feat(loop): persist loop settings on un-loop; symmetric re-loop restore (mitto-0do)

[inercia]

Summary

Extends the archive/unarchive loop-persistence feature (mitto-vmp) to the un-loop button, and makes loop ⇄ un-loop a symmetric, non-destructive toggle across every interface (REST and MCP).

Previously, pressing Unloop (DELETE /api/sessions/{id}/loop) hard-deleted loop.json, discarding the configuration. Now it detaches: loop.json is moved to loop.saved.json so the prompt / frequency / trigger / enabled state survive, and the conversation reverts to a regular one (loop_configured=false) exactly as before. Pressing Make loop restores the saved settings — preserving the enabled state they had at un-loop time (an active loop resumes; a paused draft comes back paused). Iteration/duration counters and the stopped reason are reset so the restored loop starts its budget fresh.

Closes mitto-0do.

Changes

Session layer — internal/session/loop.go

• New loop.saved.json slot + LoopStore.Detach / GetSaved / ClearSaved.

REST — internal/web/handlers

• handleDeleteLoop now detaches instead of deleting (same 204 + loop_updated(nil) broadcast).
• New POST /api/sessions/{id}/loop/restore (handleRestoreLoop): restores the saved config, resets counters, clears the saved slot, re-broadcasts, bootstraps onCompletion; 404 when nothing is saved.
• handleSetLoop clears the saved slot after Set so a freshly-defined loop supersedes stale saved settings.

MCP — internal/mcpserver/server.go

• On create-loop (isNew) via mitto_conversation_update, clear the saved slot after Set — parity with the REST make-loop path.

Frontend — web/static

• handleMakeLoop tries POST /loop/restore first, falling back to a blank draft PUT on 404; un-loop toast notes settings are saved for later restore.
• Added endpoints.sessions.loopRestore.

Design notes

• Symmetric enabled state: re-loop restores the exact enabled state (active vs. paused) the loop had when detached — like archive ⇄ unarchive.
• loop_enabled:false via MCP stays "pause" (keeps loop.json via MarkStopped); it is intentionally not a full un-loop. The consistency fix therefore lives on the create-loop side (clear stale saved slot), not on disable.
• Clear is explicit, not inside Set(): the restore handler calls Set(saved) then ClearSaved(); keeping the lifecycle explicit matches the existing Detach/GetSaved/ClearSaved style.

Testing

• Session: Detach/GetSaved/ClearSaved round-trips, not-found paths, overwrite-latest.
• REST: full un-loop → restore round-trip (prompt + enabled state preserved, counters reset, saved slot cleared), restore-404, set-clears-saved-slot.
• MCP: create-loop clears the saved slot.

Gate results

gofmt clean · go build ./... ok · go vet clean · go test ./internal/session ./internal/web/handlers ./internal/mcpserver pass · node --check on app.js + endpoints.js ok.

[Copilot]

Pull request overview

This PR makes loop ⇄ un-loop a symmetric, non-destructive toggle across REST/MCP/UI by preserving loop settings on un-loop (detach to loop.saved.json) and restoring them on re-loop (new restore endpoint + UI behavior).

Changes:

• Session storage: add a saved loop slot (loop.saved.json) with Detach, GetSaved, and ClearSaved.
• REST + UI: DELETE /loop now detaches (preserves settings) and the UI attempts POST /loop/restore before creating a blank draft loop.
• REST + MCP parity: clearing the saved slot after a fresh loop Set to prevent stale restores; add tests covering detach/restore flows.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
web/static/utils/endpoints.js	Adds a frontend endpoint helper for POST /api/sessions/{id}/loop/restore.
web/static/app.js	UI “Make loop” first attempts restore; un-loop toast now communicates settings are preserved.
internal/web/handlers/session_loop.go	Routes the new restore sub-path to a dedicated handler.
internal/web/handlers/session_loop_write.go	Clears any saved slot after a fresh PUT loop set to avoid stale restore.
internal/web/handlers/session_loop_test.go	Adds REST tests for un-loop → restore round-trip, restore-404, and set-clears-saved.
internal/web/handlers/session_loop_run.go	Implements detach-on-delete and the new restore endpoint.
internal/session/loop.go	Adds loop.saved.json support and LoopStore APIs for detach/saved management.
internal/session/loop_test.go	Adds unit tests for Detach, GetSaved, ClearSaved, and overwrite semantics.
internal/mcpserver/server.go	Clears the saved slot after MCP create-loop (isNew) for parity with REST.
internal/mcpserver/server_test.go	Adds MCP test verifying create-loop clears any previously-detached saved slot.

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