Problem

DIFF-SYNC batches silently re-introduce imports from gutted modules (pi-embedded, model-catalog, memory, skills, etc.). These imports compile because stub files exist, but they exercise dead code paths. The existing gates (build, lint, rebrand) don't catch this.

Proposed Solution

A CI check script (similar to check-no-random-messaging-tmp.mjs and the rebrand gate) that:

1. Maintains a list of known-dead module patterns:

   agents/pi-embedded
   agents/model-catalog
   agents/model-fallback
   agents/model-selection
   agents/skills
   agents/sandbox
   agents/pi-embedded-runner
   memory/
   acp/control-plane
   acp/runtime
   

2. Greps all .ts files for from ".*{pattern}" or import.*{pattern}

3. Allows exceptions list (e.g., test files that mock for negative testing, the system-prompt.test.ts negative assertion)

4. Fails CI if any non-excepted import from a dead module is found

Implementation

• Script: scripts/check-no-zombie-imports.mjs (matches naming of existing check-no-random-messaging-tmp.mjs)
• CI integration: Add as a step in the CI workflow, alongside rebrand-gate
• Dead module list: maintain in the script (or a config file)
• Exception list: inline comments // zombie-gate-allow: {reason} or a separate config

Why CI, not just DIFF-SYNC

• DIFF-SYNC gates run only during sync batches
• Manual changes (feature work, bug fixes) can also accidentally import from dead modules
• CI catches ALL paths — sync, manual, cherry-pick, hotfix

Relationship to #2192

Issue #2192 (stub audit) eliminates the stub FILES. This gate prevents new IMPORTS. Together they close both vectors:

• Audit and eliminate DIFF-SYNC stub files (59 disposition misclassifications) #2192: Remove existing stubs (eliminate the import target)
• This issue: Prevent new imports (even if stubs somehow return)

Priority

Should be implemented alongside or after #2192. The gate is most valuable once stubs are eliminated — at that point, any import from a dead module is a guaranteed build break, but the gate provides earlier, clearer feedback than a type error.