(cursor, end));
  return output;
 }
 function lineTokens(value: string): string[] {
  if (!value) return [];
  const tokens = value.match(/[^\r\n]*(?:\r\n|\r|\n)|[^\r\n]+$/gu) ?? [];
  if (tokens.length > DIFF_LIMITS.maxTokensPerSide)
    throw new RangeError("Three-way merge exceeds the line-token limit.");
  return tokens;
 }
 function equalTokens(
  left: readonly string[],
  right: readonly string[],
 ): boolean {
  return (
    left.length === right.length &&
    left.every((value, index) => value === right[index])
  );
 }
 function marker(value: string): string {
  return `${value}\n`;
 }
 function withSectionEnding(tokens: readonly string[]): string[] {
  if (!tokens.length) return [];
  const output = [...tokens];
  const last = output.at(-1)!;
  if (!/(?:\r\n|\r|\n)$/u.test(last)) output[output.length - 1] = `${last}\n`;
  return output;
 }
 function safeLabel(value: string | undefined, fallback: string): string {
  return (value || fallback).replace(/[\r\n]/gu, " ").slice(0, 100);
 }
 function lineNumberAt(tokens: readonly string[], offset: number): number {
  return tokens
    .slice(0, offset)
    .reduce(
      (lines, token) => lines + (/(?:\r\n|\r|\n)$/u.test(token) ? 1 : 0),
      1,
    );
 }
 function notice(code: string, message: string): Diagnostic {
  return { code, message, severity: "info", side: "both" };
 }
 function result(
  request: MergeRequest,
  text: string,
  conflicts: MergeConflict[],
  diagnostics: Diagnostic[],
 ): MergeResult {
  const bounded = assertOutput(text, "Merged output length");
  const reportObject = {
    schema: "de.add-ideas.diff-tools.merge-report.v1",
    schemaVersion: 1,
    generatedLocally: true,
    clean: conflicts.length === 0,
    conflicts,
    diagnostics,
    inputCharacters: {
      base: request.base.length,
      ours: request.ours.length,
      theirs: request.theirs.length,
    },
  };
  return {
    text: bounded,
    clean: conflicts.length === 0,
    conflicts,
    diagnostics,
    report: assertOutput(
      `${JSON.stringify(reportObject, null, 2)}\n`,
      "Merge report length",
    ),
  };
 }
@@ -1,4 +1,9 @@
 import {
  startWorkerJob,
  WorkerJobTimeoutError,
 } from "@add-ideas/toolbox-helpers";
 import { compareInputs } from "./compare";
 import { DIFF_LIMITS } from "./limits";
 import {
  DiffToolsError,
  type CompareRequest,
@@ -6,19 +11,17 @@ import {
  type DiffResult,
 } from "./types";
-type WorkerResponse =
+interface SerializedCompareError {
-  | { id: number; ok: true; result: DiffResult }
+  message: string;
-  | { id: number; ok: false; message: string; diagnostics: Diagnostic[] };
+  diagnostics: Diagnostic[];
 }
 export interface CompareTask {
  promise: Promise<DiffResult>;
  cancel(): void;
 }
 let nextId = 0;
 export function createCompareTask(request: CompareRequest): CompareTask {
  const id = ++nextId;
  if (typeof Worker === "undefined") {
    let cancelled = false;
    return {
@@ -36,42 +39,56 @@ export function createCompareTask(request: CompareRequest): CompareTask {
    new URL("../workers/diff.worker.ts", import.meta.url),
    { type: "module", name: "diff-tools-comparator" },
  );
-  let settled = false;
+  const task = startWorkerJob<
-  let rejectPromise: ((reason?: unknown) => void) | undefined;
+    CompareRequest,
-  const promise = new Promise<DiffResult>((resolve, reject) => {
+    DiffResult,
-    rejectPromise = reject;
+    never,
-    worker.onmessage = (event: MessageEvent<WorkerResponse>) => {
+    SerializedCompareError
-      if (event.data.id !== id || settled) return;
+  >(worker, request, {
-      settled = true;
+    timeoutMs: DIFF_LIMITS.workerTimeoutMilliseconds,
-      worker.terminate();
+    deserializeError: (error) =>
-      if (event.data.ok) resolve(event.data.result);
+      new DiffToolsError(error.message, error.diagnostics),
-      else
+    workerFailureMessage: "The comparison worker failed.",
-        reject(new DiffToolsError(event.data.message, event.data.diagnostics));
+  });
-    };
+  const promise = task.promise.catch((error: unknown) => {
-    worker.onerror = (event) => {
+    if (error instanceof WorkerJobTimeoutError) {
-      if (settled) return;
+      throw new DiffToolsError(
-      settled = true;
+        `Comparison exceeded the ${DIFF_LIMITS.workerTimeoutMilliseconds / 1000}-second worker safety limit.`,
-      worker.terminate();
+        [
      reject(
        new DiffToolsError(event.message || "The comparison worker failed.", [
          {
-            code: "worker.failure",
+            code: "worker.timeout",
-            message: event.message || "The comparison worker failed.",
+            message:
              "The disposable comparison worker was terminated before it completed.",
            severity: "error",
            side: "both",
          },
-        ]),
+        ],
      );
-    };
+    }
-    worker.postMessage({ id, request });
+    if (
      error instanceof DiffToolsError ||
      (error instanceof DOMException && error.name === "AbortError")
    )
      throw error;
    throw new DiffToolsError(
      error instanceof Error ? error.message : "The comparison worker failed.",
      [
        {
          code: "worker.failure",
          message:
            error instanceof Error
              ? error.message
              : "The comparison worker failed.",
          severity: "error",
          side: "both",
        },
      ],
    );
  });
  return {
    promise,
    cancel() {
-      if (settled) return;
+      task.cancel("Comparison cancelled.");
      settled = true;
      worker.terminate();
      rejectPromise?.(new DOMException("Comparison cancelled.", "AbortError"));
    },
  };
 }
@@ -115,13 +115,27 @@ textarea {
 .hero,
 .panel,
 .mode-tabs,
-.result-tabs {
+.result-tabs,
 .workspace-tabs {
  border: 1px solid var(--toolbox-border);
  border-radius: 0.9rem;
  background: var(--toolbox-surface);
  box-shadow: 0 8px 28px rgb(30 36 70 / 4%);
 }
 .workspace-tabs {
  display: flex;
  gap: 0.35rem;
  padding: 0.35rem;
  overflow-x: auto;
 }
 .workspace-tabs button[aria-current="page"] {
  border-color: var(--toolbox-accent);
  background: var(--toolbox-accent);
  color: var(--toolbox-accent-contrast);
 }
 .hero {
  display: flex;
  justify-content: space-between;
@@ -179,40 +193,122 @@ textarea {
  margin-bottom: 0.9rem;
 }
 .button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  align-items: center;
 }
 .directory-inputs {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.8rem;
  margin: 0.9rem 0;
 }
 .directory-inputs article {
  min-width: 0;
  padding: 0.8rem;
  border: 1px solid var(--toolbox-border);
  border-radius: 0.7rem;
  background: var(--toolbox-surface-soft);
 }
 .directory-inputs article p,
 .option-note {
  color: var(--toolbox-muted);
  font-size: 0.78rem;
  line-height: 1.5;
 }
 .manifest-filter {
  margin: 1rem 0 0.65rem;
 }
 .table-scroll {
  max-height: 34rem;
  overflow: auto;
  border: 1px solid var(--toolbox-border);
  border-radius: 0.7rem;
 }
 .table-scroll table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.78rem;
 }
 .table-scroll th,
 .table-scroll td {
  padding: 0.55rem 0.65rem;
  border-bottom: 1px solid var(--toolbox-border);
  text-align: left;
  vertical-align: top;
 }
 .table-scroll thead th {
  position: sticky;
  top: 0;
  z-index: 1;
  background: var(--toolbox-surface-soft);
 }
 .merge-inputs {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.75rem;
  margin: 0.9rem 0;
 }
 .merge-inputs textarea {
  min-height: 14rem;
 }
 .merge-result {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--toolbox-border);
 }
 .merge-result textarea {
  min-height: 22rem;
 }
 .mode-tabs,
 .result-tabs {
  padding: 0.35rem;
  overflow-x: auto;
 }
-.mode-tabs [role="tablist"],
+.mode-tabs [role="group"],
-.result-tabs [role="tablist"] {
+.result-tabs [role="group"] {
  display: flex;
  gap: 0.35rem;
  min-width: max-content;
 }
-.mode-tabs [role="tab"] {
+.mode-tabs button {
  min-width: 9.5rem;
  flex-direction: column;
  align-items: flex-start;
  line-height: 1.2;
 }
-.mode-tabs [role="tab"] small {
+.mode-tabs button small {
  color: var(--toolbox-muted);
  font-size: 0.7rem;
  font-weight: 580;
 }
-.mode-tabs [role="tab"][aria-selected="true"],
+.mode-tabs button[aria-pressed="true"],
-.result-tabs [role="tab"][aria-selected="true"] {
+.result-tabs button[aria-pressed="true"] {
  border-color: var(--toolbox-accent);
  background: var(--toolbox-accent);
  color: var(--toolbox-accent-contrast);
 }
-.mode-tabs [role="tab"][aria-selected="true"] small {
+.mode-tabs button[aria-pressed="true"] small {
  color: inherit;
  opacity: 0.84;
 }
@@ -734,7 +830,9 @@ textarea {
@media (max-width: 52rem) {
  .input-grid,
  .metadata-grid,
-  .paired-lines {
+  .paired-lines,
  .directory-inputs,
  .merge-inputs {
    grid-template-columns: 1fr;
  }
  .paired-lines > div + div {
@@ -3,12 +3,22 @@
  "schemaVersion": 1,
  "id": "de.add-ideas.diff-tools",
  "name": "Diff Tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
-  "description": "Compare text and structured data locally in the browser.",
+  "description": "Compare files and directories or perform bounded three-way merges locally.",
  "entry": "./",
  "icon": "./favicon.svg",
  "categories": ["developer", "files", "productivity"],
-  "tags": ["diff", "compare", "json", "xml", "csv", "patch"],
+  "tags": [
    "diff",
    "compare",
    "json",
    "xml",
    "csv",
    "patch",
    "directory",
    "manifest",
    "merge"
  ],
  "integration": {
    "contextVersion": 1,
    "launchModes": ["navigate", "new-tab"],
@@ -21,6 +31,46 @@
    "crossOriginIsolated": false,
    "topLevelContext": false
  },
  "io": {
    "accepts": [
      {
        "mediaType": "text/*",
        "extensions": [".txt", ".md", ".csv", ".xml"],
        "label": "Text, CSV and XML files"
      },
      {
        "mediaType": "application/json",
        "extensions": [".json"],
        "label": "JSON documents and directory manifests"
      },
      {
        "mediaType": "*/*",
        "extensions": [],
        "label": "Files selected for bounded directory hashing"
      }
    ],
    "produces": [
      {
        "mediaType": "text/x-diff",
        "extensions": [".diff", ".patch"],
        "label": "Unified and JSON patches"
      },
      {
        "mediaType": "text/plain",
        "extensions": [".txt"],
        "label": "Three-way merge result"
      },
      {
        "mediaType": "application/json",
        "extensions": [".json"],
        "label": "Diff, merge and directory-manifest reports"
      }
    ]
  },
  "capabilities": {
    "required": ["workers"],
    "optional": ["web-crypto"]
  },
  "privacy": {
    "processing": "local",
    "fileUploads": true,
@@ -1 +1 @@
-export const APP_VERSION = "0.1.0";
+export const APP_VERSION = "0.2.0";
@@ -1,30 +1,17 @@
 /// <reference lib="webworker" />
 import { createWorkerJobMessageHandler } from "@add-ideas/toolbox-helpers";
 import { compareInputs, serializeFailure } from "../core/compare";
 import type { CompareRequest, DiffResult } from "../core/types";
-interface WorkerRequest {
+self.onmessage = createWorkerJobMessageHandler<
-  id: number;
+  CompareRequest,
-  request: CompareRequest;
+  DiffResult,
-}
+  never,
-
+  ReturnType<typeof serializeFailure>
-type WorkerResponse =
+>(
-  | { id: number; ok: true; result: DiffResult }
+  (request) => compareInputs(request),
-  | {
+  (response) => self.postMessage(response),
-      id: number;
+  { serializeError: serializeFailure },
-      ok: false;
+);
      message: string;
      diagnostics: ReturnType<typeof serializeFailure>["diagnostics"];
    };
 self.onmessage = (event: MessageEvent<WorkerRequest>) => {
  const { id, request } = event.data;
  let response: WorkerResponse;
  try {
    response = { id, ok: true, result: compareInputs(request) };
  } catch (error) {
    response = { id, ok: false, ...serializeFailure(error) };
  }
  self.postMessage(response);
 };
 export {};
@@ -25,7 +25,9 @@ function auditPage(page: Page) {
 async function openApp(page: Page) {
  await page.goto(APP_PATH);
  await expect(
-    page.getByRole("heading", { name: "Diff Tools", exact: true }),
+    page
      .locator(".hero")
      .getByRole("heading", { name: "Diff Tools", exact: true }),
  ).toBeVisible();
  await expect(page.getByText(/substantive change row/u)).toBeVisible();
 }
@@ -60,19 +62,19 @@ test("exports exact-decimal JSON Patch without losing the prior result", async (
 }) => {
  const audit = auditPage(page);
  await openApp(page);
-  await page.getByRole("tab", { name: /JSON Semantic/u }).click();
+  await page.getByRole("button", { name: /JSON Semantic/u }).click();
  await page.getByTestId("left-editor").fill('{"amount":1,"keep":true}');
  await page
    .getByTestId("right-editor")
    .fill('{"amount":9007199254740993123456789,"keep":true}');
  await page.getByRole("button", { name: "Compare now" }).click();
  await expect(page.getByText(/1 substantive change row/u)).toBeVisible();
-  await page.getByRole("tab", { name: "Patches" }).click();
+  await page.getByRole("button", { name: "Patches" }).click();
  await expect(page.getByTestId("json-patch")).toContainText(
    "9007199254740993123456789",
  );
-  await page.getByRole("tab", { name: /XML Namespace-aware/u }).click();
+  await page.getByRole("button", { name: /XML Namespace-aware/u }).click();
  await expect(page.getByText(/substantive change row/u)).toBeVisible();
  const previousVerdict = page.getByText("Different", { exact: true }).first();
  await expect(previousVerdict).toBeVisible();
@@ -87,7 +89,7 @@ test("exports exact-decimal JSON Patch without losing the prior result", async (
 test("opens local keyed CSV and reports duplicate keys", async ({ page }) => {
  const audit = auditPage(page);
  await openApp(page);
-  await page.getByRole("tab", { name: /CSV \/ TSV Keyed rows/u }).click();
+  await page.getByRole("button", { name: /CSV \/ TSV Keyed rows/u }).click();
  await page.getByTestId("left-file-input").setInputFiles({
    name: "duplicates.csv",
    mimeType: "text/csv",
@@ -118,8 +120,51 @@ test("serves the release identity and hardened headers", async ({
  const manifest = await request.get(`${APP_PATH}toolbox-app.json`);
  await expect(manifest.json()).resolves.toMatchObject({
    id: "de.add-ideas.diff-tools",
-    version: "0.1.0",
+    version: "0.2.0",
    entry: "./",
    privacy: { processing: "local", fileUploads: true, telemetry: false },
  });
 });
 test("runs the bounded three-way merge workspace", async ({ page }) => {
  await page.goto("/deep/nested/diff/");
  await page.getByRole("button", { name: "Three-way merge" }).click();
  await page.getByLabel("Base").fill("one\ntwo\nthree\n");
  await page.getByLabel("Ours").fill("ONE\ntwo\nthree\n");
  await page.getByLabel("Theirs").fill("one\ntwo\nTHREE\n");
  await page.getByRole("button", { name: "Merge locally" }).click();
  await expect(page.getByTestId("merge-output")).toHaveValue(
    "ONE\ntwo\nTHREE\n",
  );
  await expect(
    page.getByRole("heading", { name: "0 conflict(s)" }),
  ).toBeVisible();
 });
 test("imports and compares portable directory manifests", async ({ page }) => {
  await page.goto("/deep/nested/diff/");
  await page.getByRole("button", { name: "Directories" }).click();
  const manifest = (digest: string) => ({
    schema: "de.add-ideas.diff-tools.directory-manifest.v1",
    schemaVersion: 1,
    generatedLocally: true,
    hashAlgorithm: "SHA-256",
    entries: [{ path: "file.txt", bytes: 4, sha256: digest }],
    totals: { files: 1, bytes: 4 },
  });
  const inputs = page.locator('input[accept*="application/json"]');
  await inputs.nth(0).setInputFiles({
    name: "left.json",
    mimeType: "application/json",
    buffer: Buffer.from(JSON.stringify(manifest("a".repeat(64)))),
  });
  await inputs.nth(1).setInputFiles({
    name: "right.json",
    mimeType: "application/json",
    buffer: Buffer.from(JSON.stringify(manifest("b".repeat(64)))),
  });
  await page.getByRole("button", { name: "Build & compare manifests" }).click();
  await expect(
    page.getByRole("row", { name: /file\.txt modified/iu }),
  ).toBeVisible();
 });
@@ -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/diff/");
  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);
 });
@@ -10,7 +10,7 @@ describe("Diff Tools workbench", () => {
    expect(screen.getByText("Browser-local")).toBeVisible();
    expect(await screen.findByText(/substantive change row/u)).toBeVisible();
    expect(screen.getAllByText("CRLF").length).toBeGreaterThan(0);
-    await user.click(screen.getByRole("tab", { name: "Side by side" }));
+    await user.click(screen.getByRole("button", { name: "Side by side" }));
    expect(
      screen.getByRole("table", { name: "Side-by-side differences" }),
    ).toBeVisible();
@@ -19,7 +19,7 @@ describe("Diff Tools workbench", () => {
  it("keeps exact large numbers in the RFC 6902 artifact", async () => {
    const user = userEvent.setup();
    render(<Workbench />);
-    await user.click(screen.getByRole("tab", { name: /JSON Semantic/u }));
+    await user.click(screen.getByRole("button", { name: /JSON Semantic/u }));
    fireEvent.change(screen.getByTestId("left-editor"), {
      target: { value: '{"n":1}' },
    });
@@ -30,7 +30,7 @@ describe("Diff Tools workbench", () => {
    await waitFor(() =>
      expect(screen.getByText(/1 substantive change row/u)).toBeVisible(),
    );
-    await user.click(screen.getByRole("tab", { name: "Patches" }));
+    await user.click(screen.getByRole("button", { name: "Patches" }));
    expect(
      (screen.getByTestId("json-patch") as HTMLTextAreaElement).value,
    ).toContain("9007199254740993123456789");
@@ -39,7 +39,9 @@ describe("Diff Tools workbench", () => {
  it("keeps the last successful XML result visible beside an error", async () => {
    const user = userEvent.setup();
    render(<Workbench />);
-    await user.click(screen.getByRole("tab", { name: /XML Namespace-aware/u }));
+    await user.click(
      screen.getByRole("button", { name: /XML Namespace-aware/u }),
    );
    expect(await screen.findByText(/substantive change row/u)).toBeVisible();
    const verdict = screen.getByText("Different", { exact: true });
    fireEvent.change(screen.getByTestId("left-editor"), {
@@ -0,0 +1,140 @@
 import { describe, expect, it } from "vitest";
 import {
  compareDirectoryManifests,
  createDirectoryManifest,
  parseDirectoryManifest,
  serializeDirectoryManifest,
 } from "../../src/core/directory-manifest";
 import { mergeThreeWay } from "../../src/core/merge";
 function file(path: string, value: string): File {
  const item = new File([value], path.split("/").at(-1)!, {
    lastModified: Date.UTC(2026, 0, 1),
  });
  Object.defineProperty(item, "webkitRelativePath", {
    value: `chosen-root/${path}`,
  });
  return item;
 }
 describe("directory manifests", () => {
  it("hashes bounded files deterministically and strips the selected root", async () => {
    const first = await createDirectoryManifest([
      file("z.txt", "last"),
      file("nested/a.txt", "first"),
    ]);
    const second = await createDirectoryManifest([
      file("nested/a.txt", "first"),
      file("z.txt", "last"),
    ]);
    expect(first.entries.map((entry) => entry.path)).toEqual([
      "nested/a.txt",
      "z.txt",
    ]);
    expect(first.entries).toEqual(second.entries);
    expect(parseDirectoryManifest(serializeDirectoryManifest(first))).toEqual(
      first,
    );
  });
  it("compares content digests rather than timestamps", async () => {
    const left = await createDirectoryManifest([
      file("same.txt", "same"),
      file("changed.txt", "before"),
      file("removed.txt", "gone"),
    ]);
    const right = await createDirectoryManifest([
      file("same.txt", "same"),
      file("changed.txt", "after"),
      file("added.txt", "new"),
    ]);
    expect(
      compareDirectoryManifests(left, right).map(({ path, status }) => ({
        path,
        status,
      })),
    ).toEqual([
      { path: "added.txt", status: "added" },
      { path: "changed.txt", status: "modified" },
      { path: "removed.txt", status: "removed" },
      { path: "same.txt", status: "same" },
    ]);
  });
  it("rejects traversal and inconsistent imported totals", async () => {
    await expect(
      createDirectoryManifest([file("../escape.txt", "bad")]),
    ).rejects.toThrow(/unsafe/iu);
    const manifest = await createDirectoryManifest([file("safe.txt", "ok")]);
    const serialized = JSON.stringify({
      ...manifest,
      totals: { files: 1, bytes: 999 },
    });
    expect(() => parseDirectoryManifest(serialized)).toThrow(/totals/iu);
  });
  it("rejects case-normalized collisions and invalid timestamps on import", async () => {
    const manifest = await createDirectoryManifest([file("safe.txt", "ok")]);
    const duplicate = {
      ...manifest,
      entries: [
        manifest.entries[0],
        { ...manifest.entries[0], path: "SAFE.txt" },
      ],
      totals: { files: 2, bytes: manifest.totals.bytes * 2 },
    };
    expect(() => parseDirectoryManifest(JSON.stringify(duplicate))).toThrow(
      /collision/iu,
    );
    expect(() =>
      parseDirectoryManifest(
        JSON.stringify({
          ...manifest,
          entries: [{ ...manifest.entries[0], lastModified: "not-a-date" }],
        }),
      ),
    ).toThrow(/fields/iu);
  });
 });
 describe("bounded three-way merge", () => {
  it("combines non-overlapping line changes without conflict", () => {
    const result = mergeThreeWay({
      base: "one\ntwo\nthree\n",
      ours: "ONE\ntwo\nthree\n",
      theirs: "one\ntwo\nTHREE\n",
    });
    expect(result.clean).toBe(true);
    expect(result.text).toBe("ONE\ntwo\nTHREE\n");
  });
  it("emits explicit ours/base/theirs markers for overlapping changes", () => {
    const result = mergeThreeWay({
      base: "same\nvalue\n",
      ours: "same\nours\n",
      theirs: "same\ntheirs\n",
      oursName: "working.txt",
      theirsName: "incoming.txt",
    });
    expect(result.clean).toBe(false);
    expect(result.conflicts).toHaveLength(1);
    expect(result.text).toContain("<<<<<<< working.txt");
    expect(result.text).toContain("||||||| base");
    expect(result.text).toContain(">>>>>>> incoming.txt");
    expect(JSON.parse(result.report)).toMatchObject({
      schema: "de.add-ideas.diff-tools.merge-report.v1",
      clean: false,
    });
  });
  it("keeps conflict markers on their own lines when inputs lack final newlines", () => {
    const result = mergeThreeWay({
      base: "base",
      ours: "ours",
      theirs: "theirs",
    });
    expect(result.text).toBe(
      "<<<<<<< ours\nours\n||||||| base\nbase\n=======\ntheirs\n>>>>>>> theirs\n",
    );
  });
 });
`@@ -1 +1 @@`
	`export const APP_VERSION = "0.1.0";`	`export const APP_VERSION = "0.2.0";`