codeql: preserve base/head configuration identity for PR differential analysis

[seonghobae]

Fresh consumer evidence

Wardnet PR ContextualWisdomLab/wardnet#129 current exact head 2cedf7098723cd12f59125e72f4354226165a112 completed its central current-head CodeQL dispatch successfully (Dispatch current-head CodeQL scan, job 103602823188, completed 2026-09-12T18:46:14Z). The same exact head still has GitHub Advanced Security CodeQL comparison check 103602491771 terminal neutral with title 1 configuration not found and this warning:

Code scanning cannot determine the alerts introduced by this pull request, because 1 configuration present on refs/heads/main was not found.

Missing configuration reported by GHAS: Default setup /language:rust.

Protected Wardnet base is main@f8260f1e03836039ff9463dd99fa982e4e270c4b. This means the current PR security path can execute/dispatch CodeQL while GHAS still cannot establish one compatible base/head CodeQL configuration identity for introduced-alert analysis. Treat that as incomplete security evidence, not a clean CodeQL comparison and not as consumer source debt.

Ownership boundary

The organization-central CodeQL producer/handler/settlement layer owns cross-repository CodeQL execution/evidence identity. Do not copy CodeQL workflows into Wardnet, disable Default Setup as a leaf workaround, weaken branch protection, synthesize statuses, or reinterpret a neutral comparison as GREEN.

This should be coordinated with #1929 and the active #2040/#2106 settlement stack. If those changes already supply the canonical fix, use this issue as the explicit GHAS configuration-identity acceptance gap rather than introducing a second producer/handler authority.

RED → GREEN acceptance

• For a PR exact head whose protected base has a Rust CodeQL configuration, the current-head analysis is published under a configuration identity that GHAS can pair with the protected-base configuration for introduced-alert computation.
• Exact unchanged-head canary has no 1 configuration not found / Default setup /language:rust warning and no neutral result caused by configuration discontinuity.
• Preserve immutable target repository, base SHA, head SHA, language, workflow/run identity, SARIF attribution, and terminal-receipt binding from the canonical CodeQL stack.
• Preserve current severity/gate semantics, immutable workflow/action pins, least privilege, and fail-closed behavior. No leaf-side custom workflow copy and no status fabrication.
• Add an executable contract/fixture covering the configuration identity expected by GHAS, including a negative case where base and head use incompatible/missing configuration identities.
• After protected central integration, verify on unchanged Wardnet 🧪 테스트 개선: parse_conflict_reason 함수 단위 테스트 추가 #129 exact head (or an equivalent Rust consumer canary) that GHAS can calculate introduced alerts and that the canonical central CodeQL terminal proof is still exact-head bound.

Search found no existing .github issue matching the exact Code scanning cannot determine the alerts introduced warning. Keep this issue distinct from scan execution success: dispatch completion alone does not satisfy differential-analysis evidence.