Exclude test-app build tooling from coverage scope

[fpigeonjr]

Description

master has been red since #670 merged. The failure is the coverage-floor gate, not a test failure — all 151 spec files / 1377 tests pass:

  ✖ statements  88.57% (floor 88.73%)
  ✖ branches    78.57% (floor 78.65%)
  ✖ functions   85.74% (floor 85.90%)
  ✖ lines       88.55% (floor 88.72%)

Cause: a merge-order collision between #668 and #670. Both PRs were green on their own branches; master got the union.

• Fix inactive tab content rendering on top of active tab in sam-tabs-next #668 (tab overlap fix, merged 11:21) added the Playwright component-render harness, which introduced two build-tooling files at the test-app root: dedupe-packages.ts and esbuild/dedupe-angular-plugin.ts. Both run inside the bundler, so no spec can ever execute them — but Vitest's coverage.all walks the project and neither was in coverage.exclude, so they landed in the report at 0%: 14 statements, 4 branches, 4 functions, 14 lines of pure denominator.
• Lock coverage-floor gate at measured coverage (epic top-off) #670 (floor lock, merged 11:24) recorded the floor from coverage measured on a branch cut from 081088fe — i.e. before Fix inactive tab content rendering on top of active tab in sam-tabs-next #668 — so its denominator never saw those files.

Confirmed by diffing the two runs' test-app-coverage artifacts. The only files present in the failing report but absent from #670's green one are the four #668 additions; the two gallery components are 100% covered, the two tooling files are 0%.

	#670's PR run (green)	master (red)
statements	6655/7500 = 88.73%	6659/7518 = 88.57%

The change

One hunk in test-app/vitest.config.mts — two entries added to coverage.exclude:

"dedupe-packages.ts",
"esbuild/**",

This matches the rationale already documented in that config for src/main.ts, src/app/app.module.ts, src/environments/** and playwright.config.ts: keep harness/build scaffolding that has nothing to do with the library under test out of the denominator.

coverage-floor.json is deliberately untouched. Verified against the failing run's coverage artifact that dropping exactly these two files restores statements 88.73 / branches 78.65 / functions 85.90 / lines 88.72 — at or above every floor. Per the ratchet policy in AGENTS.md and scripts/check-coverage.mjs, lowering the floor to go green isn't an option anyway.

Follow-up worth tracking (not fixed here)

Coverage now sits exactly on the floor, with zero margin — the next non-library file added anywhere under test-app/ that isn't excluded will re-break master in precisely this way. Suggest tracking a real buffer (or a stricter coverage.include scoped to the library source) on #669.

Motivation and Context

Regression fix for the floor locked in #637 / #670, interacting with the harness added in #668.

Refs #637

Type of Change (Select One and Apply Label)

• Bug fix (non-breaking change which fixes an issue) → Apply bugfix label
• New feature (non-breaking change which adds functionality) → Apply enhancement label
• Breaking change (fix or feature that would cause existing functionality to change) → Apply breaking label
• Documentation / configuration update → Apply maintenance label

How to Test

1. npm ci && npm ci --prefix test-app
2. npm --prefix test-app test — full Vitest suite with coverage; writes test-app/coverage/coverage-summary.json.
3. npm run coverage:check — the gate that is currently failing on master.
4. To see the bug this fixes, revert just the config hunk and re-run: git stash push test-app/vitest.config.mts && npm --prefix test-app test && npm run coverage:check (expect all four metrics to fail by ~0.16pp), then git stash pop.

Expected result: step 2 reports 151 files / 1377 tests passed with statements 88.73% / branches 78.65% / functions 85.90% / lines 88.72%, and step 3 prints ✓ Coverage gate passed. with all four metrics at or above their floors. Step 4 reproduces the four ✖ lines from the failing master run.

Screenshots (if appropriate)

N/A — test-config-only change, no source, UI, or behavioral changes.

Checklist

• Branch name follows convention (e.g. gh-<number>-<slug>)
• PR title starts with a verb in the imperative mood
• I have self-reviewed my own code
• format:check passes (npm run format:check)
• lint passes (npm run lint) — 0 errors; root baseline gate passes at 1575 warnings (baseline 1619), test-app 0 errors / 4 pre-existing warnings
• build passes (cd test-app && npm run build)
• Tests pass and coverage is reported (cd test-app && npm test)
• If this change requires a documentation update, I have updated it accordingly
• If there are dependent changes, they have been merged and published in downstream modules

[Copilot]

Pull request overview

Updates the Vitest coverage configuration in test-app to exclude Playwright harness build-tooling files from the coverage denominator, restoring the intended “library code only” coverage scope and unblocking the coverage-floor.json gate on master.

Changes:

• Excludes test-app/dedupe-packages.ts from coverage reporting.
• Excludes everything under test-app/esbuild/** from coverage reporting.

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