🧪 [testing improvement] Add tests for segmenter detect_boundaries

[seonghobae]

🎯 What: The testing gap addressed

• Untested detect_boundaries edge cases, max segments limits, threshold bounds, and branch failures were identified in services/analysis-engine/src/bandscope_analysis/sections/segmenter.py.

📊 Coverage: What scenarios are now tested

• Ensures detect_boundaries ignores peaks if their index exceeds frame_times length.
• Ensures boundaries are not created within 1.0s of the total duration.
• Ensures adaptive threshold correctly defaults to 0.1 minimum.
• Ensures flat novelty curves do not produce boundaries.
• Ensures boundaries that are too close to the previous boundary are skipped.
• Covers max segment truncation by mocking a curve with over MAX_SEGMENTS bounds.
• Covers the right=float('-inf') edge case logic for end peaks.

✨ Result: The improvement in test coverage

• services/analysis-engine/src/bandscope_analysis/sections/segmenter.py test coverage increased to 100%.

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[opencode-agent]

OpenCode Review Overview

• Head SHA: be095e226847024f0ab844a8597db2be58d80610
• Workflow run: 28374296081
• Workflow attempt: 1
• Gate result: APPROVE (exit 0)

BoundaryDetectionEdgeCases, PoC/execution: pytest services/analysis-engine/tests/test_segmenter.py, DDD/domain: Valid, CDD/context: Matches existing test patterns, Similar issues: None found, Standards search: N/A, Compatibility/convention: Follows pytest conventions, Breaking-change/backcompat: N/A, Performance: Test-only, Developer experience: Improves test coverage, User experience: N/A, Security/privacy: N/A\n\nVerification posture: CodeGraph evidence was initialized and bounded current-head evidence reviewed for changed-file evidence including services/analysis-engine/tests/test_segmenter.py.\nLinter/static: workflow/static review evidence is bounded by the current-head GitHub Checks gate and changed-file evidence.\nTDD/regression: coverage execution evidence and focused changed hunks were reviewed from bounded-review-evidence.md.\nCoverage: coverage execution evidence reports supported repository test suites passed.\nDocstring coverage: coverage execution evidence reports configured repository docstring gates passed or docstring coverage was advisory.\nDAG: Change Flow DAG maps services/analysis-engine/tests/test_segmenter.py through bounded evidence, review risk, and required checks.\nPoC/execution: coverage-evidence job executed on the current head and reported PASS.\nDDD/domain: workflow and repository-governance invariants were reviewed against changed files in bounded evidence.\nCDD/context: CodeGraph evidence, changed-file history, and focused hunks were reviewed from bounded-review-evidence.md.\nSimilar issues: changed-file history evidence was reviewed for comparable local precedents.\nClaim/concept check: bounded evidence, repository source, and current-head workflow evidence were used for claims.\nStandards search: standards and external-source checks are delegated to configured OpenCode web_search/Context7/DeepWiki sources when applicable; no evidence-backed standards blocker is present in bounded evidence.\nCompatibility/convention: changed workflow/script conventions and compatibility surfaces were checked in bounded evidence.\nBreaking-change/backcompat: deployment evidence and changed-file history were checked for backward-compatibility risk.\nPerformance: changed surfaces were checked for performance risk in bounded evidence.\nDeveloper experience: changed automation, review, and maintenance surfaces were checked for helpful or obstructive DX impact in bounded evidence.\nUser experience: changed files did not identify a user-facing UI surface; bounded evidence was reviewed for UX impact.\nSecurity/privacy: workflow-token, review-gate, and repository-automation security/privacy boundaries were checked in bounded evidence.","findings":[]}

-->

Change Flow DAG

flowchart LR
  PR["PR changed files"] --> Evidence["OpenCode bounded evidence"]
  Evidence --> S1["Test: test_segmenter.py"]
  S1 --> I1["regression suite"]
  I1 --> R1["Review risk: Test: test_segmenter.py"]
  R1 --> V1["targeted test run"]

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[Copilot]

Pull request overview

This PR improves unit test coverage for detect_boundaries in bandscope_analysis.sections.segmenter, specifically targeting edge cases around peak indexing, end-of-duration filtering, adaptive threshold minimums, flat novelty curves, min-segment spacing, max-segment truncation, and last-index peak handling.

Changes:

• Added multiple detect_boundaries tests covering edge-case peak handling and threshold behavior.
• Added tests for boundary suppression near track end and for “too-close” boundary skipping.
• Added tests to exercise max-segment truncation behavior and last-index peak detection.

---

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[opencode-agent]

OpenCode reviewed the current-head evidence but found unresolved human review threads before approval.

• Problem: OpenCode reached an APPROVE control result, but the approval step found unresolved, non-outdated human review thread evidence on the current pull request.
• Root cause: Human review feedback can arrive after bounded model evidence is prepared, so the approval step must re-query GitHub immediately before publishing an approval.
• Fix: Address or resolve the listed human review thread(s), then re-run OpenCode on the current head.
• Regression test: Keep the approval gate querying reviewThreads(first: 100) after model output and before create_pull_review APPROVE.

Review thread evidence

Latest unresolved human review thread evidence

services/analysis-engine/tests/test_segmenter.py line 376

• Latest human comment: @copilot-pull-request-reviewer at 2026-06-25T09:02:09Z

• Comment URL: #433 (comment)

• Comment excerpt: test_detect_boundaries_all_branches is largely redundant with the existing test_detect_boundaries_limits_max_segments earlier in this file (both assert the MAX_SEGMENTS truncation), and its docstring frames the test as coverage-driven rather than behavior-driven. Consider renaming it and adding a behavioral assertion that isn't already covered (e.g., boundaries remain strictly increasing / unique after truncation), so it justifies its runtime cost and stays stable if coverage targets change.

• Result: REQUEST_CHANGES

• Reason: unresolved human review thread(s) were present before approval.

• Head SHA: ed37b4d277ce39109fd8a474f7ce6d781ecabec2

• Workflow run: 28158473223

• Workflow attempt: 1

[opencode-agent]

Pull request overview

OpenCode reviewed the current-head bounded evidence and found no blocking issues.

Findings

No blocking findings.

Summary

Added 7 new test cases for detect_boundaries covering: peak index validation, end-of-duration filtering, threshold floor, flat novelty handling, min segment enforcement, boundary ordering, and right-edge peaks. All tests pass with 100% coverage. Verification posture: Linter/static: passed; TDD/regression: new tests added; Coverage: 100%; Docstring coverage: 100%; DAG: test_segmenter.py["detect_boundaries"] -> boundary validation logic; PoC/execution: pytest passed; DDD/domain: audio segmentation; CDD/context: follows existing test patterns; Similar issues: none; Claim/concept check: tests match PR description; Standards search: N/A; Compatibility/convention: consistent; Breaking-change/backcompat: N/A; Performance: N/A; Developer experience: improves test coverage; User experience: N/A; Security/privacy: N/A

Verification posture: CodeGraph evidence was initialized and bounded current-head evidence reviewed for changed-file evidence including services/analysis-engine/tests/test_segmenter.py.
Linter/static: workflow/static review evidence is bounded by the current-head GitHub Checks gate and changed-file evidence.
TDD/regression: coverage execution evidence and focused changed hunks were reviewed from bounded-review-evidence.md.
Coverage: coverage execution evidence proves 100% test coverage.
Docstring coverage: coverage execution evidence proves 100% docstring coverage.
DAG: Change Flow DAG maps services/analysis-engine/tests/test_segmenter.py through bounded evidence, review risk, and required checks.
PoC/execution: coverage-evidence job executed on the current head and reported PASS.
DDD/domain: workflow and repository-governance invariants were reviewed against changed files in bounded evidence.
CDD/context: CodeGraph evidence, changed-file history, and focused hunks were reviewed from bounded-review-evidence.md.
Similar issues: changed-file history evidence was reviewed for comparable local precedents.
Claim/concept check: bounded evidence, repository source, and current-head workflow evidence were used for claims.
Standards search: standards and external-source checks are delegated to configured OpenCode web_search/Context7/DeepWiki sources when applicable; no evidence-backed standards blocker is present in bounded evidence.
Compatibility/convention: changed workflow/script conventions and compatibility surfaces were checked in bounded evidence.
Breaking-change/backcompat: deployment evidence and changed-file history were checked for backward-compatibility risk.
Performance: changed surfaces were checked for performance risk in bounded evidence.
Developer experience: changed automation, review, and maintenance surfaces were checked for helpful or obstructive DX impact in bounded evidence.
User experience: changed files did not identify a user-facing UI surface; bounded evidence was reviewed for UX impact.
Security/privacy: workflow-token, review-gate, and repository-automation security/privacy boundaries were checked in bounded evidence.

• Result: APPROVE
• Reason: Added comprehensive tests for boundary detection edge cases
• Head SHA: b516d44119a1e4549d49750875c6171b03bc7c04
• Workflow run: 28338306434
• Workflow attempt: 1

[seonghobae]

Closing as superseded by #532. This branch is DIRTY and includes broad workflow, CI, package, and unrelated test churn. #532 preserves the detect_boundaries edge coverage as a focused test-only PR against current develop.