test(backend): Go CI workflow + first unit-test layer (Track B Phase 1)

[ghchinoy]

What

Track B Phase 1 — the code-health vertical-slice gate. Adds the Go CI workflow and the first layer of backend unit tests. Every later Track B phase is validated against this gate.

• .github/workflows/go-test.yml — go build / go vet / go test on pull_request and push to main, mirroring sibling banana-weather (setup-go with go-version-file: backend/go.mod, cache-dependency-path: backend/go.sum, working-directory: backend).
• backend/storage_test.go
  • addWavHeader — asserts RIFF/WAVE/fmt /data markers at their offsets, fileSize == len(data)+36, correct little-endian byteRate/blockAlign/sampleRate/bitsPerSample fields, and that the raw PCM payload is preserved verbatim.
  • generateFilename — extension inference (wav/ogg/default mp3), take- prefix, uniqueness across 1000 calls.
• backend/generator_test.go
  • normalizeTags — each alias→canonical mapping, case-insensitivity, and no over-matching (already-canonical and non-tag substrings untouched). Written against behavior so it survives the planned Phase 3 regex hoist.

Why

Findings F6: the backend had no automated tests and no CI gate. This establishes both, table-driven and with no network / no GCP creds, matching the sibling repo's pattern.

Deferred

The JSON-repair path (generator.go handler: strip json fence → json.Unmarshal) is inline in a handler and not independently callable. Per the brief it is not refactored in this phase; it is deferred to the phase that touches that handler.

Scope

No production code or dependencies changed — test files + one workflow only. No model IDs / TTS logic touched (Track A boundary respected).

Local verification (cd backend)

$ go build ./...   # OK
$ go vet ./...     # OK
$ go test ./...
ok  	backend	0.020s

go test -v ./... — all subtests PASS:

• TestAddWavHeader (3 subtests)
• TestGenerateFilename (7 subtests, incl. uniqueness)
• TestNormalizeTags (17 subtests)

[ghchinoy]

PR #5 — Track B Phase 1 (CI workflow + Go unit tests) — Review

Executive Summary

Clean vertical-slice gate: one CI workflow mirroring banana-weather plus behavior-driven unit tests for addWavHeader, generateFilename, and normalizeTags. Risk: LOW. CI is green; no production code, deps, or model IDs touched.

Critical

None.

Required

None.

Nit / Optional

• Optional — JSON-repair path (design P1 bullet) is not tested. The PR correctly explains it is inline in a handler and not independently callable, and defers it to the phase that touches that handler. Reasonable; noting for tracking so the design's P1 list is fully satisfied when that handler is refactored.

FYI

• PR body says TestNormalizeTags has 17 subtests; the file defines 16. Cosmetic; no action.
• go-version-file: backend/go.mod / cache-dependency-path: backend/go.sum are correctly repo-root-relative (the defaults.run.working-directory: backend applies only to run: steps, not the setup-go action inputs) — verified correct.

Positive Feedback

• Tests are genuinely non-tautological: expected values are recomputed from inputs (byteRate, blockAlign, fileSize=dataLen+36, marker offsets) and checked against the real functions — a regression in addWavHeader would be caught.
• normalizeTags test asserts observable behavior only (input→output over all 7 alias→canonical mappings, case-insensitivity, no over-matching on [sighs]/bare sigh), so it survives the Phase 3 regex hoist as intended. All 7 mappings match production exactly.
• generateFilename covers MIME inference (wav/x-wav/ogg/default mp3), take- prefix, and a 1000-iteration uniqueness check.

Test Coverage

New code paths (all three target helpers) covered. Only gap is the deferred JSON-repair path, documented and justified.

Backward Compatibility

N/A — test files + one workflow only; no wire format, no production code.

Final Verdict

APPROVE

Gates run: verified PR diff via gh pr diff; gh pr checks → test: pass (1m31s) (go build/vet/test green in CI). Cross-checked each assertion against the actual generator.go/storage.go sources on the head ref via the GitHub API (non-destructive; no checkout of the shared tree). Could not run the Go toolchain locally — no checkout permitted per brief; CI covers the build/vet/test gate.