[lifecycle-RSK] RSK-14: Route the provider through actor messages #1807

Tracking

• Epic: [lifecycle-RSK] Run-state kernel #1790
• Size: 1 SP (split if it grows)
• Blocked by: [lifecycle-RSK] RSK-13: Wrap run state in a task actor with a serialized mailbox #1806
• Design doc: docs/architecture/task-lifecycle-target-architecture.md (not yet on main)
• Ticket plan: docs/architecture/task-lifecycle-run-state-kernel-tickets.md (not yet on main)

Context

After #1806, ClineProvider and checkpointRestoreHandler still write run state through Task methods and the two direct writes at ClineProvider.ts:3572, 3588. This issue makes them send mailbox messages directly.

Developer Notes

• Replace the direct run-state writes and calls in src/core/webview/ClineProvider.ts and checkpointRestoreHandler.ts with mailbox messages.
• ClineProvider.ts is large. If the change exceeds 1 SP, split per call site and keep this issue as the tracker.
• Send the run-state view to the webview as its own small webview message when the run state changes. Do not add it to the full state post. Keep the partial-post optimizations (ClineProvider.ts:2438-2452, 2476-2491).
• Define the new webview message type in packages/types with the other ExtensionMessage types.
• Handle it in the webview state context (webview-ui/src/context/ExtensionStateContext.tsx), beside the messageUpdated case.
• Post the current run-state view once when the webview loads and when the focused task changes. Without that first post, a reloaded webview shows an empty view until the next transition.
• Cross-link feat(webview): incremental clineMessages delivery for focused task #630. This webview message follows the delta pattern that feat(webview): incremental clineMessages delivery for focused task #630 proposes for clineMessages. Do not implement feat(webview): incremental clineMessages delivery for focused task #630 here.
• Cover the change with provider and subtask E2E tests.

Exit criteria: the provider drives run state only through the mailbox. Tests and E2E pass.

Reversibility: behavior-preserving.