feat: allow users to add their own review style prompts

.github/workflows/claude-review.yml

@@ -196,6 +196,8 @@ jobs:
       - name: Build review prompt
         id: prompt
         run: npx ts-node .tooling/scripts/build-review-prompt.ts
+        env:
+          PR_AUTHOR: ${{ github.event.pull_request.user.login }}
 
       - name: Cleanup previous AI review comments
         uses: actions/github-script@v7

docs/actions.md

@@ -304,6 +304,12 @@ prompt: |
   Ignore style and formatting issues entirely.
 ```
 
+**Personal Review Styles:**
+
+Individuals can customize the *tone* of reviews on their own PRs, across every
+repo that uses this workflow, without touching any repo's `.claude-review.yml`.
+See `review-styles/README.md` for setup and details.
+
 **Security Notes:**
 
 - Requires approval for external contributors to prevent prompt injection

review-styles/README.md

@@ -0,0 +1,54 @@
+# Personal review styles
+
+The [Claude AI PR review](../docs/actions.md#run-claude-reviewyml) uses one default
+prompt for everyone. If you want the review of *your* PRs to have a different tone
+or emphasis, regardless of which repo the PR is in, add a file here.
+
+## Setup
+
+Create `review-styles/<your-github-login>.md` (lowercase) in this repo, e.g.
+`review-styles/amonkhouse.md`. It's picked up automatically the next time a PR you
+author is reviewed, in any repo that uses this workflow. No other setup needed.
+
+## Format
+
+Optional YAML frontmatter, then your style content in plain prose or bullets:
+
+```markdown
+---
+mode: augment
+---
+Be blunt and terse. Skip the summary on small PRs.
+I care most about data-pipeline correctness and idempotency; flag anything
+that could double-write or silently drop rows. UK English.
+```
+
+If you omit the frontmatter, `mode` defaults to `augment`.
+
+## Modes
+
+- **`augment`** (default) - keeps the full default prompt (guardrails, review
+  format, priority emojis) and appends your content as a "Reviewer Style
+  Preferences" section, with a note that it wins on tone conflicts. Safest option;
+  right for most people who just want a different voice or emphasis.
+- **`replace_style`** - keeps the default guardrails and review format, but swaps
+  out the "How to write" tone guidance for your content. Use this if you have
+  strong, complete opinions on tone and don't want the default tone advice
+  competing with yours.
+- **`override`** - your content becomes the *entire* prompt. Nothing else is kept:
+  no false-positive guardrails, no required review format, no posting
+  instructions, unless you write them yourself. Only use this if you're
+  deliberately writing a full replacement prompt (mirrors the repo-level `prompt:`
+  field in `.claude-review.yml`, but scoped to you).
+
+## Precedence
+
+1. A repo's `.claude-review.yml` `prompt:` field (a full override for that repo)
+   always wins over your personal style - it's a deliberate repo-wide decision.
+2. Otherwise, your personal style is applied per its `mode`.
+3. A repo's `focus_areas`, `context`, and `ignore_paths` still apply in `augment`
+   and `replace_style` modes - scope stays with the repo, tone stays with you.
+   They do not apply under `override`, since there is no base prompt left to
+   append them to.
+
+See `amonkhouse.md` in this directory for a worked example.

review-styles/amonkhouse.md

@@ -0,0 +1,5 @@
+---
+mode: augment
+---
+UK English. Be direct: state the issue and the fix, then stop, no closing summary.
+I love emojis. Use more of them. Especially the frog.

scripts/build-review-prompt.test.ts

@@ -1,8 +1,14 @@
 import * as fs from "fs"
 import {
+  assemblePrompt,
   buildPrompt,
   DEFAULT_PROMPT,
+  HOW_TO_WRITE,
+  loadPersonalStyle,
   loadRepoConfig,
+  PROMPT_CLOSING,
+  PROMPT_HEADER,
+  parsePersonalStyle,
 } from "./build-review-prompt"
 
 jest.mock("fs")
@@ -104,6 +110,7 @@ prompt: |
 describe("buildPrompt", () => {
   beforeEach(() => {
     jest.clearAllMocks()
+    delete process.env.PR_AUTHOR
   })
 
   it("returns default prompt when no config exists", () => {
@@ -178,6 +185,223 @@ ignore_paths:
     expect(result).toContain("## Files to Skip")
     expect(result).toContain("- **/*.generated.ts")
   })
+
+  it("applies the PR author's personal style when PR_AUTHOR is set", () => {
+    process.env.PR_AUTHOR = "Amonkhouse"
+    mockFs.existsSync.mockImplementation(
+      p => typeof p === "string" && p.endsWith("amonkhouse.md")
+    )
+    mockFs.readFileSync.mockImplementation(p => {
+      if (typeof p === "string" && p.endsWith("amonkhouse.md")) {
+        return "Be blunt and terse."
+      }
+      throw new Error(`unexpected read: ${String(p)}`)
+    })
+
+    const result = buildPrompt()
+
+    expect(result).toContain("## Reviewer Style Preferences (amonkhouse)")
+    expect(result).toContain("Be blunt and terse.")
+    expect(result).toContain("### Summary") // default prompt structure retained
+  })
+
+  it("ignores personal style when no PR_AUTHOR is set", () => {
+    mockFs.existsSync.mockReturnValue(false)
+
+    const result = buildPrompt()
+
+    expect(result).not.toContain("Reviewer Style Preferences")
+    expect(result).toBe(DEFAULT_PROMPT)
+  })
+
+  it("repo-level prompt override still beats a personal style", () => {
+    process.env.PR_AUTHOR = "amonkhouse"
+    mockFs.existsSync.mockReturnValue(true)
+    mockFs.readFileSync.mockImplementation(p => {
+      if (typeof p === "string" && p.endsWith(".claude-review.yml")) {
+        return `
+prompt: |
+  You are a custom security reviewer.
+`
+      }
+      return "Be blunt and terse."
+    })
+
+    const result = buildPrompt()
+
+    expect(result).toContain("You are a custom security reviewer.")
+    expect(result).not.toContain("Reviewer Style Preferences")
+  })
+})
+
+describe("parsePersonalStyle", () => {
+  it("defaults to augment mode with no frontmatter", () => {
+    const result = parsePersonalStyle("amonkhouse", "Be blunt and terse.")
+
+    expect(result).toEqual({
+      login: "amonkhouse",
+      mode: "augment",
+      content: "Be blunt and terse.",
+    })
+  })
+
+  it("reads mode from frontmatter", () => {
+    const result = parsePersonalStyle(
+      "amonkhouse",
+      "---\nmode: replace_style\n---\nBe blunt and terse.\n"
+    )
+
+    expect(result.mode).toBe("replace_style")
+    expect(result.content).toBe("Be blunt and terse.")
+  })
+
+  it("falls back to augment and warns on an unknown mode", () => {
+    const consoleSpy = jest.spyOn(console, "error").mockImplementation()
+
+    const result = parsePersonalStyle(
+      "amonkhouse",
+      "---\nmode: nonsense\n---\nBe blunt and terse.\n"
+    )
+
+    expect(result.mode).toBe("augment")
+    expect(consoleSpy).toHaveBeenCalledWith(
+      expect.stringContaining("Unknown mode")
+    )
+    consoleSpy.mockRestore()
+  })
+
+  it("falls back to augment and warns on malformed frontmatter", () => {
+    const consoleSpy = jest.spyOn(console, "error").mockImplementation()
+
+    const result = parsePersonalStyle(
+      "amonkhouse",
+      "---\nmode: [unterminated\n---\nBe blunt and terse.\n"
+    )
+
+    expect(result.mode).toBe("augment")
+    expect(consoleSpy).toHaveBeenCalled()
+    consoleSpy.mockRestore()
+  })
+
+  it("supports override mode", () => {
+    const result = parsePersonalStyle(
+      "amonkhouse",
+      "---\nmode: override\n---\nYou are a custom reviewer.\n"
+    )
+
+    expect(result.mode).toBe("override")
+    expect(result.content).toBe("You are a custom reviewer.")
+  })
+})
+
+describe("loadPersonalStyle", () => {
+  beforeEach(() => {
+    jest.clearAllMocks()
+  })
+
+  it("returns null when no author is given", () => {
+    expect(loadPersonalStyle(undefined)).toBeNull()
+  })
+
+  it("returns null when no style file exists for the author", () => {
+    mockFs.existsSync.mockReturnValue(false)
+
+    expect(loadPersonalStyle("amonkhouse")).toBeNull()
+  })
+
+  it("lowercases the login when resolving the file path", () => {
+    mockFs.existsSync.mockImplementation(
+      p => typeof p === "string" && p.endsWith("review-styles/amonkhouse.md")
+    )
+    mockFs.readFileSync.mockReturnValue("Be blunt and terse.")
+
+    const result = loadPersonalStyle("AmonKHouse")
+
+    expect(result?.login).toBe("amonkhouse")
+    expect(result?.content).toBe("Be blunt and terse.")
+  })
+
+  it("returns null and logs a warning on read error", () => {
+    const consoleSpy = jest.spyOn(console, "error").mockImplementation()
+    mockFs.existsSync.mockReturnValue(true)
+    mockFs.readFileSync.mockImplementation(() => {
+      throw new Error("Read error")
+    })
+
+    const result = loadPersonalStyle("amonkhouse")
+
+    expect(result).toBeNull()
+    expect(consoleSpy).toHaveBeenCalledWith(
+      expect.stringContaining("Failed to read review-styles/amonkhouse.md")
+    )
+    consoleSpy.mockRestore()
+  })
+})
+
+describe("assemblePrompt", () => {
+  it("returns the default prompt when there is no repo config or personal style", () => {
+    expect(assemblePrompt(null, null)).toBe(DEFAULT_PROMPT)
+  })
+
+  it("augment mode keeps the default prompt and appends a style section", () => {
+    const result = assemblePrompt(null, {
+      login: "amonkhouse",
+      mode: "augment",
+      content: "Be blunt and terse.",
+    })
+
+    expect(result).toContain(DEFAULT_PROMPT)
+    expect(result).toContain("## Reviewer Style Preferences (amonkhouse)")
+    expect(result).toContain("Be blunt and terse.")
+    expect(result).toContain("prefer these")
+  })
+
+  it("replace_style mode keeps guardrails and format but swaps the tone block", () => {
+    const result = assemblePrompt(null, {
+      login: "amonkhouse",
+      mode: "replace_style",
+      content: "Be blunt and terse.",
+    })
+
+    expect(result).toContain(PROMPT_HEADER)
+    expect(result).toContain(PROMPT_CLOSING)
+    expect(result).toContain("## How to write\nBe blunt and terse.")
+    expect(result).not.toContain(HOW_TO_WRITE)
+    expect(result).not.toContain("Reviewer Style Preferences")
+  })
+
+  it("override mode returns only the personal content", () => {
+    const result = assemblePrompt(
+      { focus_areas: ["Watch for N+1 queries"] },
+      {
+        login: "amonkhouse",
+        mode: "override",
+        content: "You are a custom reviewer.",
+      }
+    )
+
+    expect(result).toBe("You are a custom reviewer.")
+  })
+
+  it("augment mode still applies repo focus areas and ignore paths", () => {
+    const result = assemblePrompt(
+      {
+        focus_areas: ["Watch for N+1 queries"],
+        ignore_paths: ["**/*.generated.ts"],
+      },
+      { login: "amonkhouse", mode: "augment", content: "Be blunt and terse." }
+    )
+
+    expect(result).toContain("## Additional Focus Areas")
+    expect(result).toContain("- Watch for N+1 queries")
+    expect(result).toContain("## Files to Skip")
+    expect(result).toContain("- **/*.generated.ts")
+    expect(result).toContain("## Reviewer Style Preferences (amonkhouse)")
+    // Style preferences should come after repo customizations
+    expect(result.indexOf("## Files to Skip")).toBeLessThan(
+      result.indexOf("## Reviewer Style Preferences")
+    )
+  })
 })
 
 describe("DEFAULT_PROMPT", () => {