Add Codecov coverage reporting

.github/workflows/ci.yml

@@ -37,6 +37,30 @@ jobs:
       - name: Run tests
         run: go test -race -cover ./...
 
+  coverage:
+    name: Coverage
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v7
+      - name: Set up Go
+        uses: actions/setup-go@v7
+        with:
+          go-version: 1.26.x
+          cache: true
+      - name: Generate coverage
+        run: go test -race -coverprofile=coverage.out -covermode=atomic ./...
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          use_oidc: true
+          files: ./coverage.out
+          disable_search: true
+          fail_ci_if_error: true
+
   lint:
     name: Lint
     runs-on: ubuntu-latest

README.md

@@ -1,6 +1,7 @@
 # Stacktrace
 
 [![CI](https://github.com/NdoleStudio/stacktrace/actions/workflows/ci.yml/badge.svg)](https://github.com/NdoleStudio/stacktrace/actions/workflows/ci.yml)
+[![codecov](https://codecov.io/gh/NdoleStudio/stacktrace/graph/badge.svg)](https://codecov.io/gh/NdoleStudio/stacktrace)
 [![Go Reference](https://pkg.go.dev/badge/github.com/NdoleStudio/stacktrace.svg)](https://pkg.go.dev/github.com/NdoleStudio/stacktrace)
 [![License](https://img.shields.io/github/license/NdoleStudio/stacktrace)](LICENSE)
 

docs/superpowers/plans/2026-07-19-codecov.md

@@ -0,0 +1,171 @@
+# Codecov Integration Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Upload one authoritative Go coverage report to Codecov and display its status in the README.
+
+**Architecture:** Add a dedicated Ubuntu/Go 1.26 coverage job without changing the compatibility matrix or lint job. Generate one atomic race-enabled profile, upload it through OIDC, and link the repository's Codecov badge from the README.
+
+**Tech Stack:** Go 1.18+, GitHub Actions, `codecov/codecov-action@v5`, GitHub OIDC
+
+## Global Constraints
+
+- Keep the existing test matrix and lint job unchanged.
+- Run the coverage job on `ubuntu-latest` with Go `1.26.x`.
+- Grant `contents: read` and `id-token: write` only to the coverage job.
+- Generate `coverage.out` with `go test -race -coverprofile=coverage.out -covermode=atomic ./...`.
+- Upload only `./coverage.out` through OIDC and fail CI when the upload fails.
+- Add no repository secret or Go dependency.
+- Keep README badge links scoped to `NdoleStudio/stacktrace`.
+
+---
+
+### Task 1: Add Codecov coverage reporting
+
+**Files:**
+- Modify: `.github/workflows/ci.yml`
+- Modify: `README.md`
+
+**Interfaces:**
+- Consumes: GitHub OIDC identity and Go's `coverage.out` profile.
+- Produces: One Codecov coverage upload per workflow run and a repository coverage badge.
+
+- [ ] **Step 1: Verify Codecov is not configured**
+
+Run:
+
+```bash
+rg -n "codecov|coverage.out|coverprofile" .github/workflows/ci.yml README.md
+```
+
+Expected: no output.
+
+- [ ] **Step 2: Add the dedicated coverage job**
+
+Insert this job between `test` and `lint`:
+
+```yaml
+  coverage:
+    name: Coverage
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v7
+      - name: Set up Go
+        uses: actions/setup-go@v7
+        with:
+          go-version: 1.26.x
+          cache: true
+      - name: Generate coverage
+        run: go test -race -coverprofile=coverage.out -covermode=atomic ./...
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          use_oidc: true
+          files: ./coverage.out
+          disable_search: true
+          fail_ci_if_error: true
+```
+
+- [ ] **Step 3: Add the README badge**
+
+Immediately after the CI badge, add:
+
+```markdown
+[![codecov](https://codecov.io/gh/NdoleStudio/stacktrace/graph/badge.svg)](https://codecov.io/gh/NdoleStudio/stacktrace)
+```
+
+- [ ] **Step 4: Verify the focused changes**
+
+Run:
+
+```bash
+rg -n "codecov|coverage.out|coverprofile|id-token" .github/workflows/ci.yml README.md
+git diff --check
+git diff -- .github/workflows/ci.yml README.md
+```
+
+Expected: one coverage job, one upload step, one badge, no whitespace errors,
+and no changes to the existing test matrix or lint job.
+
+- [ ] **Step 5: Commit the integration**
+
+```bash
+git add .github/workflows/ci.yml README.md
+git commit -m "ci: upload coverage to Codecov"
+```
+
+---
+
+### Task 2: Validate the branch
+
+**Files:**
+- Review: `.github/workflows/ci.yml`
+- Review: `README.md`
+
+**Interfaces:**
+- Consumes: The complete Codecov integration diff.
+- Produces: A clean branch ready to push.
+
+- [ ] **Step 1: Generate the coverage profile locally**
+
+Run:
+
+```bash
+go test -coverprofile=coverage.out -covermode=atomic ./...
+```
+
+Expected: both packages pass and `coverage.out` is created. The local
+Windows/ARM64 host omits `-race` because that platform does not support it;
+the Ubuntu CI coverage job runs the exact race-enabled command.
+
+- [ ] **Step 2: Remove the generated profile**
+
+Run:
+
+```bash
+Remove-Item -LiteralPath coverage.out
+git status --short
+```
+
+Expected: `coverage.out` is removed and no untracked coverage artifact remains.
+
+- [ ] **Step 3: Run repository checks**
+
+Run:
+
+```bash
+go test ./...
+go vet ./...
+golangci-lint fmt --diff
+golangci-lint run
+pre-commit run --all-files
+```
+
+Expected: every command passes.
+
+- [ ] **Step 4: Review the branch diff**
+
+Run:
+
+```bash
+git diff --check origin/main...HEAD
+git status --short
+git diff --stat origin/main...HEAD
+```
+
+Expected: no whitespace errors, a clean worktree, and only the design, plan,
+workflow, and README files in the branch.
+
+- [ ] **Step 5: Push the branch**
+
+Run:
+
+```bash
+git push -u origin copilot/add-codecov
+```
+
+Expected: the branch is published successfully.

docs/superpowers/specs/2026-07-19-codecov-design.md

@@ -0,0 +1,65 @@
+# Codecov Integration Design
+
+## Goal
+
+Publish repository coverage to Codecov from GitHub Actions and display the
+current coverage status in `README.md`.
+
+## CI Design
+
+Add one dedicated `coverage` job to `.github/workflows/ci.yml`. The job runs on
+Ubuntu with Go 1.26.x, independently of the existing nine-combination
+compatibility matrix. This avoids duplicate uploads while keeping the existing
+test job unchanged.
+
+Grant only this job:
+
+```yaml
+permissions:
+  contents: read
+  id-token: write
+```
+
+Generate an atomic race-enabled Go coverage profile:
+
+```bash
+go test -race -coverprofile=coverage.out -covermode=atomic ./...
+```
+
+Upload only `coverage.out` with `codecov/codecov-action@v5`. Use GitHub OIDC
+authentication instead of a repository secret, disable automatic report
+search, and fail the job if the upload fails:
+
+```yaml
+with:
+  use_oidc: true
+  files: ./coverage.out
+  disable_search: true
+  fail_ci_if_error: true
+```
+
+The repository must be enabled in Codecov for OIDC uploads and badge data.
+
+## README Design
+
+Add the Codecov badge immediately after the CI badge:
+
+```markdown
+[![codecov](https://codecov.io/gh/NdoleStudio/stacktrace/graph/badge.svg)](https://codecov.io/gh/NdoleStudio/stacktrace)
+```
+
+## File Impact
+
+Modify:
+
+- `.github/workflows/ci.yml`
+- `README.md`
+
+## Acceptance Checks
+
+1. The existing compatibility test matrix and lint job remain unchanged.
+2. The coverage job has the minimum permissions needed for checkout and OIDC.
+3. The coverage profile is explicit, atomic, race-enabled, and uploaded once.
+4. Codecov upload failures fail CI.
+5. The README badge targets `NdoleStudio/stacktrace`.
+6. Existing Go tests, vet, lint, formatting, and pre-commit checks pass.