fix(vscode): correct Cobertura merge arithmetic, MSTest assembly discovery, and closure-filter documentation (#733)

docs/features/active/2026-09-02-coverage-cobertura-mstest-powershell-tooling-defects-733/evidence/baseline/branch-commit-baseline.2026-09-02T21-50.md

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+# Phase 0 — Branch and Commit Baseline (P0-T3)
+
+Timestamp: 2026-09-02T21-50
+
+Task: [P0-T3]
+
+## Command 1
+
+Command: git rev-parse --abbrev-ref HEAD
+EXIT_CODE: 0
+
+Branch: bug/coverage-cobertura-mstest-powershell-tooling-defects-733
+
+## Command 2
+
+Command: git rev-parse HEAD
+EXIT_CODE: 0
+
+HEAD SHA: 940c2d00db999c6c307cb18fd5369bd5985381f4
+
+This SHA is recorded as a statement of the state observed at Phase 0. It is a record of
+state only; no later task in this plan asserts against it.
+
+## Command 3
+
+Command: git status --porcelain
+EXIT_CODE: 0
+
+Verbatim output:
+
+```
+ M .claude/agent-memory/orchestrator/MEMORY.md
+ M docs/features/active/2026-09-02-coverage-cobertura-mstest-powershell-tooling-defects-733/plan.2026-09-02T12-01.md
+?? .claude/agent-memory/orchestrator/powershell-change-budget-override-for-consolidated-issue.md
+?? .claude/agent-memory/orchestrator/pwsh-blanket-blocked-in-isolated-worktree-for-orchestrator.md
+?? docs/features/active/2026-09-02-coverage-cobertura-mstest-powershell-tooling-defects-733/evidence/
+```
+
+## Output Summary
+
+Branch and HEAD SHA captured. Three of the five reported paths are pre-existing dirty state
+under .claude/agent-memory/orchestrator/ that this plan did not create and must not touch or
+stage. The remaining two are this plan's own artifacts: the plan file (P0-T1's checkbox
+update) and the newly created FEATURE/evidence/ tree.
+
+Note for P5-T9 (AC4, outside this delegation's scope): the three
+.claude/agent-memory/orchestrator/ paths pre-date this plan's first task and fall outside the
+three allowed prefixes P5-T9 enumerates. Their presence at Phase 0 is recorded here so that
+the AC4 gate can distinguish pre-existing worktree state from a stray write made by this plan.

docs/features/active/2026-09-02-coverage-cobertura-mstest-powershell-tooling-defects-733/evidence/baseline/file-size-headroom.2026-09-02T21-50.md

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+# Phase 0 — File Size and Headroom Baseline (P0-T4)
+
+Timestamp: 2026-09-02T21-50
+
+Task: [P0-T4]
+
+Ceiling: 500 lines per file, per the File Size Limit section of
+.claude/rules/general-code-change.md and the Coding Standards section of
+.claude/rules/powershell.md.
+
+## Measurement Method
+
+Two commands were run per file:
+
+Command: `wc -l < <file>`
+Command: `tr -cd '\n' < <file> | wc -c` and `tail -c 1 <file> | od -An -c`
+EXIT_CODE: 0 (both)
+
+Every one of the seven files ends with a trailing newline byte. For a file that ends with a
+newline, the newline count equals the number of content lines, so the figures below are
+content-line counts. A line-numbered viewer that renders a phantom empty line after the final
+newline reports one more than this for the same file; that accounts for the plan's own
+492-line figure for Invoke-MSTestWithCoverage.Helpers.ps1 against the 491 measured here. The
+two figures describe the same file under two counting conventions and do not conflict. The
+smaller headroom (the plan's, treating the file as 492 lines) is carried forward below as the
+conservative value.
+
+## Measured Line Counts and Headroom
+
+| File | Lines | Headroom (500 - lines) |
+|---|---|---|
+| scripts/vscode/Invoke-MSTestWithCoverage.Helpers.ps1 | 491 | 9 |
+| scripts/vscode/Invoke-MSTestWithCoverage.ps1 | 349 | 151 |
+| scripts/vscode/Invoke-MSTestWithCoverage.ClosureFilter.ps1 | 389 | 111 |
+| scripts/vscode/Invoke-MSTest.ps1 | 131 | 369 |
+| tests/scripts/vscode/Invoke-MSTestWithCoverage.Helpers.Tests.ps1 | 498 | 2 |
+| tests/scripts/vscode/Invoke-MSTestWithCoverage.ClosureFilter.Tests.ps1 | 443 | 57 |
+| tests/scripts/vscode/Invoke-MSTest.RunSettings.Tests.ps1 | 459 | 41 |
+
+## Explicit Flag — Invoke-MSTestWithCoverage.Helpers.ps1
+
+scripts/vscode/Invoke-MSTestWithCoverage.Helpers.ps1 is at or within 9 lines of the 500-line
+ceiling: 491 lines measured here, 492 lines as measured during the planning pass, leaving 9
+lines of headroom on the measured figure and only 8 lines on the planning-pass figure. Either
+way there is not enough room to add a new function with its comment-based help inline.
+
+Phase 1 addresses this by extracting the new `Get-CoberturaPackageLineSummary` helper into a
+new sibling production file, scripts/vscode/Invoke-MSTestWithCoverage.PackageRate.ps1, rather
+than adding it inline to Invoke-MSTestWithCoverage.Helpers.ps1 (plan tasks P1-T8 and P1-T9).
+The 500-line ceiling is a hard, non-negotiable repository constraint that takes precedence
+over spec.md's stated file-placement preference where the two conflict; spec.md's substantive
+requirement (one new pure per-package rate helper, reused by both the document-level
+summarizer and the merge function) is honored in full, and only its file placement is
+adjusted.
+
+## Second Constraint — Invoke-MSTestWithCoverage.Helpers.Tests.ps1
+
+tests/scripts/vscode/Invoke-MSTestWithCoverage.Helpers.Tests.ps1 is measured at 498 lines,
+leaving 2 lines of headroom. This file is not named in the plan's stated size rationale, but
+it is a binding constraint on Phase 1: P1-T5 and P1-T6 add new It cases to it, and P1-T4
+edits an existing test in it. The plan already routes the new `Get-CoberturaPackageLineSummary`
+Describe block (P1-T1, P1-T2) to the separate new file
+tests/scripts/vscode/Invoke-MSTestWithCoverage.PackageRate.Tests.ps1, which removes the
+largest planned addition from this file. P1-T14's size check is the gate that confirms the
+remaining additions still fit, and P1-T14's own acceptance text prescribes the remedy
+(extracting the most recently added self-contained Describe block into a further sibling file)
+if the resulting count exceeds 500.
+
+## Output Summary
+
+All seven files measured. Every one is currently at or under the 500-line ceiling. Two files
+carry material size pressure into Phase 1:
+scripts/vscode/Invoke-MSTestWithCoverage.Helpers.ps1 at 491 lines (9 lines of headroom,
+8 on the planning-pass count) and
+tests/scripts/vscode/Invoke-MSTestWithCoverage.Helpers.Tests.ps1 at 498 lines (2 lines of
+headroom). Both are handled by Phase 1's split of the new helper and its Describe block into
+sibling PackageRate files, with P1-T14 as the confirming gate.