docs(openspec): backfill missing proposals

openspec/changes/improve-cross-platform-stability/proposal.md

@@ -0,0 +1,35 @@
+# Change: Cross-Platform Stability and Robustness Improvements (P0+P1+P2)
+
+## Why
+
+- Account injection and detection across platforms are vulnerable to DB locks, version-detection failures, and OS-level differences.
+- Stability, diagnosability, and maintainability must improve without changing business semantics.
+
+## What Changes
+
+- Make the write flow atomic (transaction-wrapped).
+- Add DB lock retry and `busy_timeout`.
+- Add cache and lower-noise logging for version detection.
+- Add a more robust Windows fallback for version detection (read from `package.json`).
+- Introduce strategy-based injection routing (new/legacy/dual-write).
+- Add capability probing: prefer new format when new-format keys are detected.
+
+## Impact
+
+- Affected specs: `ide-auth-compat`
+- Affected code:
+  - `src/ipc/database/cloudHandler.ts`
+  - `src/ipc/database/handler.ts`
+  - `src/utils/antigravityVersion.ts`
+  - `src/utils/paths.ts` (this stage covers default runtime configuration path only)
+  - `src/types/db.ts`
+
+## Constraints
+
+- Do not change existing business semantics; only improve stability and structure.
+- This stage only covers the default runtime configuration path.
+
+## Risks
+
+- Transaction and retry logic may change when errors surface.
+- Capability probing may conflict with version detection unless priority is clearly defined.