feat(action): add diff input and optional PR comment posting (#63)

- add `diff` input to pass `--diff <base>` to the CLI
- add `github-token` input for posting findings as PR comments
- stale comment cleanup: deletes previous react-doctor comments before posting
- tee output to file only when github-token is set (no change for existing users)
- add GitHub Actions section to README with input reference table

closes #61

Amp-Thread-ID: https://ampcode.com/threads/T-019c7ad9-c09d-713d-a08d-c699637a6846

Co-authored-by: Amp <amp@ampcode.com>

Author: bdsqqq

action.yml

@@ -14,6 +14,12 @@ inputs:
   project:
     description: "Workspace project(s) to scan (comma-separated)"
     required: false
+  diff:
+    description: "Base branch for diff mode (e.g. main). Only files changed vs this branch are scanned."
+    required: false
+  github-token:
+    description: "GitHub token for posting PR comments. When set on pull_request events, findings are posted as a PR comment."
+    required: false
   node-version:
     description: "Node.js version to use"
     default: "20"
@@ -35,11 +41,19 @@ runs:
         INPUT_DIRECTORY: ${{ inputs.directory }}
         INPUT_VERBOSE: ${{ inputs.verbose }}
         INPUT_PROJECT: ${{ inputs.project }}
+        INPUT_DIFF: ${{ inputs.diff }}
+        INPUT_GITHUB_TOKEN: ${{ inputs.github-token }}
       run: |
         FLAGS=""
         if [ "$INPUT_VERBOSE" = "true" ]; then FLAGS="$FLAGS --verbose"; fi
         if [ -n "$INPUT_PROJECT" ]; then FLAGS="$FLAGS --project $INPUT_PROJECT"; fi
-        npx -y react-doctor@latest "$INPUT_DIRECTORY" $FLAGS
+        if [ -n "$INPUT_DIFF" ]; then FLAGS="$FLAGS --diff $INPUT_DIFF"; fi
+
+        if [ -n "$INPUT_GITHUB_TOKEN" ]; then
+          npx -y react-doctor@latest "$INPUT_DIRECTORY" $FLAGS | tee /tmp/react-doctor-output.txt
+        else
+          npx -y react-doctor@latest "$INPUT_DIRECTORY" $FLAGS
+        fi
 
     - id: score
       shell: bash
@@ -48,3 +62,35 @@ runs:
       run: |
         SCORE=$(npx -y react-doctor@latest "$INPUT_DIRECTORY" --score 2>/dev/null || echo "")
         echo "score=$SCORE" >> "$GITHUB_OUTPUT"
+
+    - if: ${{ inputs.github-token != '' && github.event_name == 'pull_request' }}
+      uses: actions/github-script@v7
+      with:
+        github-token: ${{ inputs.github-token }}
+        script: |
+          const fs = require("fs");
+          const path = "/tmp/react-doctor-output.txt";
+          if (!fs.existsSync(path)) return;
+          const output = fs.readFileSync(path, "utf8").trim();
+          if (!output) return;
+
+          const marker = "<!-- react-doctor -->";
+          const body = `${marker}\n## 🩺 React Doctor\n\n\`\`\`\n${output}\n\`\`\``;
+
+          const { data: comments } = await github.rest.issues.listComments({
+            ...context.repo,
+            issue_number: context.issue.number,
+          });
+          const prev = comments.find((c) => c.body?.startsWith(marker));
+          if (prev) {
+            await github.rest.issues.deleteComment({
+              ...context.repo,
+              comment_id: prev.id,
+            });
+          }
+
+          await github.rest.issues.createComment({
+            ...context.repo,
+            issue_number: context.issue.number,
+            body,
+          });

packages/react-doctor/README.md

@@ -48,6 +48,29 @@ curl -fsSL https://react.doctor/install-skill.sh | bash
 
 Supports Cursor, Claude Code, Amp Code, Codex, Gemini CLI, OpenCode, Windsurf, and Antigravity.
 
+## GitHub Actions
+
+```yaml
+- uses: actions/checkout@v5
+  with:
+    fetch-depth: 0 # required for --diff
+- uses: millionco/react-doctor@main
+  with:
+    diff: main
+    github-token: ${{ secrets.GITHUB_TOKEN }}
+```
+
+| Input          | Default | Description                                                             |
+| -------------- | ------- | ----------------------------------------------------------------------- |
+| `directory`    | `.`     | Project directory to scan                                               |
+| `verbose`      | `true`  | Show file details per rule                                              |
+| `project`      |         | Workspace project(s) to scan (comma-separated)                         |
+| `diff`         |         | Base branch for diff mode. Only changed files are scanned              |
+| `github-token` |         | When set on `pull_request` events, posts findings as a PR comment      |
+| `node-version` | `20`    | Node.js version to use                                                 |
+
+The action outputs a `score` (0–100) you can use in subsequent steps.
+
 ## Options
 
 ```