Initial scaffold: action.yml, TypeScript source, ncc bundle

- action.yml with inputs (base-ref, head-ref, instructions, model, pr-strategy)
  and outputs (release-notes, release-notes-json, skipped-prs, uncertain-entries)
- src/inputs.ts: parse and validate action inputs
- src/prs.ts: find PRs via merge commits or GitHub API, fetch metadata
- src/prompt.ts: build Copilot CLI prompt from PR data + custom instructions
- src/copilot.ts: install and invoke Copilot CLI
- src/outputs.ts: parse JSON output, format markdown, set action outputs
- src/index.ts: orchestration pipeline
- dist/: bundled via @vercel/ncc for node20 runtime

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: tidy-dev

.gitignore

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+node_modules/
+lib/
+coverage/
+
+# Ignore compiled JS in src, but keep dist/
+src/**/*.js
+src/**/*.d.ts
+src/**/*.js.map

action.yml

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+name: 'Copilot Release Notes'
+description: 'AI-powered release notes generation from PRs between two refs, using GitHub Copilot CLI'
+author: 'GitHub'
+
+branding:
+  icon: 'file-text'
+  color: 'blue'
+
+inputs:
+  base-ref:
+    description: 'Tag, branch, or SHA to compare from (e.g., v3.5.6, release-3.5.6)'
+    required: true
+  head-ref:
+    description: 'Tag, branch, or SHA to compare to (defaults to HEAD)'
+    required: false
+    default: 'HEAD'
+  instructions:
+    description: 'Path to a markdown file with team-specific style guide for release notes'
+    required: false
+  model:
+    description: 'Model override for the Copilot CLI (e.g., gpt-4o, claude-sonnet-4)'
+    required: false
+  pr-strategy:
+    description: 'How to find PRs: merge-commits (default) or github-api'
+    required: false
+    default: 'merge-commits'
+
+outputs:
+  release-notes:
+    description: 'Generated release notes as formatted markdown text'
+  release-notes-json:
+    description: 'Structured JSON with per-entry data (tag, description, pr number, author)'
+  skipped-prs:
+    description: 'JSON array of PRs excluded from notes with reasons'
+  uncertain-entries:
+    description: 'JSON array of entries flagged for human review'
+
+runs:
+  using: 'node20'
+  main: 'dist/index.js'

dist/copilot.d.ts

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+export interface CopilotResult {
+    stdout: string;
+    exitCode: number;
+}
+/**
+ * Ensure the Copilot CLI is installed and available.
+ */
+export declare function ensureCopilotCLI(): Promise<string>;
+/**
+ * Run the Copilot CLI with the given prompt and return the result.
+ */
+export declare function runCopilot(copilotPath: string, prompt: string, model?: string): Promise<CopilotResult>;

dist/copilot.d.ts.map

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+export {};