feat: implement capacity estimate (workers → supportable jobs)

[lukas-frystak-sonarsource]

Summary

• Implements spec 031-capacity-estimate.md: an experimental --estimate-workers flag on analyze bgtasks (and run bgtasks for parity)
• Given a comma-separated list of worker counts, the estimator computes expected project-analysis throughput per hour (±20%) broken down by 8 size categories (XXS…XXXL)
• The estimate is log-only — the HTML report is byte-for-byte identical when the flag is omitted

Key changes

File	Change
internal/analyzer/bgtasks/estimate.go	New: pure 5-step estimation algorithm. Named constants for rounding granularity (0.1s), cost floor (0.1s), margin (20%), seconds-per-hour (3600).
internal/analyzer/bgtasks/estimate_test.go	New: 14 unit tests covering every acceptance criterion — happy path, ISSUE_SYNC exclusion, category shares summing to 1, mode floor, tie-breaking, duplicate/unsorted inputs, XXXL label, empty-category div-by-zero safety, proportional scaling.
internal/analyzer/bgtasks.go	AnalyzeBgTasks gains estimateWorkers []int; logCapacityEstimate is called after the report is written — report generation is never affected. DEBUG for intermediate arithmetic, INFO for headline results.
cmd/analyze.go	--estimate-workers IntSlice flag with >=1 validation; withEstimateWorkers option threads it through.
cmd/run.go	Same flag for parity.

Notable decisions

• EstimateCapacity is pure (no I/O, no globals); intermediate values are returned in the result struct and logged at the call site in logCapacityEstimate.
• XXXL upper bound uses ceiling division (maxObservedMs + 999) / 1000 so the label always shows a whole-second value ≥ the actual max.
• Mode tie-breaking picks the smaller rounded value for determinism, as specified.

Testing notes

• All 70+ existing tests continue to pass
• 14 new unit tests in estimate_test.go directly cover each acceptance criterion
• sonar analyze agentic --staged and golangci-lint run both report 0 issues
• Smoke test requiring a live SonarQube instance (sonar-insights -v analyze bgtasks --estimate-workers 4,8,16) was not run — no live instance available in CI; the flag wiring and logging logic are covered by the unit and integration tests in bgtasks_test.go

🤖 Generated with Claude Code

---

Summary by Gitar

• New specification:
  • Added specs/032-IMP-capacity-estimate-mean-and-demand.md to refine the capacity estimation logic, introducing mean-based costing and a demand-profile analysis.
• Refined estimation logic:
  • Updated internal/analyzer/bgtasks/estimate.go to use the mean of execution times as the representative cost, removing arbitrary ±20% margins and rounding-based mode selection.
  • Added DemandProfile calculation to compare throughput against peak and average analysis arrival rates.
• Updated logging:
  • Modified internal/analyzer/bgtasks.go to report per-worker verdict lines based on demand vs. capacity, replacing uncertainty margins with operational guidance.
• Regression testing:
  • Replaced existing mode-based unit tests in internal/analyzer/bgtasks/estimate_test.go with tests covering the new mean-based calculations, demand profiles, and verdict logic.

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[gitar-bot]

💡 Quality: Estimate integration tests assert only report creation

TestAnalyzeBgTasks_WithEstimateWorkers and TestAnalyzeBgTasks_EstimateSkipped_NoReport only assert that myreport.html is created — the same assertion already made by TestAnalyzeBgTasks_HappyPath. Neither test captures or inspects the logger output, so they don't actually verify that the capacity estimate ran, produced expected per-category throughput, applied the cost floor (the comment claims '20ms → floor applied'), excluded the ISSUE_SYNC task, or skipped gracefully with the expected reason. As written, these tests would still pass even if logCapacityEstimate did nothing. The pure algorithm is covered in estimate_test.go, so this is low impact, but capturing the debug logger output (e.g. into a bytes.Buffer via slog.NewTextHandler) and asserting on key lines would make these tests meaningfully exercise the wiring rather than duplicating the happy-path check.

Capture logger output and assert the estimate actually ran.:

var buf bytes.Buffer
debugLogger := slog.New(slog.NewTextHandler(&buf, &slog.HandlerOptions{Level: slog.LevelDebug}))
if err := AnalyzeBgTasks(dir, reportDir, "myreport", nil, nil, debugLogger, []int{4, 8}); err != nil {
	t.Fatalf("unexpected error: %v", err)
}
if !strings.Contains(buf.String(), "capacity estimate") {
	t.Errorf("expected capacity estimate to be logged, got:
%s", buf.String())
}

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[gitar-bot]

Code Review 👍 Approved with suggestions 4 resolved / 5 findings

Implements capacity estimation for background task workers using mean-based costing and demand profiles. Consider adding specific assertions for estimate output values in the integration tests to move beyond verifying report creation only.

💡 Quality: Estimate integration tests assert only report creation

📄 internal/analyzer/bgtasks_test.go:283-297

TestAnalyzeBgTasks_WithEstimateWorkers and TestAnalyzeBgTasks_EstimateSkipped_NoReport only assert that myreport.html is created — the same assertion already made by TestAnalyzeBgTasks_HappyPath. Neither test captures or inspects the logger output, so they don't actually verify that the capacity estimate ran, produced expected per-category throughput, applied the cost floor (the comment claims '20ms → floor applied'), excluded the ISSUE_SYNC task, or skipped gracefully with the expected reason. As written, these tests would still pass even if logCapacityEstimate did nothing. The pure algorithm is covered in estimate_test.go, so this is low impact, but capturing the debug logger output (e.g. into a bytes.Buffer via slog.NewTextHandler) and asserting on key lines would make these tests meaningfully exercise the wiring rather than duplicating the happy-path check.

Capture logger output and assert the estimate actually ran.

var buf bytes.Buffer
debugLogger := slog.New(slog.NewTextHandler(&buf, &slog.HandlerOptions{Level: slog.LevelDebug}))
if err := AnalyzeBgTasks(dir, reportDir, "myreport", nil, nil, debugLogger, []int{4, 8}); err != nil {
	t.Fatalf("unexpected error: %v", err)
}
if !strings.Contains(buf.String(), "capacity estimate") {
	t.Errorf("expected capacity estimate to be logged, got:
%s", buf.String())
}

✅ 4 resolved

✅ Quality: Step-5 arithmetic duplicated between estimator and logger

📄 internal/analyzer/bgtasks/estimate.go:258-272 📄 internal/analyzer/bgtasks.go:129-139 📄 internal/analyzer/bgtasks.go:157
computeWorkerEstimate (estimate.go) computes capacitySec, reportCapacitySec, and per-category catCapacitySec to derive jobs, while logCapacityEstimate (bgtasks.go:131-138) re-derives the exact same intermediate values independently for DEBUG logging using a separately-defined secondsPerHour constant in the analyzer package. If the estimation formula or the constant ever changes in one place, the DEBUG trace will silently diverge from the numbers actually used — which undermines the spec's stated goal that 'a reader must be able to reconstruct each result from the logs alone.' Consider returning these intermediate values in CategoryEstimate/WorkerEstimate (e.g. a CatCapacitySec field) and logging those, so there is a single source of truth.

✅ Quality: XXXL label is nonsensical when no task exceeds 180s

📄 internal/analyzer/bgtasks/estimate.go:196-201
In buildCategoryEstimates, the XXXL label uses upperBound = (maxObservedMs + 999) / 1000 where maxObservedMs is the maximum across ALL REPORT tasks (not just the XXXL bucket). When no REPORT task exceeds 180s, maxObservedMs can be small (e.g. 2000ms → upperBound=2), producing a backwards/misleading label like XXXL (180-2s). The bucket is empty in that case so it is skipped from INFO output, but it is still emitted at DEBUG for steps 3 and 4. Consider clamping the displayed upper bound to at least 180 (or labeling it > 180s when the bucket is empty / max is below 180).

✅ Quality: CLI validateEstimateWorkers has no unit test

📄 cmd/analyze.go:75-82 📄 cmd/run.go:58-61
validateEstimateWorkers enforces the >= 1 rule for --estimate-workers in both cmd/analyze.go and cmd/run.go, but the diff adds no test exercising it (the 14 new tests are all on the pure estimator). A regression that drops or weakens this validation (e.g. allowing 0, which would make capacitySec 0 and produce all-zero estimates) would go unnoticed. Consider a small table test for validateEstimateWorkers covering the <1, empty, and valid cases.

✅ Quality: Stray tags at end of spec file

📄 specs/032-IMP-capacity-estimate-mean-and-demand.md:342-343
The spec markdown file ends with two stray tags — </content> (line 342) and </invoke> (line 343) — that appear to be accidental artifacts left over from the file-creation tooling rather than intended content. They will render as literal text at the bottom of the rendered document and have no semantic meaning in the spec. Remove both lines so the file ends cleanly after line 341 (the × 24 note).

🤖 Prompt for agents

Code Review: Implements capacity estimation for background task workers using mean-based costing and demand profiles. Consider adding specific assertions for estimate output values in the integration tests to move beyond verifying report creation only.

1. 💡 Quality: Estimate integration tests assert only report creation
   Files: internal/analyzer/bgtasks_test.go:283-297

   `TestAnalyzeBgTasks_WithEstimateWorkers` and `TestAnalyzeBgTasks_EstimateSkipped_NoReport` only assert that `myreport.html` is created — the same assertion already made by `TestAnalyzeBgTasks_HappyPath`. Neither test captures or inspects the logger output, so they don't actually verify that the capacity estimate ran, produced expected per-category throughput, applied the cost floor (the comment claims '20ms → floor applied'), excluded the ISSUE_SYNC task, or skipped gracefully with the expected reason. As written, these tests would still pass even if `logCapacityEstimate` did nothing. The pure algorithm is covered in `estimate_test.go`, so this is low impact, but capturing the debug logger output (e.g. into a `bytes.Buffer` via `slog.NewTextHandler`) and asserting on key lines would make these tests meaningfully exercise the wiring rather than duplicating the happy-path check.

   Fix (Capture logger output and assert the estimate actually ran.):
   var buf bytes.Buffer
   debugLogger := slog.New(slog.NewTextHandler(&buf, &slog.HandlerOptions{Level: slog.LevelDebug}))
   if err := AnalyzeBgTasks(dir, reportDir, "myreport", nil, nil, debugLogger, []int{4, 8}); err != nil {
   	t.Fatalf("unexpected error: %v", err)
   }
   if !strings.Contains(buf.String(), "capacity estimate") {
   	t.Errorf("expected capacity estimate to be logged, got:
   %s", buf.String())
   }

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues
0 New dependency risks

Measures
0 Security Hotspots
95.4% Coverage on New Code
0.0% Duplication on New Code

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