docs: update planning artifacts for platform challenge handling

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

task_plan.md

@@ -4,7 +4,7 @@
 Continue the desktop AI monitoring implementation by first adding a client-side local scheduler with durable queueing and adaptive execution policy, then adding a reusable hidden Playwright CDP execution layer that attaches to Electron Chromium and reuses existing account partitions.
 
 ## Current Phase
-Phase 60
+Phase 68
 
 ## Phases
 ### Phase 1: Progress Verification
@@ -419,6 +419,42 @@ Phase 60
 - [x] Remove temporary visual artifacts and record results
 - **Status:** complete
 
+### Phase 63: Human-Verification Failure Reproduction
+- [x] Trace account-level challenge classification, same-model failover, task admission, and desktop notifications
+- [x] Add deterministic regression coverage for challenge failover, single-account cancellation, and system alerts
+- [x] Confirm the tests reproduce the current incorrect behavior
+- **Status:** complete
+
+### Phase 64: Account Failover, Cancellation, And Alerts
+- [x] Keep challenge blocking scoped to the failed account when another same-model account is usable
+- [x] Cancel all later tasks for the model when no alternate usable account remains
+- [x] Show a system notification for every client/platform error while preserving in-app diagnostics
+- **Status:** complete
+
+### Phase 65: Verification And Delivery
+- [x] Run focused desktop/server regression tests and type/build checks
+- [x] Confirm no challenge path can silently continue on the failed account
+- [x] Record final behavior, changed files, and residual live-verification limits
+- **Status:** complete
+
+### Phase 66: Local Queue Challenge Reproduction
+- [x] Trace monitor scheduler activation, local queue cancellation, and server task invalidation after a challenge
+- [x] Build a deterministic failing test with two queued same-platform tasks and one usable account
+- [x] Confirm the later task is currently represented as another failure instead of cancellation
+- **Status:** complete
+
+### Phase 67: Platform Circuit Breaker
+- [x] Immediately block the challenged platform when no alternate account remains
+- [x] Remove/cancel queued and deferred local tasks for that platform before adapter execution
+- [x] Keep other platforms running and preserve same-platform failover when another account is usable
+- **Status:** complete
+
+### Phase 68: Circuit-Breaker Verification
+- [x] Run focused scheduler/runtime tests, full desktop tests, typecheck, build, and server checks
+- [x] Verify the screenshot sequence cannot recur in the deterministic harness
+- [x] Record final behavior and any live-environment caveat
+- **Status:** complete
+
 ## Key Questions
 1. How should the desktop client defer and locally optimize monitor-task execution without violating one-task-per-platform serialism?
 2. What is the smallest durable local cache that allows same-day resume while safely dropping stale next-day monitor tasks?
@@ -481,6 +517,11 @@ Phase 60
 ## Errors Encountered
 | Error | Attempt | Resolution |
 |-------|---------|------------|
+| Runtime invalidation payload included unsupported `platform` field | 1 | Remove the redundant field; account ID and message already identify the health event |
+| Server regression still expected old literal skip reason and 10 SQL args | 1 | Update assertions to the new parameterized skip reason/cancellation payload and 11 args |
+| Authorization bulk-cancellation patch context did not match the existing SQL argument block | 1 | Split the server change into smaller exact-context patches |
+| zsh no-match on optional Vitest config glob | 1 | Use `rg --files` or explicit paths instead of a shell glob |
+| Planning-file patch context did not match the existing error table | 1 | Re-read the exact section and apply a narrower patch |
 | None yet | 1 | N/A |
 | `make sqlc-generate` failed because `sqlc.yaml` points to `../../migrations/`, which resolves to `server/internal/migrations` | 1 | Fix schema path to repository-relative `../../../migrations/` and then generate code |
 | `make lint` initially failed on several `errcheck` and one `ineffassign` warning | 1 | Fixed transaction defers, the middleware test Redis set call, and the dead increment in `article_service.go` |