Add test-coverage-detector workflow (detector/fixer pair for test-improver)

.github/workflows/gh-aw-test-coverage-detector.md

@@ -0,0 +1,158 @@
+---
+inlined-imports: true
+name: "Test Coverage Detector"
+description: "Find under-tested code paths and file a test coverage report"
+imports:
+  - gh-aw-fragments/elastic-tools.md
+  - gh-aw-fragments/runtime-setup.md
+  - gh-aw-fragments/formatting.md
+  - gh-aw-fragments/rigor.md
+  - gh-aw-fragments/mcp-pagination.md
+  - gh-aw-fragments/messages-footer.md
+  - gh-aw-fragments/safe-output-create-issue.md
+  - gh-aw-fragments/previous-findings.md
+  - gh-aw-fragments/pick-three-keep-one.md
+  - gh-aw-fragments/scheduled-audit.md
+  - gh-aw-fragments/network-ecosystems.md
+engine:
+  id: copilot
+  model: ${{ inputs.model }}
+on:
+  workflow_call:
+    inputs:
+      model:
+        description: "AI model to use"
+        type: string
+        required: false
+        default: "gpt-5.3-codex"
+      additional-instructions:
+        description: "Repo-specific instructions appended to the agent prompt"
+        type: string
+        required: false
+        default: ""
+      setup-commands:
+        description: "Shell commands to run before the agent starts (dependency install, build, etc.)"
+        type: string
+        required: false
+        default: ""
+      allowed-bot-users:
+        description: "Allowlisted bot actor usernames (comma-separated)"
+        type: string
+        required: false
+        default: "github-actions[bot]"
+      messages-footer:
+        description: "Footer appended to all agent comments and reviews"
+        type: string
+        required: false
+        default: ""
+      title-prefix:
+        description: "Title prefix for created issues (e.g. '[test-coverage]')"
+        type: string
+        required: false
+        default: "[test-coverage]"
+    secrets:
+      COPILOT_GITHUB_TOKEN:
+        required: true
+  roles: [admin, maintainer, write]
+  bots:
+    - "${{ inputs.allowed-bot-users }}"
+concurrency:
+  group: test-coverage-detector
+  cancel-in-progress: true
+permissions:
+  actions: read
+  contents: read
+  issues: read
+  pull-requests: read
+tools:
+  github:
+    toolsets: [repos, issues, pull_requests, search, labels, actions]
+  bash: true
+  web-fetch:
+strict: false
+safe-outputs:
+  activation-comments: false
+  noop:
+  create-issue:
+    max: 1
+    title-prefix: "${{ inputs.title-prefix }} "
+    close-older-issues: false
+    expires: 7d
+timeout-minutes: 90
+steps:
+  - name: Repo-specific setup
+    if: ${{ inputs.setup-commands != '' }}
+    env:
+      SETUP_COMMANDS: ${{ inputs.setup-commands }}
+    run: eval "$SETUP_COMMANDS"
+---
+
+Identify under-tested code paths that would benefit from focused tests and file a report issue with specific, actionable recommendations.
+
+**The bar is high: you must identify concrete, high-value test gaps before filing.** Most runs should end with `noop` — that means test coverage is adequate.
+
+### Data Gathering
+
+1. Determine required repo commands (lint/build/test) and how to run tests:
+   - Check README, CONTRIBUTING, DEVELOPING, Makefile, CI config, package.json, pyproject.toml, and similar files.
+2. Identify coverage tooling (nyc, jest --coverage, pytest --cov, go test -cover, etc.).
+   - If coverage is available and reasonably fast, run it to find low-coverage files.
+   - If coverage tooling is not available, use code analysis to identify untested code paths.
+3. Review recent changes:
+   - Run `git log --since="28 days ago" --stat` and identify recent changes without corresponding test updates.
+4. Use the **Pick Three, Keep One** pattern for the investigation phase: spawn 3 `general-purpose` sub-agents, each searching for test gaps from a different angle (e.g., one analyzing coverage reports, one reviewing recent commits for missing tests, one examining error paths and edge cases in public APIs). Include the repo conventions, coverage data, and the full "What to Look For" / "What to Skip" criteria in each sub-agent prompt. Each sub-agent should return its best candidate finding or recommend `noop`.
+
+### What to Look For
+
+- **Untested public APIs**: exported functions, CLI commands, API endpoints, or config parsing that have no or minimal test coverage.
+- **Error paths**: exception handling, validation failures, and edge cases that are not exercised by any test.
+- **Recent changes without tests**: code modified in the last 28 days where no corresponding test was added or updated.
+- **Critical business logic**: core algorithms, data transformations, or state machines with insufficient coverage.
+- **Trace to user-facing behavior.** For every candidate, answer: "What end-to-end user action would exercise this code path?" Only report gaps that map to a concrete user scenario.
+
+### What to Skip
+
+- Trivial getters, setters, or simple constructors — testing these adds maintenance burden without catching regressions.
+- Generated code, vendored dependencies, or third-party code.
+- Test files themselves.
+- Code paths that are adequately covered by integration or end-to-end tests, even if unit coverage is low.
+- Internal helper functions that are only reachable through already-tested public APIs.
+- Subjective "should have more tests" observations without a concrete user scenario.
+
+### Quality Gate — When to Noop
+
+Call `noop` if any of these are true:
+- Coverage tooling shows adequate coverage and no clear gaps in critical paths.
+- The only gaps found are trivial (getters, constructors, simple pass-through functions).
+- You cannot describe a concrete user scenario for any identified gap.
+- All gaps are already tracked in open issues.
+- The codebase has no testable code (e.g., pure configuration, documentation-only).
+
+### Issue Format
+
+**Issue title:** Test coverage gaps (date)
+
+**Issue body:**
+
+> ## Summary
+> - Coverage method: [tool used or manual analysis]
+> - Files analyzed: [count]
+> - Gaps identified: [count]
+>
+> ## Findings
+>
+> ### 1. [Brief description of the gap]
+> **File:** `path/to/file.ext`
+> **Function/Method:** `FuncName(...)`
+> **User scenario:** [Describe the real-world user action that exercises this code path]
+> **Why it matters:** [What regression could this catch? What could break?]
+> **Suggested test approach:** [Brief description of what a test should verify]
+>
+> ## Suggested Actions
+> - [ ] [Concrete action for each finding, e.g., "Add unit test for error handling in `ParseConfig` when config file is missing"]
+
+### Labeling
+
+- If the `test-coverage` label exists (check with `github-get_label`), include it in the `create_issue` call; otherwise, rely on the `${{ inputs.title-prefix }}` title prefix only.
+
+${{ inputs.additional-instructions }}

.github/workflows/smoke-test-install.yml

@@ -74,6 +74,7 @@ jobs:
             scheduled-fix
             small-problem-fixer
             stale-issues
+            test-coverage-detector
             test-improver
             text-auditor
             text-beautifier

.github/workflows/trigger-test-coverage-detector.yml

@@ -0,0 +1,19 @@
+# This file is auto-generated by scripts/dogfood.sh. Do not edit directly.
+# Edit gh-agent-workflows/test-coverage-detector/example.yml and run 'make compile' to regenerate.
+name: Trigger Test Coverage Detector
+on:
+  schedule:
+    - cron: "0 10 * * 1-5"
+  workflow_dispatch:
+
+permissions:
+  actions: read
+  contents: read
+  issues: write
+  pull-requests: read
+
+jobs:
+  run:
+    uses: ./.github/workflows/gh-aw-test-coverage-detector.lock.yml
+    secrets:
+      COPILOT_GITHUB_TOKEN: ${{ secrets.COPILOT_GITHUB_TOKEN }}

docs/workflows/gh-agent-workflows.md

@@ -26,7 +26,7 @@ Each workflow directory contains an `example.yml` starter and a README for trigg
 The quick setup script includes two opinionated sets:
 
 - **Starter repo operations set (default):** `pr-review`, `issue-triage`, `mention-in-issue`, `mention-in-pr`, `pr-actions-detective`
-- **Continuous improvement add-ons (`--continuous-improvement`):** `bug-hunter`, `bug-exterminator`, `code-simplifier`, `docs-patrol`, `newbie-contributor-patrol`, `small-problem-fixer`, `stale-issues`, `test-improver`, `breaking-change-detector`, `code-duplication-detector`, `update-pr-body`
+- **Continuous improvement add-ons (`--continuous-improvement`):** `bug-hunter`, `bug-exterminator`, `code-simplifier`, `docs-patrol`, `newbie-contributor-patrol`, `small-problem-fixer`, `stale-issues`, `test-coverage-detector`, `test-improver`, `breaking-change-detector`, `code-duplication-detector`, `update-pr-body`
 
 ## Available workflows
 
@@ -75,6 +75,7 @@ Many scheduled workflows follow a **detector / fixer** pattern: the detector fin
 | [Code Duplication Detector](gh-agent-workflows/code-duplication-detector.md) | [Code Duplication Fixer](gh-agent-workflows/code-duplication-fixer.md) | Duplicate / clustered code |
 | [Docs Patrol](gh-agent-workflows/docs-patrol.md) | — | Stale internal documentation |
 | [Newbie Contributor Patrol](gh-agent-workflows/newbie-contributor-patrol.md) | [Newbie Contributor Fixer](gh-agent-workflows/newbie-contributor-fixer.md) | Onboarding documentation gaps |
+| [Test Coverage Detector](gh-agent-workflows/test-coverage-detector.md) | [Test Improver](gh-agent-workflows/test-improver.md) | Test coverage gaps |
 | [Text Auditor](gh-agent-workflows/text-auditor.md) | [Text Beautifier](gh-agent-workflows/text-beautifier.md) | User-facing text quality |
 
 #### Standalone scheduled workflows
@@ -94,7 +95,6 @@ Many scheduled workflows follow a **detector / fixer** pattern: the detector fin
 | [Release Update Check](gh-agent-workflows/release-update.md) | Weekly schedule | Open a PR updating pinned ai-github-actions workflow SHAs and suggest workflow changes |
 | [Small Problem Fixer](gh-agent-workflows/small-problem-fixer.md) | Weekday schedule | Fix small, related issues and open a focused PR |
 | [Stale Issues](gh-agent-workflows/stale-issues.md) | Weekday schedule | Find resolved issues that can be closed |
-| [Test Improver](gh-agent-workflows/test-improver.md) | Weekly schedule | Add targeted tests and clean up redundant coverage |
 
 ### Elastic-specific workflows
 

docs/workflows/gh-agent-workflows/test-coverage.md

@@ -0,0 +1,121 @@
+# Test Coverage
+
+Find under-tested code and automatically add focused tests.
+
+**Test Coverage Detector** identifies code paths with no or minimal test coverage by running coverage tools (when available) and analyzing recent changes for missing tests. **Test Improver** adds focused tests that validate real behavior and cleans up redundant tests. Most runs of either workflow end with `noop`.
+
+## Quick install
+
+### Detector only
+
+Install the detector alone if you want to review test coverage reports before acting.
+
+```bash
+mkdir -p .github/workflows && curl -sL \
+  https://raw.githubusercontent.com/elastic/ai-github-actions/v0/gh-agent-workflows/test-coverage-detector/example.yml \
+  -o .github/workflows/test-coverage-detector.yml
+```
+
+### Full loop (detector + fixer)
+
+Install both for autonomous detection and test improvement.
+
+```bash
+mkdir -p .github/workflows && \
+curl -sL https://raw.githubusercontent.com/elastic/ai-github-actions/v0/gh-agent-workflows/test-coverage-detector/example.yml \
+  -o .github/workflows/test-coverage-detector.yml && \
+curl -sL https://raw.githubusercontent.com/elastic/ai-github-actions/v0/gh-agent-workflows/test-improver/example.yml \
+  -o .github/workflows/test-improver.yml
+```
+
+---
+
+## Test Coverage Detector
+
+Identifies code paths with no or minimal test coverage by running coverage tools (when available) and analyzing recent changes for missing tests. Files a report with specific, actionable recommendations for each gap — including the user scenario and suggested test approach.
+
+### Trigger
+
+| Event | Schedule |
+| --- | --- |
+| `schedule` | Weekdays |
+| `workflow_dispatch` | Manual |
+
+### Inputs
+
+| Input | Description | Default |
+| --- | --- | --- |
+| `additional-instructions` | Repo-specific instructions appended to the agent prompt | `""` |
+| `setup-commands` | Shell commands run before the agent starts | `""` |
+
+### Safe outputs
+
+- `create-issue` — file a test coverage report (max 1, auto-closes older reports)
+
+### Example workflow
+
+```yaml
+name: Test Coverage Detector
+on:
+  schedule:
+    - cron: "0 10 * * 1-5"
+  workflow_dispatch:
+
+permissions:
+  actions: read
+  contents: read
+  issues: write
+  pull-requests: read
+
+jobs:
+  run:
+    uses: elastic/ai-github-actions/.github/workflows/gh-aw-test-coverage-detector.lock.yml@v0
+    secrets:
+      COPILOT_GITHUB_TOKEN: ${{ secrets.COPILOT_GITHUB_TOKEN }}
+```
+
+---
+
+## Test Improver (fixer)
+
+Identifies code paths with no or minimal test coverage, adds focused tests that validate real behavior, and removes or consolidates clearly redundant tests. Only opens a PR for changes that would catch actual regressions — not trivial getters or incidental coverage.
+
+### Trigger
+
+| Event | Schedule |
+| --- | --- |
+| `schedule` | Weekly |
+| `workflow_dispatch` | Manual |
+
+### Inputs
+
+| Input | Description | Default |
+| --- | --- | --- |
+| `additional-instructions` | Repo-specific instructions appended to the agent prompt | `""` |
+| `setup-commands` | Shell commands run before the agent starts | `""` |
+
+### Safe outputs
+
+- `create-pull-request` — open a PR with test improvements
+
+### Example workflow
+
+```yaml
+name: Test Improver
+on:
+  schedule:
+    - cron: "0 9 * * 1"
+  workflow_dispatch:
+
+permissions:
+  actions: read
+  contents: write
+  issues: write
+  pull-requests: write
+
+jobs:
+  run:
+    uses: elastic/ai-github-actions/.github/workflows/gh-aw-test-improver.lock.yml@v0
+    secrets:
+      COPILOT_GITHUB_TOKEN: ${{ secrets.COPILOT_GITHUB_TOKEN }}
+```

gh-agent-workflows/README.md

@@ -31,10 +31,12 @@ Pre-built workflows with domain-specific prompts. These import the same base fra
 - [Product Manager Impersonator](product-manager-impersonator/) — propose well-researched new feature ideas
 - [Refactor Opportunist](refactor-opportunist/) — pitch proven refactors with partial implementations
 - [Stale Issues](stale-issues/) — detect stale issues
+- [Test Coverage Detector](test-coverage-detector/) — find under-tested code paths
 **Fixers** (create PRs):
 - [Bug Exterminator](bug-exterminator/) — fix bug-hunter issues
 - [Text Beautifier](text-beautifier/) — fix text-auditor issues
 - [Code Duplication Fixer](code-duplication-fixer/) — fix code-duplication-detector issues
+- [Test Improver](test-improver/) — fix test-coverage-detector issues
 
 **Event-driven** (comment on PRs):
 - [Dependency Review](dependency-review/) — analyze Dependabot/Renovate dependency update PRs across ecosystems (GitHub Actions, Go, npm, Python, Java, Buildkite)
@@ -75,6 +77,7 @@ workflows, or `--repo OWNER/REPO` when auto-detection is not available.
 - `refactor-opportunist`
 - `small-problem-fixer`
 - `stale-issues`
+- `test-coverage-detector`
 - `test-improver`
 - `breaking-change-detector`
 - `code-duplication-detector`

gh-agent-workflows/test-coverage-detector/README.md

@@ -0,0 +1,40 @@
+# Test Coverage Detector
+
+Find under-tested code paths and file a test coverage report.
+
+## How it works
+
+Identifies code paths with no or minimal test coverage by running coverage tools (when available) and analyzing recent changes for missing tests. Files a report with specific, actionable recommendations for each gap — including the user scenario and suggested test approach. The bar is high; most runs end with `noop`.
+
+## Quick Install
+
+```bash
+mkdir -p .github/workflows && curl -sL \
+  https://raw.githubusercontent.com/elastic/ai-github-actions/v0/gh-agent-workflows/test-coverage-detector/example.yml \
+  -o .github/workflows/test-coverage-detector.yml
+```
+
+See [example.yml](example.yml) for the full workflow file.
+
+## Trigger
+
+| Event | Schedule |
+| --- | --- |
+| `schedule` | Weekdays |
+| `workflow_dispatch` | Manual |
+
+## Inputs
+
+| Input | Description | Required | Default |
+| --- | --- | --- | --- |
+| `additional-instructions` | Repo-specific instructions appended to the agent prompt | No | `""` |
+| `setup-commands` | Shell commands run before the agent starts | No | `""` |
+| `allowed-bot-users` | Allowlisted bot actor usernames (comma-separated) | No | `github-actions[bot]` |
+
+## Safe Outputs
+
+- `create-issue` — file a test coverage report (max 1, auto-closes older reports)
+
+## Pairing
+
+This workflow is the read-only companion to [Test Improver](../test-improver/). The detector finds test coverage gaps; the improver adds the tests.