fix(retirement): close projection and launch contract gaps

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a02b7c-1c49-76a0-955a-49e7b3ddfc0d

api/routers/identifier_migrations.py

@@ -0,0 +1,44 @@
+from dataclasses import asdict
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from api.database import get_session
+from api.schemas.identifier_migration import (
+    SealedProjectionRepairReceiptRead,
+    SealedProjectionRepairSubmit,
+)
+from api.services.work_record_identifier_migration import (
+    IdentifierMigrationError,
+    repair_absent_prederivation_projection,
+)
+
+router = APIRouter(prefix="/identifier-migrations", tags=["identifier-migrations"])
+
+
+@router.post(
+    "/sealed-projection-repairs",
+    response_model=SealedProjectionRepairReceiptRead,
+)
+async def repair_sealed_projection(
+    body: SealedProjectionRepairSubmit,
+    session: AsyncSession = Depends(get_session),
+) -> dict:
+    """Restore one exact pre-derivation workplan unit into an absent projection."""
+    try:
+        receipt = await repair_absent_prederivation_projection(
+            session,
+            body.plan,
+            body.repo_slug,
+            body.unit,
+            expected_plan_sha256=body.expected_plan_sha256,
+            source_revision=body.source_revision,
+            source_fingerprint=body.source_fingerprint,
+            source_clean=body.source_clean,
+            source_synchronized=body.source_synchronized,
+            primary_confirmed=body.primary_confirmed,
+            projection_identity=body.projection_identity,
+        )
+    except IdentifierMigrationError as exc:
+        raise HTTPException(status_code=409, detail=str(exc)) from exc
+    return asdict(receipt)