diff --git a/.gitea/workflows/verify.yml b/.gitea/workflows/verify.yml
new file mode 100644
index 0000000..b84a7cb
--- /dev/null
+++ b/.gitea/workflows/verify.yml
@@ -0,0 +1,39 @@
+name: Verify
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: verify-${{ gitea.repository }}-${{ gitea.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    env:
+      CI: "true"
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: npm
+      - name: Select declared npm version
+        run: npm install --global npm@11.17.0
+      - name: Install dependencies
+        run: npm ci
+      - name: Audit runtime dependencies
+        run: npm audit --omit=dev --audit-level=moderate
+      - name: Check, test, and build
+        run: npm run check
+      - name: Install browser engines
+        run: npx playwright install --with-deps chromium firefox webkit
+      - name: Browser tests
+        run: npm run test:browser
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 36e1840..98316f6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 0.2.0 - 2026-09-02
+
+- Added exact atomic text-patch application/reversal against explicit local
+  snapshots with deterministic JSON/ZIP export.
+- Added layered ignore sources and tracked-state explanations, root
+  `.gitattributes` evaluation, and advisory release planning from Conventional
+  Commit headers.
+
 ## 0.1.0 - 2026-09-01
 
 - Added the initial local-first Git Tools workbench.
diff --git a/README.md b/README.md
index 6336090..83a9074 100644
--- a/README.md
+++ b/README.md
@@ -8,12 +8,15 @@ Git Tools is a standalone local-first application in the [add·ideas Toolbox](ht
 
 - Unified and `git diff` patch parsing with file status, modes, renames, hunk counts, line numbers, statistics, binary markers, and diagnostics
 - Unified patch authoring from before/after text with bounded LCS, context selection, path safety, and missing-final-newline markers
-- Root `.gitignore` matching for comments, escapes, globstars, character classes, directory rules, negation, ordered explanations, and ignored-parent diagnostics
+- Exact, atomic text-patch application and reversal against an explicit JSON repository snapshot, with downloadable JSON or deterministic ZIP output and no working-tree access
+- Layered `.gitignore` matching for comments, escapes, globstars, character classes, directory rules, negation, global excludes, `.git/info/exclude`, parent-to-child nested files, explicit tracked state, winning-rule explanations, and ignored-parent diagnostics
+- Root `.gitattributes` evaluation with set/unset/value/unspecified states, last-match provenance, and directory-pattern diagnostics
 - Strict SemVer 2.0 precedence plus common exact, comparator, partial, wildcard, hyphen, tilde, caret, AND, and OR ranges
 - Conventional Commit builder and structural lint with breaking-change/footer diagnostics
 - Keep-a-Changelog heading/section normalization, stable ordering, and duplicate-entry removal
+- Advisory release planning from Conventional Commit headers: SemVer bump, grouped notes, tag name, invalid-input evidence, and review-only command sequence
 
-Patch and before/after inputs are capped at 4 MiB with additional file, line, hunk, and diff-matrix bounds. `.gitignore` evaluates one repository-root file only; it does not read nested ignore files, global excludes, index state, or submodules. No workspace or `.git` directory is accessed. See [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) and [docs/PRIVACY-SECURITY.md](docs/PRIVACY-SECURITY.md).
+Patch and before/after inputs are capped at 4 MiB with additional file, line, hunk, and diff-matrix bounds. Applied snapshots are text-only, exact-match, atomic, limited to 5,000 files/32 MiB, and never touch the working tree. Ignore inputs are an explicit local snapshot; command-line exclude rules and submodule repository boundaries are not modeled. Attribute macros and nested attribute files are not expanded. No workspace or `.git` directory is accessed. See [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) and [docs/PRIVACY-SECURITY.md](docs/PRIVACY-SECURITY.md).
 
 ## Development
 
@@ -27,7 +30,7 @@ npm run test:browser
 
 ## Release
 
-`npm run release:artifact` creates a deterministic `release/git-tools-0.1.0.zip` and checksum sidecar.
+`npm run release:artifact` creates a deterministic `release/git-tools-0.2.0.zip` and checksum sidecar.
 
 ## Licence
 
diff --git a/SOURCE.md b/SOURCE.md
index e3abdc4..d726cde 100644
--- a/SOURCE.md
+++ b/SOURCE.md
@@ -1,7 +1,7 @@
 # Corresponding source
 
-The corresponding source for Git Tools 0.1.0 is available at:
+The corresponding source for Git Tools 0.2.0 is available at:
 
-https://git.add-ideas.de/lotobo/git-tools/src/tag/v0.1.0
+https://git.add-ideas.de/lotobo/git-tools/src/tag/v0.2.0
 
 Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.
diff --git a/THIRD_PARTY_NOTICES.md b/THIRD_PARTY_NOTICES.md
index 34e3918..d74e8c1 100644
--- a/THIRD_PARTY_NOTICES.md
+++ b/THIRD_PARTY_NOTICES.md
@@ -1,12 +1,12 @@
 # Third-party notices
 
-Git Tools 0.1.0 directly depends on these runtime packages:
+Git Tools 0.2.0 directly depends on these runtime packages:
 
 | Package                          | Pinned version | Declared licence |
 | -------------------------------- | -------------: | ---------------- |
-| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0       |
-| `@add-ideas/toolbox-helpers`     |          0.1.0 | GPL-3.0-or-later |
-| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-contract`    |          0.3.0 | Apache-2.0       |
+| `@add-ideas/toolbox-helpers`     |          0.2.0 | GPL-3.0-or-later |
+| `@add-ideas/toolbox-shell-react` |          0.3.0 | Apache-2.0       |
 | `react`                          |         19.2.8 | MIT              |
 | `react-dom`                      |         19.2.8 | MIT              |
 
diff --git a/package-lock.json b/package-lock.json
index 3616057..f6a775b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,22 +1,23 @@
 {
   "name": "git-tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "git-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-helpers": "0.1.0",
-        "@add-ideas/toolbox-shell-react": "0.2.3",
+        "@add-ideas/toolbox-contract": "0.3.0",
+        "@add-ideas/toolbox-helpers": "0.2.0",
+        "@add-ideas/toolbox-shell-react": "0.3.0",
+        "fflate": "0.8.2",
         "react": "19.2.8",
         "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",
@@ -42,24 +43,24 @@
       }
     },
     "node_modules/@add-ideas/toolbox-contract": {
-      "version": "0.2.3",
-      "license": "Apache-2.0",
-      "engines": {
-        "node": ">=20"
-      }
+      "version": "0.3.0",
+      "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-dKrK7BjOFwqJaBfJuhKxZKIld4sH0AKjEn6a0yLnbdMUFY+fFv4VSLGV2tNSBD016gumc2iNqOjUj/ld7x4rtA==",
+      "license": "Apache-2.0"
     },
     "node_modules/@add-ideas/toolbox-helpers": {
-      "version": "0.1.0",
-      "license": "GPL-3.0-or-later",
-      "engines": {
-        "node": ">=22"
-      }
+      "version": "0.2.0",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-helpers/-/0.2.0/toolbox-helpers-0.2.0.tgz",
+      "integrity": "sha512-SdOqkw+P+3J3fa5iVkzb5P15rVepB001GNV21Oh8w0CZcVL+YRltgD/s+MVcTyrNijWQf3E5vtQON/3N2LLyKg==",
+      "license": "GPL-3.0-or-later"
     },
     "node_modules/@add-ideas/toolbox-shell-react": {
-      "version": "0.2.3",
+      "version": "0.3.0",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-shell-react/-/0.3.0/toolbox-shell-react-0.3.0.tgz",
+      "integrity": "sha512-74p6JzAOG0YCAKdlc1hLofV4ZIko7vb448S75cIiM88PKm93EHl5VD7g8YVyfM56Ui97UY9dmy+Whiq4sGzpsg==",
       "license": "Apache-2.0",
       "dependencies": {
-        "@add-ideas/toolbox-contract": "0.2.3"
+        "@add-ideas/toolbox-contract": "0.3.0"
       },
       "peerDependencies": {
         "react": ">=18 <20",
@@ -67,17 +68,16 @@
       }
     },
     "node_modules/@add-ideas/toolbox-testkit": {
-      "version": "0.2.3",
+      "version": "0.3.0",
+      "resolved": "https://git.add-ideas.de/api/packages/lotobo/npm/%40add-ideas%2Ftoolbox-testkit/-/0.3.0/toolbox-testkit-0.3.0.tgz",
+      "integrity": "sha512-4Fk+oSvZFspOMIXr8Xy040nhAaBsIQAzsGyXWSpjn3+k3yBKq7nB1r5zCHhsXzfdLzvPDAx2KcmSNOhM330D9w==",
       "dev": true,
       "license": "Apache-2.0",
       "dependencies": {
-        "@add-ideas/toolbox-contract": "0.2.3"
+        "@add-ideas/toolbox-contract": "0.3.0"
       },
       "bin": {
         "toolbox-check": "dist/cli.js"
-      },
-      "engines": {
-        "node": ">=20"
       }
     },
     "node_modules/@adobe/css-tools": {
@@ -2009,6 +2009,12 @@
         }
       }
     },
+    "node_modules/fflate": {
+      "version": "0.8.2",
+      "resolved": "https://registry.npmjs.org/fflate/-/fflate-0.8.2.tgz",
+      "integrity": "sha512-cPJU47OaAoCbg0pBvzsgpTPhmhqI5eJjh/JIu8tPj5q+T7iLvW/JAYUqmE7KOB4R1ZyEhzBaIQpQpardBF5z8A==",
+      "license": "MIT"
+    },
     "node_modules/file-entry-cache": {
       "version": "8.0.0",
       "dev": true,
diff --git a/package.json b/package.json
index ed5005d..f59872c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "git-tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Inspect and author Git interchange formats locally in the browser.",
   "license": "GPL-3.0-or-later",
   "author": "Albrecht Degering",
@@ -39,14 +39,15 @@
     "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-helpers": "0.1.0",
-    "@add-ideas/toolbox-shell-react": "0.2.3",
+    "@add-ideas/toolbox-contract": "0.3.0",
+    "@add-ideas/toolbox-helpers": "0.2.0",
+    "@add-ideas/toolbox-shell-react": "0.3.0",
+    "fflate": "0.8.2",
     "react": "19.2.8",
     "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",
diff --git a/playwright.config.ts b/playwright.config.ts
index 731da62..2ab6a22 100644
--- a/playwright.config.ts
+++ b/playwright.config.ts
@@ -15,7 +15,25 @@ export default defineConfig({
     timeout: 180_000,
   },
   projects: [
-    { name: "chromium", use: { ...devices["Desktop Chrome"] } },
-    { name: "firefox", use: { ...devices["Desktop Firefox"] } },
+    {
+      name: "chromium",
+      testIgnore: /responsive\.spec\.ts/,
+      use: { ...devices["Desktop Chrome"] },
+    },
+    {
+      name: "firefox",
+      testIgnore: /responsive\.spec\.ts/,
+      use: { ...devices["Desktop Firefox"] },
+    },
+    {
+      name: "webkit",
+      testIgnore: /responsive\.spec\.ts/,
+      use: { ...devices["Desktop Safari"] },
+    },
+    {
+      name: "mobile-chromium",
+      testMatch: /responsive\.spec\.ts/,
+      use: { ...devices["Pixel 5"] },
+    },
   ],
 });
diff --git a/public/CHANGELOG.md b/public/CHANGELOG.md
index 36e1840..98316f6 100644
--- a/public/CHANGELOG.md
+++ b/public/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 0.2.0 - 2026-09-02
+
+- Added exact atomic text-patch application/reversal against explicit local
+  snapshots with deterministic JSON/ZIP export.
+- Added layered ignore sources and tracked-state explanations, root
+  `.gitattributes` evaluation, and advisory release planning from Conventional
+  Commit headers.
+
 ## 0.1.0 - 2026-09-01
 
 - Added the initial local-first Git Tools workbench.
diff --git a/public/LICENSES/npm-runtime-licenses.txt b/public/LICENSES/npm-runtime-licenses.txt
index 45a7c95..d1e91be 100644
--- a/public/LICENSES/npm-runtime-licenses.txt
+++ b/public/LICENSES/npm-runtime-licenses.txt
@@ -1,5 +1,5 @@
 ==============================================================================
-@add-ideas/toolbox-contract@0.2.3
+@add-ideas/toolbox-contract@0.3.0
 Declared licence: Apache-2.0
 ==============================================================================
 --- LICENSE ---
@@ -198,7 +198,7 @@ Declared licence: Apache-2.0
 
 
 ==============================================================================
-@add-ideas/toolbox-helpers@0.1.0
+@add-ideas/toolbox-helpers@0.2.0
 Declared licence: GPL-3.0-or-later
 ==============================================================================
 --- LICENSE ---
@@ -879,7 +879,7 @@ Public License instead of this License.  But first, please read
 
 
 ==============================================================================
-@add-ideas/toolbox-shell-react@0.2.3
+@add-ideas/toolbox-shell-react@0.3.0
 Declared licence: Apache-2.0
 ==============================================================================
 --- LICENSE ---
@@ -1077,6 +1077,33 @@ Declared licence: Apache-2.0
       limitations under the License.
 
 
+==============================================================================
+fflate@0.8.2
+Declared licence: MIT
+==============================================================================
+--- LICENSE ---
+MIT License
+
+Copyright (c) 2023 Arjun Barrett
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
 ==============================================================================
 react@19.2.8
 Declared licence: MIT
diff --git a/public/README.md b/public/README.md
index 6336090..83a9074 100644
--- a/public/README.md
+++ b/public/README.md
@@ -8,12 +8,15 @@ Git Tools is a standalone local-first application in the [add·ideas Toolbox](ht
 
 - Unified and `git diff` patch parsing with file status, modes, renames, hunk counts, line numbers, statistics, binary markers, and diagnostics
 - Unified patch authoring from before/after text with bounded LCS, context selection, path safety, and missing-final-newline markers
-- Root `.gitignore` matching for comments, escapes, globstars, character classes, directory rules, negation, ordered explanations, and ignored-parent diagnostics
+- Exact, atomic text-patch application and reversal against an explicit JSON repository snapshot, with downloadable JSON or deterministic ZIP output and no working-tree access
+- Layered `.gitignore` matching for comments, escapes, globstars, character classes, directory rules, negation, global excludes, `.git/info/exclude`, parent-to-child nested files, explicit tracked state, winning-rule explanations, and ignored-parent diagnostics
+- Root `.gitattributes` evaluation with set/unset/value/unspecified states, last-match provenance, and directory-pattern diagnostics
 - Strict SemVer 2.0 precedence plus common exact, comparator, partial, wildcard, hyphen, tilde, caret, AND, and OR ranges
 - Conventional Commit builder and structural lint with breaking-change/footer diagnostics
 - Keep-a-Changelog heading/section normalization, stable ordering, and duplicate-entry removal
+- Advisory release planning from Conventional Commit headers: SemVer bump, grouped notes, tag name, invalid-input evidence, and review-only command sequence
 
-Patch and before/after inputs are capped at 4 MiB with additional file, line, hunk, and diff-matrix bounds. `.gitignore` evaluates one repository-root file only; it does not read nested ignore files, global excludes, index state, or submodules. No workspace or `.git` directory is accessed. See [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) and [docs/PRIVACY-SECURITY.md](docs/PRIVACY-SECURITY.md).
+Patch and before/after inputs are capped at 4 MiB with additional file, line, hunk, and diff-matrix bounds. Applied snapshots are text-only, exact-match, atomic, limited to 5,000 files/32 MiB, and never touch the working tree. Ignore inputs are an explicit local snapshot; command-line exclude rules and submodule repository boundaries are not modeled. Attribute macros and nested attribute files are not expanded. No workspace or `.git` directory is accessed. See [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) and [docs/PRIVACY-SECURITY.md](docs/PRIVACY-SECURITY.md).
 
 ## Development
 
@@ -27,7 +30,7 @@ npm run test:browser
 
 ## Release
 
-`npm run release:artifact` creates a deterministic `release/git-tools-0.1.0.zip` and checksum sidecar.
+`npm run release:artifact` creates a deterministic `release/git-tools-0.2.0.zip` and checksum sidecar.
 
 ## Licence
 
diff --git a/public/SOURCE.md b/public/SOURCE.md
index e3abdc4..d726cde 100644
--- a/public/SOURCE.md
+++ b/public/SOURCE.md
@@ -1,7 +1,7 @@
 # Corresponding source
 
-The corresponding source for Git Tools 0.1.0 is available at:
+The corresponding source for Git Tools 0.2.0 is available at:
 
-https://git.add-ideas.de/lotobo/git-tools/src/tag/v0.1.0
+https://git.add-ideas.de/lotobo/git-tools/src/tag/v0.2.0
 
 Build with Node.js 22, npm 11, `npm ci`, and `npm run release:artifact`.
diff --git a/public/THIRD_PARTY_NOTICES.md b/public/THIRD_PARTY_NOTICES.md
index 34e3918..d74e8c1 100644
--- a/public/THIRD_PARTY_NOTICES.md
+++ b/public/THIRD_PARTY_NOTICES.md
@@ -1,12 +1,12 @@
 # Third-party notices
 
-Git Tools 0.1.0 directly depends on these runtime packages:
+Git Tools 0.2.0 directly depends on these runtime packages:
 
 | Package                          | Pinned version | Declared licence |
 | -------------------------------- | -------------: | ---------------- |
-| `@add-ideas/toolbox-contract`    |          0.2.3 | Apache-2.0       |
-| `@add-ideas/toolbox-helpers`     |          0.1.0 | GPL-3.0-or-later |
-| `@add-ideas/toolbox-shell-react` |          0.2.3 | Apache-2.0       |
+| `@add-ideas/toolbox-contract`    |          0.3.0 | Apache-2.0       |
+| `@add-ideas/toolbox-helpers`     |          0.2.0 | GPL-3.0-or-later |
+| `@add-ideas/toolbox-shell-react` |          0.3.0 | Apache-2.0       |
 | `react`                          |         19.2.8 | MIT              |
 | `react-dom`                      |         19.2.8 | MIT              |
 
diff --git a/public/sw.js b/public/sw.js
index 160c63b..5bfae78 100644
--- a/public/sw.js
+++ b/public/sw.js
@@ -1,5 +1,5 @@
 const CACHE_PREFIX = "git-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(
diff --git a/public/toolbox-app.json b/public/toolbox-app.json
index 258735d..18dd994 100644
--- a/public/toolbox-app.json
+++ b/public/toolbox-app.json
@@ -3,7 +3,7 @@
   "schemaVersion": 1,
   "id": "de.add-ideas.git-tools",
   "name": "Git Tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Inspect and author Git interchange formats locally in the browser.",
   "entry": "./",
   "icon": "./favicon.svg",
@@ -29,9 +29,25 @@
     "crossOriginIsolated": false,
     "topLevelContext": false
   },
+  "io": {
+    "accepts": [
+      { "mediaType": "text/x-diff", "extensions": [".diff", ".patch"] },
+      {
+        "mediaType": "text/plain",
+        "extensions": [".gitignore", ".gitattributes", ".txt"]
+      },
+      { "mediaType": "application/json", "extensions": [".json"] }
+    ],
+    "produces": [
+      { "mediaType": "text/x-diff", "extensions": [".patch"] },
+      { "mediaType": "application/json", "extensions": [".json"] },
+      { "mediaType": "application/zip", "extensions": [".zip"] }
+    ]
+  },
+  "capabilities": { "required": [], "optional": [] },
   "privacy": {
     "processing": "local",
-    "fileUploads": true,
+    "fileUploads": false,
     "telemetry": false,
     "label": "Inputs stay in this browser; nothing is uploaded."
   },
diff --git a/src/components/HelpDialog.tsx b/src/components/HelpDialog.tsx
index e4887dc..d440743 100644
--- a/src/components/HelpDialog.tsx
+++ b/src/components/HelpDialog.tsx
@@ -31,7 +31,11 @@ export function HelpDialog({
           ×
         </button>
       </div>
-      <p>Inspect and author Git interchange formats locally in the browser.</p>
+      <p>
+        Inspect and author Git interchange formats locally in the browser, apply
+        or reverse text patches against explicit JSON snapshots, explain ignore
+        and attribute rules, and draft an advisory release plan.
+      </p>
       <p>
         All processing is performed in this browser. Imported data is treated as
         untrusted and bounded before parsing.
diff --git a/src/components/Workbench.tsx b/src/components/Workbench.tsx
index 9100b96..00b7d6b 100644
--- a/src/components/Workbench.tsx
+++ b/src/components/Workbench.tsx
@@ -4,15 +4,23 @@ import {
   CONVENTIONAL_TYPES,
   buildConventionalCommit,
   compareSemVer,
+  applyPatchToSnapshot,
+  createSnapshotZip,
   createUnifiedPatch,
+  evaluateGitAttributes,
   explainGitignore,
+  explainGitignoreWorkspace,
   lintConventionalCommit,
   normalizeChangelog,
   parseSemVer,
   parseUnifiedPatch,
+  planRelease,
   satisfiesSemVer,
+  type GitAttributeResult,
   type IgnoreResult,
+  type PatchApplicationResult,
   type PatchDocument,
+  type ReleasePlan,
 } from "../git/tools";
 
 const patchSample = `diff --git a/src/example.ts b/src/example.ts
@@ -62,7 +70,25 @@ const changelogSample = `# Changelog
 
 - Improve diagnostics
 `;
-type Tab = "patch" | "author" | "ignore" | "versions" | "commit" | "changelog";
+const attributeSample = `* text=auto
+*.sh text eol=lf
+*.bat text eol=crlf
+*.png -text binary
+docs/** linguist-documentation
+`;
+const releaseCommitSample = `feat(git): apply text patches to snapshots
+fix(ignore): explain nested precedence
+docs: clarify privacy boundary`;
+type Tab =
+  | "patch"
+  | "apply"
+  | "author"
+  | "ignore"
+  | "attributes"
+  | "versions"
+  | "commit"
+  | "release"
+  | "changelog";
 
 function download(value: string, filename: string, type = "text/plain") {
   triggerBlobDownload(
@@ -78,6 +104,13 @@ export function Workbench() {
   const [patch, setPatch] = useState<PatchDocument>(() =>
     parseUnifiedPatch(patchSample),
   );
+  const [snapshotSource, setSnapshotSource] = useState(() =>
+    JSON.stringify({ "src/example.ts": beforeSample }, null, 2),
+  );
+  const [reverseApply, setReverseApply] = useState(false);
+  const [applyResult, setApplyResult] = useState<PatchApplicationResult | null>(
+    null,
+  );
   const [before, setBefore] = useState(beforeSample);
   const [after, setAfter] = useState(afterSample);
   const [path, setPath] = useState("src/example.ts");
@@ -86,12 +119,25 @@ export function Workbench() {
     createUnifiedPatch(beforeSample, afterSample, "src/example.ts", 3),
   );
   const [ignoreSource, setIgnoreSource] = useState(ignoreSample);
+  const [globalExcludes, setGlobalExcludes] = useState("");
+  const [infoExcludes, setInfoExcludes] = useState("");
+  const [nestedIgnores, setNestedIgnores] = useState(
+    '{\n  "src/generated/.gitignore": "*\\n!README.md\\n"\n}',
+  );
+  const [trackedPaths, setTrackedPaths] = useState("");
   const [ignorePaths, setIgnorePaths] = useState(
     "dist/app.js\nnotes.log\n.keep.log\ncache/README.md\nsrc/main.ts",
   );
   const [ignoreResults, setIgnoreResults] = useState<IgnoreResult[]>(() =>
     explainGitignore(ignoreSample, ignorePaths.split("\n")),
   );
+  const [attributeSource, setAttributeSource] = useState(attributeSample);
+  const [attributePaths, setAttributePaths] = useState(
+    "src/main.ts\nscripts/release.sh\ndocs/guide.md\nassets/logo.png",
+  );
+  const [attributeResults, setAttributeResults] = useState<
+    GitAttributeResult[]
+  >(() => evaluateGitAttributes(attributeSample, attributePaths.split("\n")));
   const [versions, setVersions] = useState(
     "1.2.3\n1.3.0-beta.1\n1.3.0\n2.0.0\n0.9.8",
   );
@@ -110,6 +156,16 @@ export function Workbench() {
   const [normalized, setNormalized] = useState(() =>
     normalizeChangelog(changelogSample),
   );
+  const [releaseVersion, setReleaseVersion] = useState("0.2.0");
+  const [releaseDate, setReleaseDate] = useState("2026-09-01");
+  const [releaseCommits, setReleaseCommits] = useState(releaseCommitSample);
+  const [releasePlan, setReleasePlan] = useState<ReleasePlan>(() =>
+    planRelease({
+      currentVersion: "0.2.0",
+      commits: releaseCommitSample.split("\n"),
+      date: "2026-09-01",
+    }),
+  );
   const linted = useMemo(() => lintConventionalCommit(message), [message]);
   const versionRows = useMemo(
     () =>
@@ -166,10 +222,39 @@ export function Workbench() {
       );
     }
   };
+  const applyPatch = () => {
+    try {
+      const parsed = JSON.parse(snapshotSource) as unknown;
+      if (!parsed || typeof parsed !== "object" || Array.isArray(parsed))
+        throw new Error(
+          "The repository snapshot must be a JSON path-to-text object.",
+        );
+      const result = applyPatchToSnapshot(
+        patchSource,
+        parsed as Record<string, string>,
+        reverseApply,
+      );
+      setApplyResult(result);
+      setError("");
+    } catch (reason) {
+      setError(
+        reason instanceof Error ? reason.message : "Patch application failed.",
+      );
+    }
+  };
   const testIgnore = () => {
     try {
       setIgnoreResults(
-        explainGitignore(ignoreSource, ignorePaths.split(/\r?\n/u)),
+        explainGitignoreWorkspace(
+          {
+            root: ignoreSource,
+            globalExclude: globalExcludes,
+            infoExclude: infoExcludes,
+            nested: JSON.parse(nestedIgnores || "{}") as Record<string, string>,
+            tracked: trackedPaths.split(/\r?\n/u).filter(Boolean),
+          },
+          ignorePaths.split(/\r?\n/u),
+        ),
       );
       setError("");
     } catch (reason) {
@@ -178,6 +263,20 @@ export function Workbench() {
       );
     }
   };
+  const testAttributes = () => {
+    try {
+      setAttributeResults(
+        evaluateGitAttributes(attributeSource, attributePaths.split(/\r?\n/u)),
+      );
+      setError("");
+    } catch (reason) {
+      setError(
+        reason instanceof Error
+          ? reason.message
+          : ".gitattributes test failed.",
+      );
+    }
+  };
   const buildCommit = () => {
     try {
       setMessage(
@@ -210,6 +309,22 @@ export function Workbench() {
       );
     }
   };
+  const buildReleasePlan = () => {
+    try {
+      setReleasePlan(
+        planRelease({
+          currentVersion: releaseVersion,
+          commits: releaseCommits.split(/\r?\n/u),
+          date: releaseDate,
+        }),
+      );
+      setError("");
+    } catch (reason) {
+      setError(
+        reason instanceof Error ? reason.message : "Release planning failed.",
+      );
+    }
+  };
 
   return (
     <main className="workbench">
@@ -233,18 +348,20 @@ export function Workbench() {
         {(
           [
             "patch",
+            "apply",
             "author",
             "ignore",
+            "attributes",
             "versions",
             "commit",
+            "release",
             "changelog",
           ] as const
         ).map((value) => (
           <button
             key={value}
             type="button"
-            role="tab"
-            aria-selected={tab === value}
+            aria-pressed={tab === value}
             onClick={() => setTab(value)}
           >
             {value === "ignore"
@@ -284,7 +401,8 @@ export function Workbench() {
             </div>
             <p className="muted">
               The last valid inspection remains visible when later input is
-              malformed. Applying patches is intentionally out of scope.
+              malformed. Use the Apply tab for exact, text-only in-memory
+              application or reversal.
             </p>
           </section>
           <section className="panel workspace">
@@ -376,6 +494,117 @@ export function Workbench() {
         </div>
       )}
 
+      {tab === "apply" && (
+        <div className="split-layout">
+          <section className="panel workspace">
+            <div className="panel-heading">
+              <div>
+                <p className="eyebrow">Exact and atomic</p>
+                <h2>Apply patch to a text snapshot</h2>
+              </div>
+              <button type="button" className="primary" onClick={applyPatch}>
+                {reverseApply ? "Reverse patch" : "Apply patch"}
+              </button>
+            </div>
+            <p className="muted">
+              Supply a JSON object whose keys are repository-relative paths and
+              values are complete text files. Every hunk must match exactly;
+              binary patches, unsafe paths, partial and fuzzy application are
+              rejected, and failure leaves the last valid result unchanged.
+            </p>
+            <label className="field">
+              <span>Repository snapshot JSON</span>
+              <textarea
+                aria-label="Repository snapshot JSON"
+                value={snapshotSource}
+                onChange={(event) => setSnapshotSource(event.target.value)}
+                spellCheck={false}
+              />
+            </label>
+            <label className="check">
+              <input
+                type="checkbox"
+                checked={reverseApply}
+                onChange={(event) => setReverseApply(event.target.checked)}
+              />
+              Reverse old and new sides
+            </label>
+            <p className="muted">
+              The patch comes from the Patch tab. Nothing is written to your
+              working tree.
+            </p>
+          </section>
+          <section className="panel workspace">
+            <div className="panel-heading">
+              <div>
+                <p className="eyebrow">Result snapshot</p>
+                <h2>
+                  {applyResult
+                    ? `${applyResult.changed.length} path(s) changed`
+                    : "Not applied yet"}
+                </h2>
+              </div>
+            </div>
+            {applyResult ? (
+              <>
+                <ul className="steps">
+                  {applyResult.changed.map((item) => (
+                    <li key={`${item.oldPath}-${item.newPath}`}>
+                      <code>{item.newPath}</code>
+                      <span>
+                        {item.status}
+                        {item.oldPath !== item.newPath
+                          ? ` from ${item.oldPath}`
+                          : ""}
+                      </span>
+                      <small>{item.bytes} bytes</small>
+                    </li>
+                  ))}
+                </ul>
+                <textarea
+                  aria-label="Applied snapshot JSON"
+                  readOnly
+                  value={JSON.stringify(applyResult.files, null, 2)}
+                />
+                <div className="actions">
+                  <button
+                    type="button"
+                    onClick={() =>
+                      download(
+                        `${JSON.stringify(applyResult.files, null, 2)}\n`,
+                        "patched-snapshot.json",
+                        "application/json",
+                      )
+                    }
+                  >
+                    Download JSON
+                  </button>
+                  <button
+                    type="button"
+                    onClick={() => {
+                      const archive = createSnapshotZip(applyResult.files);
+                      triggerBlobDownload(
+                        new Blob([archive.slice().buffer as ArrayBuffer], {
+                          type: "application/zip",
+                        }),
+                        "patched-snapshot.zip",
+                      );
+                    }}
+                  >
+                    Download ZIP
+                  </button>
+                </div>
+              </>
+            ) : (
+              <p className="notice">
+                Apply or reverse the current patch to create a downloadable
+                in-memory result.
+              </p>
+            )}
+          </section>
+        </div>
+      )}
+
       {tab === "author" && (
         <section className="panel workspace">
           <div className="panel-heading">
@@ -477,6 +706,38 @@ export function Workbench() {
                 onChange={(event) => setIgnoreSource(event.target.value)}
               />
             </label>
+            <label className="field">
+              <span>Global excludes</span>
+              <textarea
+                aria-label="Global excludes"
+                value={globalExcludes}
+                onChange={(event) => setGlobalExcludes(event.target.value)}
+              />
+            </label>
+            <label className="field">
+              <span>.git/info/exclude</span>
+              <textarea
+                aria-label="Info excludes"
+                value={infoExcludes}
+                onChange={(event) => setInfoExcludes(event.target.value)}
+              />
+            </label>
+            <label className="field">
+              <span>Nested .gitignore files (JSON path → contents)</span>
+              <textarea
+                aria-label="Nested ignore files"
+                value={nestedIgnores}
+                onChange={(event) => setNestedIgnores(event.target.value)}
+              />
+            </label>
+            <label className="field">
+              <span>Already tracked paths, one per line</span>
+              <textarea
+                aria-label="Tracked paths"
+                value={trackedPaths}
+                onChange={(event) => setTrackedPaths(event.target.value)}
+              />
+            </label>
             <label className="field">
               <span>Paths, one per line; end directories with /</span>
               <textarea
@@ -501,9 +762,9 @@ export function Workbench() {
                   {result.matched.length > 0 && (
                     <ol>
                       {result.matched.map((match) => (
-                        <li key={match.line}>
-                          Line {match.line}: <code>{match.source}</code> →{" "}
-                          {match.outcome}
+                        <li key={`${match.origin ?? "root"}-${match.line}`}>
+                          {match.origin ?? ".gitignore"}:{match.line}:{" "}
+                          <code>{match.source}</code> → {match.outcome}
                         </li>
                       ))}
                     </ol>
@@ -512,14 +773,104 @@ export function Workbench() {
               ))}
             </div>
             <p className="muted">
-              This evaluates one repository-root ignore file. Nested .gitignore
-              files, global excludes, index state, and submodule boundaries are
-              not loaded.
+              Rules are evaluated from global excludes through .git/info/exclude
+              and parent-to-child .gitignore files. Explicitly tracked paths
+              remain included. Command-line excludes and submodule repository
+              boundaries are not modeled.
             </p>
           </section>
         </div>
       )}
 
+      {tab === "attributes" && (
+        <div className="split-layout">
+          <section className="panel workspace">
+            <div className="panel-heading">
+              <div>
+                <p className="eyebrow">Root .gitattributes</p>
+                <h2>Attribute rules and paths</h2>
+              </div>
+              <button
+                type="button"
+                className="primary"
+                onClick={testAttributes}
+              >
+                Evaluate attributes
+              </button>
+            </div>
+            <label className="field">
+              <span>.gitattributes contents</span>
+              <textarea
+                aria-label=".gitattributes source"
+                value={attributeSource}
+                onChange={(event) => setAttributeSource(event.target.value)}
+                spellCheck={false}
+              />
+            </label>
+            <label className="field">
+              <span>Repository-relative paths, one per line</span>
+              <textarea
+                aria-label="Attribute paths"
+                value={attributePaths}
+                onChange={(event) => setAttributePaths(event.target.value)}
+              />
+            </label>
+            <p className="muted">
+              Shows set, unset, value and unspecified states with the winning
+              source line. This bounded root-file tester does not expand custom
+              attribute macros.
+            </p>
+          </section>
+          <section className="panel workspace">
+            <div className="result-list">
+              {attributeResults.map((result) => (
+                <article key={result.path}>
+                  <header>
+                    <code>{result.path}</code>
+                    <strong>{result.attributes.length} attributes</strong>
+                  </header>
+                  {result.attributes.length ? (
+                    <table>
+                      <thead>
+                        <tr>
+                          <th>Attribute</th>
+                          <th>State</th>
+                          <th>Winning line</th>
+                        </tr>
+                      </thead>
+                      <tbody>
+                        {result.attributes.map((attribute) => (
+                          <tr key={attribute.name}>
+                            <td>
+                              <code>{attribute.name}</code>
+                            </td>
+                            <td>
+                              {attribute.state.kind === "value"
+                                ? `=${attribute.state.value}`
+                                : attribute.state.kind}
+                            </td>
+                            <td title={attribute.source}>{attribute.line}</td>
+                          </tr>
+                        ))}
+                      </tbody>
+                    </table>
+                  ) : (
+                    <p>No rule sets an attribute for this path.</p>
+                  )}
+                  {result.diagnostics.length > 0 && (
+                    <ul className="diagnostics">
+                      {result.diagnostics.map((diagnostic) => (
+                        <li key={diagnostic}>{diagnostic}</li>
+                      ))}
+                    </ul>
+                  )}
+                </article>
+              ))}
+            </div>
+          </section>
+        </div>
+      )}
+
       {tab === "versions" && (
         <div className="split-layout">
           <section className="panel workspace">
@@ -704,6 +1055,119 @@ export function Workbench() {
         </div>
       )}
 
+      {tab === "release" && (
+        <div className="split-layout">
+          <section className="panel workspace">
+            <div className="panel-heading">
+              <div>
+                <p className="eyebrow">Conventional-commit evidence</p>
+                <h2>Release planner</h2>
+              </div>
+              <button
+                type="button"
+                className="primary"
+                onClick={buildReleasePlan}
+              >
+                Build plan
+              </button>
+            </div>
+            <div className="form-grid">
+              <label className="field">
+                <span>Current version</span>
+                <input
+                  value={releaseVersion}
+                  onChange={(event) => setReleaseVersion(event.target.value)}
+                />
+              </label>
+              <label className="field">
+                <span>Release date</span>
+                <input
+                  type="date"
+                  value={releaseDate}
+                  onChange={(event) => setReleaseDate(event.target.value)}
+                />
+              </label>
+              <label className="field wide">
+                <span>Commit headers, one per line</span>
+                <textarea
+                  value={releaseCommits}
+                  onChange={(event) => setReleaseCommits(event.target.value)}
+                />
+              </label>
+            </div>
+            <p className="muted">
+              Breaking changes select major, features select minor, and fixes or
+              performance changes select patch. The plan is advisory: no Git or
+              package command is executed.
+            </p>
+          </section>
+          <section className="panel workspace">
+            <div className="facts">
+              <div>
+                <span>Bump</span>
+                <strong>{releasePlan.bump}</strong>
+              </div>
+              <div>
+                <span>Next version</span>
+                <strong>{releasePlan.nextVersion}</strong>
+              </div>
+              <div>
+                <span>Tag</span>
+                <strong>{releasePlan.tag}</strong>
+              </div>
+              <div>
+                <span>Valid commits</span>
+                <strong>{releasePlan.validCommits}</strong>
+              </div>
+            </div>
+            <label className="field">
+              <span>Generated release notes</span>
+              <textarea readOnly value={releasePlan.releaseNotes} />
+            </label>
+            <div className="actions">
+              <button
+                type="button"
+                onClick={() =>
+                  download(
+                    releasePlan.releaseNotes,
+                    `release-${releasePlan.nextVersion}.md`,
+                    "text/markdown",
+                  )
+                }
+              >
+                Download release notes
+              </button>
+            </div>
+            {releasePlan.commands.length > 0 && (
+              <div className="result">
+                <strong>Review-only command sequence</strong>
+                <ol className="command-list">
+                  {releasePlan.commands.map((command) => (
+                    <li key={command}>
+                      <code>{command}</code>
+                    </li>
+                  ))}
+                </ol>
+              </div>
+            )}
+            {releasePlan.ignoredCommits.length > 0 && (
+              <details>
+                <summary>
+                  {releasePlan.ignoredCommits.length} invalid commit(s) ignored
+                </summary>
+                <ul className="diagnostics">
+                  {releasePlan.ignoredCommits.map((commit) => (
+                    <li key={commit.source}>
+                      <code>{commit.source}</code>: {commit.reason}
+                    </li>
+                  ))}
+                </ul>
+              </details>
+            )}
+          </section>
+        </div>
+      )}
+
       {tab === "changelog" && (
         <div className="split-layout">
           <section className="panel workspace">
diff --git a/src/git/tools.ts b/src/git/tools.ts
index d1d2f62..1ece291 100644
--- a/src/git/tools.ts
+++ b/src/git/tools.ts
@@ -1,3 +1,5 @@
+import { strToU8, zipSync } from "fflate";
+
 export interface PatchLine {
   kind: "context" | "add" | "delete" | "meta";
   text: string;
@@ -440,9 +442,217 @@ export function createUnifiedPatch(
   return output.join("\n") + "\n";
 }
 
+export interface PatchApplicationResult {
+  files: Record<string, string>;
+  changed: Array<{
+    oldPath: string;
+    newPath: string;
+    status: PatchFile["status"];
+    bytes: number;
+  }>;
+}
+
+/**
+ * Applies a text-only patch to an explicit in-memory repository snapshot.
+ * Matching is exact and atomic: any mismatch rejects the whole operation.
+ */
+export function applyPatchToSnapshot(
+  patchInput: string | PatchDocument,
+  snapshot: Readonly<Record<string, string>>,
+  reverse = false,
+): PatchApplicationResult {
+  const parsed =
+    typeof patchInput === "string" ? parseUnifiedPatch(patchInput) : patchInput;
+  const document = reverse ? reversePatchDocument(parsed) : parsed;
+  const entries = Object.entries(snapshot);
+  if (entries.length > 5_000)
+    throw new Error("Repository snapshot exceeds the 5,000-file limit.");
+  let totalBytes = 0;
+  const files: Record<string, string> = {};
+  for (const [rawPath, contents] of entries) {
+    const path = safeRepositoryPath(rawPath);
+    if (typeof contents !== "string")
+      throw new Error(`Snapshot entry ${path} must contain text.`);
+    totalBytes += new TextEncoder().encode(contents).byteLength;
+    if (totalBytes > 32 * 1024 * 1024)
+      throw new Error("Repository snapshot exceeds the 32 MiB text limit.");
+    files[path] = contents;
+  }
+  const changed: PatchApplicationResult["changed"] = [];
+  const touched = new Set<string>();
+  for (const file of document.files) {
+    if (file.binary)
+      throw new Error(
+        `${file.newPath}: binary patches cannot be applied safely.`,
+      );
+    if (file.hunks.some((hunk) => !hunk.validCounts))
+      throw new Error(`${file.newPath}: a hunk has inconsistent line counts.`);
+    const oldPath = safeRepositoryPath(file.oldPath);
+    const newPath = safeRepositoryPath(file.newPath);
+    if (touched.has(oldPath) || touched.has(newPath))
+      throw new Error(
+        `${newPath}: the snapshot path is patched more than once.`,
+      );
+    touched.add(oldPath);
+    touched.add(newPath);
+    const before = files[oldPath];
+    if (file.status === "added") {
+      if (files[newPath] !== undefined)
+        throw new Error(`${newPath}: cannot add a path that already exists.`);
+    } else if (before === undefined) {
+      throw new Error(`${oldPath}: source path is missing from the snapshot.`);
+    }
+    if (
+      file.status === "renamed" &&
+      oldPath !== newPath &&
+      files[newPath] !== undefined
+    )
+      throw new Error(`${newPath}: rename target already exists.`);
+
+    const output = applyTextFilePatch(before ?? "", file);
+    if (file.status === "deleted") delete files[oldPath];
+    else {
+      if (oldPath !== newPath) delete files[oldPath];
+      files[newPath] = output;
+    }
+    changed.push({
+      oldPath,
+      newPath,
+      status: file.status,
+      bytes:
+        file.status === "deleted"
+          ? 0
+          : new TextEncoder().encode(output).byteLength,
+    });
+  }
+  return { files, changed };
+}
+
+function reversePatchDocument(document: PatchDocument): PatchDocument {
+  const files = document.files.map((file): PatchFile => ({
+    ...file,
+    oldPath: file.newPath,
+    newPath: file.oldPath,
+    status:
+      file.status === "added"
+        ? "deleted"
+        : file.status === "deleted"
+          ? "added"
+          : file.status,
+    oldMode: file.newMode,
+    newMode: file.oldMode,
+    added: file.deleted,
+    deleted: file.added,
+    hunks: file.hunks.map((hunk) => ({
+      ...hunk,
+      oldStart: hunk.newStart,
+      oldCount: hunk.newCount,
+      newStart: hunk.oldStart,
+      newCount: hunk.oldCount,
+      added: hunk.deleted,
+      deleted: hunk.added,
+      lines: hunk.lines.map((line) => ({
+        ...line,
+        kind:
+          line.kind === "add"
+            ? "delete"
+            : line.kind === "delete"
+              ? "add"
+              : line.kind,
+        oldLine: line.newLine,
+        newLine: line.oldLine,
+      })),
+    })),
+  }));
+  return {
+    files,
+    added: document.deleted,
+    deleted: document.added,
+    diagnostics: [...document.diagnostics],
+  };
+}
+
+function applyTextFilePatch(source: string, file: PatchFile): string {
+  const input = sourceLines(source);
+  const output: string[] = [];
+  let cursor = 0;
+  let finalNewline = input.finalNewline;
+  for (const hunk of file.hunks) {
+    const start = hunk.oldStart === 0 ? 0 : hunk.oldStart - 1;
+    if (start < cursor || start > input.lines.length)
+      throw new Error(
+        `${file.oldPath}: hunk ${hunk.header} is out of order or range.`,
+      );
+    output.push(...input.lines.slice(cursor, start));
+    cursor = start;
+    let previous: PatchLine | undefined;
+    for (const line of hunk.lines) {
+      if (line.kind === "meta") {
+        if (previous?.kind === "add" || previous?.kind === "context")
+          finalNewline = false;
+        previous = line;
+        continue;
+      }
+      if (line.kind === "add") output.push(line.text);
+      else {
+        if (input.lines[cursor] !== line.text)
+          throw new Error(
+            `${file.oldPath}: exact hunk match failed at source line ${cursor + 1}.`,
+          );
+        if (line.kind === "context") output.push(line.text);
+        cursor += 1;
+      }
+      previous = line;
+    }
+  }
+  output.push(...input.lines.slice(cursor));
+  if (file.status === "deleted") {
+    if (output.length !== 0)
+      throw new Error(`${file.oldPath}: deletion patch leaves text behind.`);
+    return "";
+  }
+  return output.join("\n") + (finalNewline ? "\n" : "");
+}
+
+function safeRepositoryPath(path: string): string {
+  const candidate = path.trim().replaceAll("\\", "/");
+  const normalized = normalizeRepositoryPath(path);
+  if (
+    !normalized ||
+    candidate.startsWith("/") ||
+    /^[A-Za-z]:\//u.test(candidate) ||
+    normalized.split("/").some((part) => part === ".." || part === ".") ||
+    normalized.includes("\0")
+  )
+    throw new Error(`Unsafe repository-relative path: ${path}`);
+  return normalized;
+}
+
+export function createSnapshotZip(
+  snapshot: Readonly<Record<string, string>>,
+): Uint8Array {
+  const entries: Record<string, [Uint8Array, { mtime: Date }]> = {};
+  let totalBytes = 0;
+  for (const [rawPath, contents] of Object.entries(snapshot).sort(
+    ([left], [right]) => left.localeCompare(right),
+  )) {
+    const path = safeRepositoryPath(rawPath);
+    if (typeof contents !== "string")
+      throw new Error(`${path}: ZIP snapshots accept text only.`);
+    const bytes = strToU8(contents);
+    totalBytes += bytes.byteLength;
+    if (totalBytes > 32 * 1024 * 1024)
+      throw new Error("ZIP input exceeds the 32 MiB limit.");
+    entries[path] = [bytes, { mtime: new Date("1980-01-01T00:00:00Z") }];
+  }
+  return zipSync(entries, { level: 6 });
+}
+
 export interface IgnoreRule {
   line: number;
   source: string;
+  origin?: string;
+  directory?: string;
   negated: boolean;
   directoryOnly: boolean;
   regex: RegExp;
@@ -450,7 +660,13 @@ export interface IgnoreRule {
 export interface IgnoreResult {
   path: string;
   ignored: boolean;
-  matched: { line: number; source: string; outcome: "ignore" | "include" }[];
+  tracked?: boolean;
+  matched: {
+    line: number;
+    source: string;
+    outcome: "ignore" | "include";
+    origin?: string;
+  }[];
   explanation: string;
 }
 function trimGitignoreLine(line: string): string {
@@ -480,10 +696,24 @@ function globRegex(pattern: string): string {
   }
   return output;
 }
-export function compileGitignore(source: string): IgnoreRule[] {
+function normalizeRepositoryPath(path: string): string {
+  return path
+    .trim()
+    .replaceAll("\\", "/")
+    .replace(/^\.\//u, "")
+    .replace(/^\/+|\/+$/gu, "");
+}
+
+export function compileGitignore(
+  source: string,
+  options: { directory?: string; origin?: string } = {},
+): IgnoreRule[] {
   if (source.length > 512 * 1024)
     throw new Error(".gitignore input exceeds 512 KiB.");
   const rules: IgnoreRule[] = [];
+  const directory = normalizeRepositoryPath(options.directory ?? "");
+  if (directory.split("/").includes(".."))
+    throw new Error("Ignore-file directory must be repository-relative.");
   for (const [index, original] of source
     .replaceAll("\r\n", "\n")
     .replaceAll("\r", "\n")
@@ -503,12 +733,20 @@ export function compileGitignore(source: string): IgnoreRule[] {
     if (anchored) line = line.slice(1);
     const hasSlash = line.includes("/");
     const body = globRegex(line);
-    const prefix = anchored || hasSlash ? "^" : "(?:^|.*/)";
+    const base = directory ? `${globRegex(directory)}/` : "";
+    const prefix =
+      anchored || hasSlash
+        ? `^${base}`
+        : directory
+          ? `^${base}(?:.*/)?`
+          : "(?:^|.*/)";
     const suffix = directoryOnly ? "(?:/.*)$" : "(?:/.*)?$";
     try {
       rules.push({
         line: index + 1,
         source: original,
+        ...(options.origin ? { origin: options.origin } : {}),
+        ...(directory ? { directory } : {}),
         negated,
         directoryOnly,
         regex: new RegExp(prefix + body + suffix, "u"),
@@ -536,6 +774,7 @@ function evaluateIgnore(
         line: rule.line,
         source: rule.source,
         outcome: ignored ? "ignore" : "include",
+        ...(rule.origin ? { origin: rule.origin } : {}),
       });
     }
   return { ignored, matched };
@@ -585,6 +824,245 @@ export function explainGitignore(
     });
 }
 
+export interface IgnoreWorkspace {
+  root: string;
+  nested?: Readonly<Record<string, string>>;
+  infoExclude?: string;
+  globalExclude?: string;
+  tracked?: readonly string[];
+}
+
+/** Evaluates Git's low-to-high exclude precedence for a repository snapshot. */
+export function explainGitignoreWorkspace(
+  workspace: IgnoreWorkspace,
+  paths: readonly string[],
+): IgnoreResult[] {
+  if (paths.length > 10_000)
+    throw new Error("Path test is limited to 10,000 entries.");
+  const nested = Object.entries(workspace.nested ?? {})
+    .map(([name, source]) => {
+      const normalized = normalizeRepositoryPath(name);
+      if (!normalized.endsWith(".gitignore"))
+        throw new Error(`Nested ignore source must end in .gitignore: ${name}`);
+      const slash = normalized.lastIndexOf("/");
+      const directory = slash < 0 ? "" : normalized.slice(0, slash);
+      return { name: normalized, directory, source };
+    })
+    .sort(
+      (left, right) =>
+        left.directory.split("/").filter(Boolean).length -
+          right.directory.split("/").filter(Boolean).length ||
+        left.name.localeCompare(right.name),
+    );
+  const rules = [
+    ...compileGitignore(workspace.globalExclude ?? "", {
+      origin: "global excludes",
+    }),
+    ...compileGitignore(workspace.infoExclude ?? "", {
+      origin: ".git/info/exclude",
+    }),
+    ...compileGitignore(workspace.root, { origin: ".gitignore" }),
+    ...nested.flatMap((item) =>
+      compileGitignore(item.source, {
+        directory: item.directory,
+        origin: item.name,
+      }),
+    ),
+  ];
+  const tracked = new Set(
+    (workspace.tracked ?? []).map(normalizeRepositoryPath).filter(Boolean),
+  );
+  return paths
+    .filter((value) => value.trim())
+    .map((raw) => {
+      const directory = raw.trim().endsWith("/");
+      const path = normalizeRepositoryPath(raw);
+      if (!path || path.split("/").includes(".."))
+        return {
+          path: raw,
+          ignored: false,
+          matched: [],
+          explanation: "Invalid repository-relative path; no rule evaluated.",
+        };
+      if (tracked.has(path))
+        return {
+          path: raw,
+          ignored: false,
+          tracked: true,
+          matched: evaluateIgnore(path + (directory ? "/" : ""), rules).matched,
+          explanation:
+            "The path is explicitly tracked; exclude rules affect only untracked files.",
+        };
+      const own = evaluateIgnore(path + (directory ? "/" : ""), rules);
+      const segments = path.split("/");
+      let blockedParent = "";
+      for (let index = 1; index < segments.length; index += 1) {
+        const parent = `${segments.slice(0, index).join("/")}/`;
+        if (evaluateIgnore(parent, rules).ignored) blockedParent = parent;
+      }
+      const ignored = own.ignored || Boolean(blockedParent);
+      const winner = own.matched.at(-1);
+      return {
+        path: raw,
+        ignored,
+        matched: own.matched,
+        explanation:
+          blockedParent && !own.ignored
+            ? `A negation cannot re-include the path while parent ${blockedParent} remains ignored.`
+            : winner
+              ? `Winning rule ${winner.origin ?? ".gitignore"}:${winner.line} ${ignored ? "ignores" : "includes"} the path.`
+              : "No exclude source matches; Git tracks the path by default.",
+      };
+    });
+}
+
+export type GitAttributeState =
+  | { kind: "set" }
+  | { kind: "unset" }
+  | { kind: "unspecified" }
+  | { kind: "value"; value: string };
+
+export interface GitAttributeResult {
+  path: string;
+  attributes: Array<{
+    name: string;
+    state: GitAttributeState;
+    line: number;
+    source: string;
+  }>;
+  diagnostics: string[];
+}
+
+interface GitAttributeRule {
+  line: number;
+  source: string;
+  regex: RegExp;
+  assignments: Array<{ name: string; state: GitAttributeState }>;
+}
+
+/** Evaluate a root .gitattributes snapshot with last-match-per-attribute semantics. */
+export function evaluateGitAttributes(
+  source: string,
+  paths: readonly string[],
+): GitAttributeResult[] {
+  if (source.length > 512 * 1024)
+    throw new Error(".gitattributes input exceeds 512 KiB.");
+  if (paths.length > 10_000)
+    throw new Error("Attribute testing is limited to 10,000 paths.");
+  const sharedDiagnostics: string[] = [];
+  const rules: GitAttributeRule[] = [];
+  for (const [index, original] of source
+    .replaceAll("\r\n", "\n")
+    .replaceAll("\r", "\n")
+    .split("\n")
+    .entries()) {
+    const tokens = tokenizeAttributeLine(original);
+    if (tokens.length === 0 || tokens[0]!.startsWith("#")) continue;
+    const pattern = tokens.shift()!;
+    if (pattern.startsWith("[attr]")) {
+      sharedDiagnostics.push(
+        `Line ${index + 1}: attribute macros are reported but not expanded by this bounded tester.`,
+      );
+      continue;
+    }
+    if (pattern.startsWith("!"))
+      throw new Error(
+        `Line ${index + 1}: negative attribute patterns are forbidden by Git.`,
+      );
+    if (pattern.endsWith("/"))
+      sharedDiagnostics.push(
+        `Line ${index + 1}: a trailing slash does not recursively match directory contents; use /** instead.`,
+      );
+    const assignments = tokens.map((token) =>
+      parseAttributeAssignment(token, index + 1),
+    );
+    if (assignments.length === 0) {
+      sharedDiagnostics.push(`Line ${index + 1}: pattern has no attributes.`);
+      continue;
+    }
+    const normalizedPattern = pattern.replace(/^\//u, "");
+    const body = globRegex(normalizedPattern);
+    const prefix = normalizedPattern.includes("/") ? "^" : "(?:^|.*/)";
+    try {
+      rules.push({
+        line: index + 1,
+        source: original,
+        regex: new RegExp(`${prefix}${body}$`, "u"),
+        assignments,
+      });
+    } catch {
+      throw new Error(`Line ${index + 1}: invalid attribute pattern.`);
+    }
+    if (rules.length > 10_000)
+      throw new Error(".gitattributes exceeds 10,000 active rules.");
+  }
+  return paths
+    .filter((path) => path.trim())
+    .map((rawPath): GitAttributeResult => {
+      const path = safeRepositoryPath(rawPath);
+      const attributes = new Map<
+        string,
+        GitAttributeResult["attributes"][number]
+      >();
+      for (const rule of rules) {
+        if (!rule.regex.test(path)) continue;
+        for (const assignment of rule.assignments)
+          attributes.set(assignment.name, {
+            ...assignment,
+            line: rule.line,
+            source: rule.source,
+          });
+      }
+      return {
+        path,
+        attributes: [...attributes.values()].sort((left, right) =>
+          left.name.localeCompare(right.name),
+        ),
+        diagnostics: [...sharedDiagnostics],
+      };
+    });
+}
+
+function tokenizeAttributeLine(line: string): string[] {
+  const output: string[] = [];
+  let token = "";
+  let escaped = false;
+  for (const character of line.trim()) {
+    if (escaped) {
+      token += character;
+      escaped = false;
+    } else if (character === "\\") escaped = true;
+    else if (/\s/u.test(character)) {
+      if (token) {
+        output.push(token);
+        token = "";
+      }
+    } else token += character;
+  }
+  if (escaped) token += "\\";
+  if (token) output.push(token);
+  return output;
+}
+
+function parseAttributeAssignment(
+  token: string,
+  line: number,
+): { name: string; state: GitAttributeState } {
+  const prefix = token[0];
+  const body = prefix === "-" || prefix === "!" ? token.slice(1) : token;
+  const equals = body.indexOf("=");
+  const name = equals < 0 ? body : body.slice(0, equals);
+  if (!/^[A-Za-z0-9][A-Za-z0-9_.-]*$/u.test(name))
+    throw new Error(
+      `Line ${line}: invalid attribute name ${name || "(empty)"}.`,
+    );
+  if (prefix === "-") return { name, state: { kind: "unset" } };
+  if (prefix === "!") return { name, state: { kind: "unspecified" } };
+  if (equals >= 0)
+    return { name, state: { kind: "value", value: body.slice(equals + 1) } };
+  return { name, state: { kind: "set" } };
+}
+
 export interface SemVer {
   major: number;
   minor: number;
@@ -1000,3 +1478,129 @@ export function normalizeChangelog(source: string): {
     diagnostics,
   };
 }
+
+export interface ReleasePlan {
+  currentVersion: string;
+  nextVersion: string;
+  bump: "none" | "patch" | "minor" | "major";
+  tag: string;
+  validCommits: number;
+  ignoredCommits: Array<{ source: string; reason: string }>;
+  groups: Array<{ heading: string; entries: string[] }>;
+  releaseNotes: string;
+  commands: string[];
+}
+
+/** Build a deterministic, advisory release plan without accessing a repository. */
+export function planRelease(input: {
+  currentVersion: string;
+  commits: readonly string[];
+  date?: string;
+  tagPrefix?: string;
+}): ReleasePlan {
+  const current = parseSemVer(input.currentVersion);
+  if (input.commits.length > 10_000)
+    throw new Error("Release planning is limited to 10,000 commit headers.");
+  const ignoredCommits: ReleasePlan["ignoredCommits"] = [];
+  const parsed: ConventionalCommit[] = [];
+  for (const source of input.commits) {
+    const trimmed = source.trim();
+    if (!trimmed) continue;
+    const commit = lintConventionalCommit(trimmed);
+    if (!commit.valid) {
+      ignoredCommits.push({
+        source: trimmed.slice(0, 300),
+        reason: commit.issues
+          .filter((issue) => issue.severity === "error")
+          .map((issue) => issue.message)
+          .join(" "),
+      });
+    } else parsed.push(commit);
+  }
+  const bump: ReleasePlan["bump"] = parsed.some((commit) => commit.breaking)
+    ? "major"
+    : parsed.some((commit) => commit.type === "feat")
+      ? "minor"
+      : parsed.some((commit) => ["fix", "perf"].includes(commit.type))
+        ? "patch"
+        : "none";
+  const next = {
+    major: current.major + (bump === "major" ? 1 : 0),
+    minor: bump === "major" ? 0 : current.minor + (bump === "minor" ? 1 : 0),
+    patch:
+      bump === "major" || bump === "minor"
+        ? 0
+        : current.patch + (bump === "patch" ? 1 : 0),
+  };
+  const nextVersion = `${next.major}.${next.minor}.${next.patch}`;
+  const headings: Record<string, string> = {
+    feat: "Added",
+    fix: "Fixed",
+    perf: "Changed",
+    security: "Security",
+    docs: "Documentation",
+    refactor: "Changed",
+    test: "Tests",
+    build: "Build",
+    ci: "Build",
+    chore: "Maintenance",
+    revert: "Reverted",
+    style: "Changed",
+  };
+  const grouped = new Map<string, string[]>();
+  for (const commit of parsed) {
+    const heading = headings[commit.type] ?? "Other";
+    const entry = `${commit.subject}${commit.scope ? ` (${commit.scope})` : ""}${commit.breaking ? " — BREAKING" : ""}`;
+    const entries = grouped.get(heading) ?? [];
+    if (!entries.some((item) => item.toLowerCase() === entry.toLowerCase()))
+      entries.push(entry);
+    grouped.set(heading, entries);
+  }
+  const groups = [...grouped.entries()]
+    .map(([heading, entries]) => ({ heading, entries: entries.sort() }))
+    .sort((left, right) => {
+      const leftIndex = SECTION_ORDER.indexOf(left.heading);
+      const rightIndex = SECTION_ORDER.indexOf(right.heading);
+      return (
+        (leftIndex < 0 ? 99 : leftIndex) - (rightIndex < 0 ? 99 : rightIndex) ||
+        left.heading.localeCompare(right.heading)
+      );
+    });
+  const date = input.date?.trim();
+  if (date && !/^\d{4}-\d{2}-\d{2}$/u.test(date))
+    throw new Error("Release date must use YYYY-MM-DD.");
+  const releaseNotes =
+    [
+      `## [${nextVersion}]${date ? ` - ${date}` : ""}`,
+      ...groups.flatMap((group) => [
+        "",
+        `### ${group.heading}`,
+        "",
+        ...group.entries.map((entry) => `- ${entry}`),
+      ]),
+    ].join("\n") + "\n";
+  const prefix = input.tagPrefix ?? "v";
+  if (!/^[A-Za-z0-9._/-]{0,32}$/u.test(prefix) || prefix.includes(".."))
+    throw new Error("Tag prefix contains unsafe characters.");
+  const tag = `${prefix}${nextVersion}`;
+  return {
+    currentVersion: current.raw,
+    nextVersion,
+    bump,
+    tag,
+    validCommits: parsed.length,
+    ignoredCommits,
+    groups,
+    releaseNotes,
+    commands:
+      bump === "none"
+        ? []
+        : [
+            `npm version ${nextVersion} --no-git-tag-version`,
+            `git add package.json package-lock.json CHANGELOG.md`,
+            `git commit -m "chore(release): ${nextVersion}"`,
+            `git tag -a ${tag} -m "${tag}"`,
+            `git push origin HEAD ${tag}`,
+          ],
+  };
+}
diff --git a/src/styles.css b/src/styles.css
index 47f6f81..f3fae28 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -161,7 +161,7 @@ textarea {
   overflow-x: auto;
   padding-bottom: 0.2rem;
 }
-.workspace-tabs button[aria-selected="true"] {
+.workspace-tabs button[aria-pressed="true"] {
   border-color: var(--toolbox-accent);
   background: var(--toolbox-accent);
   color: var(--toolbox-accent-contrast);
diff --git a/src/toolbox/manifest.source.json b/src/toolbox/manifest.source.json
index 258735d..735b9eb 100644
--- a/src/toolbox/manifest.source.json
+++ b/src/toolbox/manifest.source.json
@@ -3,7 +3,7 @@
   "schemaVersion": 1,
   "id": "de.add-ideas.git-tools",
   "name": "Git Tools",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Inspect and author Git interchange formats locally in the browser.",
   "entry": "./",
   "icon": "./favicon.svg",
@@ -29,9 +29,43 @@
     "crossOriginIsolated": false,
     "topLevelContext": false
   },
+  "io": {
+    "accepts": [
+      {
+        "mediaType": "text/x-diff",
+        "extensions": [".diff", ".patch"]
+      },
+      {
+        "mediaType": "text/plain",
+        "extensions": [".gitignore", ".gitattributes", ".txt"]
+      },
+      {
+        "mediaType": "application/json",
+        "extensions": [".json"]
+      }
+    ],
+    "produces": [
+      {
+        "mediaType": "text/x-diff",
+        "extensions": [".patch"]
+      },
+      {
+        "mediaType": "application/json",
+        "extensions": [".json"]
+      },
+      {
+        "mediaType": "application/zip",
+        "extensions": [".zip"]
+      }
+    ]
+  },
+  "capabilities": {
+    "required": [],
+    "optional": []
+  },
   "privacy": {
     "processing": "local",
-    "fileUploads": true,
+    "fileUploads": false,
     "telemetry": false,
     "label": "Inputs stay in this browser; nothing is uploaded."
   },
diff --git a/src/version.ts b/src/version.ts
index 76162f8..0ba6e37 100644
--- a/src/version.ts
+++ b/src/version.ts
@@ -1 +1 @@
-export const APP_VERSION = "0.1.0";
+export const APP_VERSION = "0.2.0";
diff --git a/tests/browser/app.spec.ts b/tests/browser/app.spec.ts
index 515ab8c..9d6e9ea 100644
--- a/tests/browser/app.spec.ts
+++ b/tests/browser/app.spec.ts
@@ -33,7 +33,7 @@ test("authors and re-inspects a patch without flashing state", async ({
 }) => {
   const external = await localOnly(page);
   await page.goto("/deep/nested/git/");
-  await page.getByRole("tab", { name: "Author" }).click();
+  await page.getByRole("button", { name: "Author" }).click();
   await page.getByLabel("After text").fill("alpha\nbeta\n");
   await page.getByRole("button", { name: "Generate patch" }).click();
   await expect(page.getByLabel("Generated patch")).toContainText("+alpha");
@@ -52,7 +52,7 @@ test("serves release identity and hardened headers", async ({ request }) => {
   const manifest = await request.get("/deep/nested/git/toolbox-app.json");
   await expect(manifest.json()).resolves.toMatchObject({
     id: "de.add-ideas.git-tools",
-    version: "0.1.0",
+    version: "0.2.0",
     entry: "./",
     privacy: { processing: "local", telemetry: false },
   });
diff --git a/tests/browser/responsive.spec.ts b/tests/browser/responsive.spec.ts
new file mode 100644
index 0000000..8ce862e
--- /dev/null
+++ b/tests/browser/responsive.spec.ts
@@ -0,0 +1,18 @@
+import { expect, test } from "@playwright/test";
+
+test("keeps the primary workspace inside a narrow viewport", async ({
+  page,
+}) => {
+  await page.goto("/deep/nested/git/");
+  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);
+});
diff --git a/tests/components/app.test.tsx b/tests/components/app.test.tsx
index f2f27e6..8061b36 100644
--- a/tests/components/app.test.tsx
+++ b/tests/components/app.test.tsx
@@ -14,7 +14,7 @@ describe("Git Tools", () => {
       await screen.findByRole("heading", { name: "Git Tools" }),
     ).toBeVisible();
     await userEvent.click(
-      await screen.findByRole("tab", { name: ".gitignore" }),
+      await screen.findByRole("button", { name: ".gitignore" }),
     );
     expect(screen.getAllByText(/Last matching rule/u).length).toBeGreaterThan(
       0,
diff --git a/tests/git/tools.test.ts b/tests/git/tools.test.ts
index ac06d67..35a4ec5 100644
--- a/tests/git/tools.test.ts
+++ b/tests/git/tools.test.ts
@@ -1,13 +1,18 @@
 import { describe, expect, it } from "vitest";
 import {
+  applyPatchToSnapshot,
   buildConventionalCommit,
   compareSemVer,
+  createSnapshotZip,
   createUnifiedPatch,
+  evaluateGitAttributes,
   explainGitignore,
+  explainGitignoreWorkspace,
   lintConventionalCommit,
   normalizeChangelog,
   parseSemVer,
   parseUnifiedPatch,
+  planRelease,
   satisfiesSemVer,
 } from "../../src/git/tools";
 
@@ -47,6 +52,33 @@ describe("Git interchange tools", () => {
     expect(parsed).toMatchObject({ added: 2, deleted: 1 });
   });
 
+  it("applies and reverses exact text patches atomically", () => {
+    const before = "a\nb\nc\n";
+    const after = "a\nB\nc\nd\n";
+    const patch = createUnifiedPatch(before, after, "src/file.txt", 1);
+    const applied = applyPatchToSnapshot(patch, {
+      "src/file.txt": before,
+      "README.md": "keep\n",
+    });
+    expect(applied.files).toEqual({
+      "src/file.txt": after,
+      "README.md": "keep\n",
+    });
+    expect(
+      applyPatchToSnapshot(patch, applied.files, true).files["src/file.txt"],
+    ).toBe(before);
+    expect(() =>
+      applyPatchToSnapshot(patch, { "src/file.txt": "different\n" }),
+    ).toThrow(/exact hunk match/u);
+  });
+
+  it("builds a deterministic text snapshot ZIP", () => {
+    const one = createSnapshotZip({ "b.txt": "B\n", "a.txt": "A\n" });
+    const two = createSnapshotZip({ "a.txt": "A\n", "b.txt": "B\n" });
+    expect([...one.slice(0, 4)]).toEqual([0x50, 0x4b, 0x03, 0x04]);
+    expect(one).toEqual(two);
+  });
+
   it("explains ordered ignore rules and blocked parents", () => {
     const source = `dist/\n*.log\n!keep.log\ncache/\n!cache/readme.md\n`;
     const results = explainGitignore(source, [
@@ -83,6 +115,76 @@ describe("Git interchange tools", () => {
     ]);
   });
 
+  it("evaluates global, info, nested, and tracked precedence with winning source", () => {
+    const results = explainGitignoreWorkspace(
+      {
+        globalExclude: "*.tmp\n*.log\n",
+        infoExclude: "private/\n",
+        root: "!keep.log\nsrc/*.tmp\n",
+        nested: {
+          "src/.gitignore": "!generated.tmp\n*.cache\n",
+          "src/deep/.gitignore": "!keep.cache\n",
+        },
+        tracked: ["private/tracked.txt"],
+      },
+      [
+        "debug.log",
+        "keep.log",
+        "src/generated.tmp",
+        "src/other.tmp",
+        "src/deep/drop.cache",
+        "src/deep/keep.cache",
+        "private/tracked.txt",
+      ],
+    );
+    expect(results.map((item) => item.ignored)).toEqual([
+      true,
+      false,
+      false,
+      true,
+      true,
+      false,
+      false,
+    ]);
+    expect(results[2]?.explanation).toContain("src/.gitignore:1");
+    expect(results[5]?.explanation).toContain("src/deep/.gitignore:1");
+    expect(results[6]).toMatchObject({ tracked: true });
+  });
+
+  it("evaluates .gitattributes states with per-attribute last matches", () => {
+    const [script, secret, image] = evaluateGitAttributes(
+      `* text=auto\n*.sh text eol=lf\nsecret.sh -text !eol\n*.png -text binary\n`,
+      ["scripts/build.sh", "secret.sh", "logo.png"],
+    );
+    expect(script?.attributes).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          name: "eol",
+          state: { kind: "value", value: "lf" },
+        }),
+        expect.objectContaining({ name: "text", state: { kind: "set" } }),
+      ]),
+    );
+    expect(image?.attributes).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({ name: "binary", state: { kind: "set" } }),
+        expect.objectContaining({ name: "text", state: { kind: "unset" } }),
+      ]),
+    );
+    expect(secret?.attributes).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          name: "eol",
+          state: { kind: "unspecified" },
+        }),
+      ]),
+    );
+    expect(
+      evaluateGitAttributes("docs/ text\n", ["docs/readme.md"])[0]
+        ?.diagnostics[0],
+    ).toContain("trailing slash");
+  });
+
   it("implements SemVer precedence and basic ranges", () => {
     expect(compareSemVer("1.0.0-alpha.1", "1.0.0-alpha.beta")).toBeLessThan(0);
     expect(compareSemVer("1.0.0+one", "1.0.0+two")).toBe(0);
@@ -123,4 +225,26 @@ describe("Git interchange tools", () => {
     );
     expect(result.output).toContain("## [1.0.0] - 2026-01-01");
   });
+
+  it("plans a release from valid conventional commit evidence", () => {
+    const plan = planRelease({
+      currentVersion: "1.4.2",
+      date: "2026-09-01",
+      commits: [
+        "fix(api): retain response headers",
+        "feat(ui): add timeline",
+        "bad commit",
+      ],
+    });
+    expect(plan).toMatchObject({
+      bump: "minor",
+      nextVersion: "1.5.0",
+      tag: "v1.5.0",
+      validCommits: 2,
+    });
+    expect(plan.releaseNotes).toContain("### Added");
+    expect(plan.releaseNotes).toContain("### Fixed");
+    expect(plan.ignoredCommits).toHaveLength(1);
+    expect(plan.commands.at(-1)).toContain("v1.5.0");
+  });
 });