docs(501): post-base-merge toolchain and base-reconciliation evidence

[drmoisan]

docs(501): post-base-merge toolchain and base-reconciliation evidence

Docs-only follow-up to PR #659 (epic child breadcrumb-coordinator-hub-defects-501). It adds the
five QA-gate evidence artifacts that attest the tree actually merged into
epic/quickfiler-bug-family-integration passes the full C# toolchain. No production or test source
file is touched.

Why this follow-up exists

PR #659 was reviewed and gated against head d86ee40d, whose CI run 33128535269 concluded
success. Sibling 476 then merged as PR #658 (5793b8c7), leaving d86ee40d eleven commits behind
the integration tip, so run 33128535269 no longer gated the tree that would result from merging.

This branch was therefore re-merged onto 5793b8c7 (merge commit 9c6c0b4a) and the full toolchain
was re-run against the reconciled tree. While that pass was in flight, PR #659 was merged as
4cb709db. That merge commit's tree is 0bdc974e... — byte-for-byte identical to the tree of the
local reconciliation merge 9c6c0b4a — so the toolchain results recorded here describe exactly the
tree now on the integration branch. Only the evidence itself remained unlanded, and this PR lands it.

Contents

Five artifacts under docs/features/active/breadcrumb-coordinator-hub-defects-501/evidence/qa-gates/,
all timestamped 2026-08-28T00-14:

Artifact	Gate	Result
post-basemerge-base-reconciliation	base merge + divergence + ownership	0 behind; 12 sibling csproj entries intact
post-basemerge-csharpier	Step 1 formatting	Checked 1547 files, 0 rewrites, EXIT 0
post-basemerge-msbuild-analyzers	Step 2 analyzers	0 errors, EXIT 0
post-basemerge-msbuild-nullable	Step 3 nullable	0 errors, EXIT 0
post-basemerge-test-coverage	Step 4 MSTest + coverage	6745/6745 passed, EXIT 0

Toolchain results recorded

Run in the mandated order with no step rewriting a file, so the loop did not restart:

1. dotnet tool run csharpier format . / check . — Checked 1547 files in 4975ms, EXIT 0.
2. msbuild TaskMaster.sln /t:Rebuild /m /p:Configuration=Debug "/p:Platform=Any CPU" /p:EnableNETAnalyzers=true /p:EnforceCodeStyleInBuild=true — 0 Error(s), EXIT 0.
3. msbuild TaskMaster.sln /t:Rebuild /m /p:Configuration=Debug "/p:Platform=Any CPU" /p:TreatWarningsAsErrors=true — 0 Error(s), EXIT 0.
4. pwsh -NoProfile -File ./scripts/vscode/Invoke-MSTestWithCoverage.ps1 -SearchRoot . -Configuration Debug -CoverageOutput coverage/postchange.cobertura.xml — Total tests: 6745, Passed: 6745, EXIT 0.

Coverage on the reconciled tree: line-rate 85.1494% (54545 / 64058), branch-rate 79.1998%
(12965 / 16370). Both clear the uniform >= 85% line and >= 75% branch floors.

Analyzer and nullable gates are non-vacuous

Both MSBuild steps used /t:Rebuild, never /t:Build. Counted against the build logs, the
Skipping target "CoreCompile" count is 0 for both, against 51 and 65 real CoreCompile
target executions respectively. A warm /t:Build would have skipped every project and run no
analyzer at all, so this records a gate that could actually have failed.

One recorded environmental test re-run

The first coverage attempt exited -1 after 1694 passing tests with zero failing tests and no run
summary — the signature of an aborted host rather than a failing assertion, with two sibling children
building concurrently in adjacent worktrees. One re-run was taken on the byte-identical tree and is
the run recorded above. No source file changed between the two attempts.

Base reconciliation

git rev-list --left-right --count origin/epic/quickfiler-bug-family-integration...HEAD reported
0 6 after the reconciliation merge: zero base-only commits, so the integration tip is contained in
full.

The pure-deletion scan reported one row, 0 50 QuickFiler/Viewers/BreadcrumbBridgeCoordinator.cs.
The invariant that matters is that no file loses content the base gained, and it holds here on two
independent grounds:

1. no base commit in the range 4f238289..5793b8c7 touched that file, so it held no base-gained
   content to lose;
2. the 50 removed lines are SetSuggestions, SuggestionsUpgrade, PopulateSuggestionsAsync and
   AddItems, all four of which are present in the new partial
   QuickFiler/Viewers/BreadcrumbBridgeCoordinator.Suggestions.cs. The type is partial, so the
   public surface is unchanged; the split exists to hold the file under the 500-line limit.

Merged siblings' project-file entries preserved

QuickFiler.Test/QuickFiler.Test.csproj retains all twelve entries contributed by merged siblings —
493's two Controllers\QfcItemController.UiThreadDispatcherFixture* entries, 444's eight
Controllers\QfcCollectionController* entries, and 476's two Viewers\WebView2* entries — unmoved
and unreplaced. This feature's own single added entry stays inside the Viewers\Breadcrumb* region.

CI gate

Workflow-dispatch run 33129199041 on head 51cfa948 concluded success with all five required
checks green: format-check, build-analyzers, build-nullable, mstest-coverage, actionlint.
.github/workflows/ci.yml fires pull_request only on main and development, so a PR into the
epic integration branch receives no automatic checks and the gate is dispatched explicitly. No
workflow file is modified by this PR.

Issue linkage

This PR targets epic/quickfiler-bug-family-integration, not the default branch, so GitHub registers
no closing references from it. Issues #501, #462, #500 and #502 are addressed by the code already
merged in PR #659 and are closed at epic fan-in, not here. Issue #657 tracks the three non-blocking
review residuals dispositioned during the #659 review and stays open.

Risk

Documentation only: 5 added files, 213 insertions, 0 deletions, no file outside the feature's own
evidence/qa-gates/ directory.