fix(cpp): resolve cross-namespace same-tail inheritance bases bridge-held (#1993)

[magyargergo]

Summary

Follow-up to #1981 / #1982. PR #1981 landed a targeted bridge (tagNamespacePrefixes + a resolveDefGraphId namespace-prefixed retry) that fixes the within-namespace same-tail heritage case (NS::A::Inner vs NS::B::Inner, distinguished by the class chain). The residual: a cross-namespace same-tail base (NS1::A::Inner vs NS2::A::Inner) — both key the namespace-omitted A.Inner in the qualifiedNames resolution index, so resolveQualifiedInheritanceBase could not pick a winner and the deriving classes cross-wired (DB's EXTENDS bound to NS1's A::Inner).

Fixed bridge-held — without flipping the class-chain-only qualifiedName invariant (which would re-bite two-phase lookup / UDC / brace-init) and without re-keying the resolution index.

Fix

The namespacePrefix sidecar (set by tagNamespacePrefixes, deliberately separate from qualifiedName) already records each namespaced def's enclosing namespace. Two sidecar-only changes:

1. tagNamespacePrefixes now also tags defs declared directly in a namespace (e.g. the deriving NS1::DA), composed identically to the existing class-nested path. The original loop only reached class-nested defs (A::Inner).
2. resolveQualifiedInheritanceBase, on a same-tail tie at a key, breaks the tie by preferring the candidate whose namespacePrefix matches the deriving class's — the base in the same enclosing namespace. It still refuses when the sidecar can't pick a unique.

def.qualifiedName and the qualifiedNames index keys are untouched, so two-phase lookup, UDC ranking, brace-init, and file-local linkage are unaffected. The deferred root-cause work (making qualifiedName namespace-inclusive and removing the bridge) is unchanged and out of scope.

Tests

New cpp-cross-namespace-same-tail fixture + test (registry-primary, in the cpp parity expected-failures like the #1982 namespaced tests): NS1.DA EXTENDS NS1.A.Inner and NS2.DB EXTENDS NS2.A.Inner — positive base-identity by the resolved node's qualifiedName, which fails pre-fix (DB cross-wired to NS1.A.Inner).

Verification

• cpp resolver suite: registry-primary 287/287, legacy green — no regression to brace-init, UDC, two-phase lookup, ADL, file-local linkage, or the within-namespace (Qualified nested-type node identity — resolution-side follow-up (Ruby same-tail routed-props/mixins + Rust inherent impls) #1982) namespaced-collision tests.
• tsc --noEmit clean; prettier clean.

Closes #1993.

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[magyargergo]

Superseded by same-repo stacked PR #2005.

[github-actions]

CI Report

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Pipeline Status

Stage	Status	Details
✅ Typecheck	success	tsc --noEmit
❌ Tests	failure	unit tests, 3 platforms
✅ E2E	success	gitnexus-web changes only

Test Results

Tests	Passed	Failed	Skipped	Duration
11057	11041	0	16	697s

✅ All 11041 tests passed

16 test(s) skipped — expand for details

• COBOL pipeline benchmark > scales with file count
• C++ ADL emit benchmark > emit phase scales sub-quadratically with co-scaled files and sites
• C++ pipeline benchmark > scales with file count
• C# pipeline benchmark > scales with file count — namespaces spread across the solution
• C# pipeline benchmark > scales with file count — all types in one (global) namespace bucket
• C# pipeline benchmark > scales with file count — all types in one (named) namespace bucket
• Go pipeline benchmark > scales with file count (workers enabled)
• Go pipeline benchmark — worker pool (issue Worker idle timeout kills long Go scope extraction and surfaces as Napi::Error during analyze #1848) > does not quarantine the large generated Go file on sub-batch idle timeout
• Go structural interface detection benchmark > scales linearly with interface × struct count
• Go structural interface detection split-phase benchmark > separates index-build and detection time
• PHP pipeline benchmark > scales with file count (workers enabled)
• Ruby pipeline benchmark > scales with file count (workers enabled)
• Rust pipeline benchmark > scales with file count (workers enabled)
• Vue pipeline benchmark > scales with component count
• run.cjs direct-exec entrypoint (fix(cli): steer docs, skills, and hooks through a CLI-neutral project-local runner (#1939) #1945) > resolves a .cmd shim via the Windows shell branch, passing args and exit code
• buildTypeEnv > known limitations (documented skip tests) > Ruby block parameter: users.each { |user| } — closure param inference, different feature

Code Coverage

Tests

Metric	Coverage	Covered	Base	Delta	Status
Statements	80.33%	38724/48204	79.84%	📈 +0.5	🟢 ████████████████░░░░
Branches	68.88%	24613/35731	68.5%	📈 +0.4	🟢 █████████████░░░░░░░
Functions	85.55%	4034/4715	84.94%	📈 +0.6	🟢 █████████████████░░░
Lines	83.94%	34835/41496	83.36%	📈 +0.6	🟢 ████████████████░░░░

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