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Nathan Sobo 55e47138e9 agent_ui: Unify draft and background threads into retained threads (#53737)
> **Foundation PRs:** #53732, #53733, #53734 — These three draft PRs
contain the base refactors (retained workspaces, agent panel overlay
split, ThreadId introduction) that this PR builds on.

## Goal

Remove `DraftId` and merge `draft_threads` + `background_threads` into a
single `retained_threads: HashMap<ThreadId, Entity<ConversationView>>`
in `AgentPanel`. A draft is just a thread that hasn't sent its first
message — no separate identity or storage needed.

## Changes

### agent_panel.rs
- Remove `DraftId` / `DraftIdCounter` / the `Global` impl
- Merge the two maps into `retained_threads`
- Add `thread_id: ThreadId` field to `BaseView::AgentThread`
- Rename methods: `create_draft` → `create_thread`, `activate_draft` →
`activate_retained_thread`, `remove_draft` → `remove_thread`, etc.
- Replace `clear_active_thread` with `show_or_create_empty_draft`
- Update `update_thread_work_dirs` to sync `ThreadMetadataStore` paths
when worktrees change
- Keep `load_agent_thread(...)` cleanup so activating a real thread
removes empty retained drafts

### sidebar.rs
- Remove `active_entry` derivation from `rebuild_contents` (was racing
with deferred effects)
- Add `sync_active_entry_from_panel` called from event handlers instead
- Simplify `ActiveEntry` — remove `ThreadActivation` struct, make
`session_id` optional
- Move `seen_thread_ids` to global scope (was per-group, causing
duplicate thread entries)
- Remove dead code: `clear_draft`, `render_draft_thread`
- Generalize `pending_remote_thread_activation` into
`pending_thread_activation` so all persisted-thread activations suppress
fallback draft reconciliation
- Set the activation guard before local persisted-thread activation
switches workspaces
- Make `reconcile_groups(...)` bail while a persisted-thread activation
is in flight
- On `ActiveViewChanged`, clear empty group drafts as soon as a pending
persisted-thread activation resolves

### thread_metadata_store.rs
- Make `ThreadMetadata.title` an `Option<SharedString>` with
`display_title()` fallback
- Add `update_worktree_paths` for batched path updates when project
worktrees change

### Other crates
- Update all `ThreadMetadata` construction sites and title display sites
across `agent_ui` and `sidebar`

## Fallback draft invariant

This PR now tightens the retained-thread invariant around fallback
drafts vs real thread activation/restoration:

- Fallback drafts are always empty
- User-created drafts worth preserving are non-empty
- While a persisted thread is being activated/restored/loaded, sidebar
reconciliation must not create an empty fallback draft for that target
group/workspace
- Once the real thread becomes active, empty fallback drafts in that
target group are removed

This is enforced by the sidebar-side activation guard plus existing
`AgentPanel` empty-draft cleanup after real-thread load.

## Tests

Added and/or kept focused sidebar regression coverage for:

-
`test_confirm_on_historical_thread_in_new_project_group_opens_real_thread`
-
`test_unarchive_into_inactive_existing_workspace_does_not_leave_active_draft`
-
`test_unarchive_after_removing_parent_project_group_restores_real_thread`
- `test_pending_thread_activation_suppresses_reconcile_draft_creation`

Focused test runs:

- `cargo test -p sidebar activate_archived_thread -- --nocapture`
- `cargo test -p sidebar unarchive -- --nocapture`
- `cargo test -p sidebar archive_last_thread_on_linked_worktree --
--nocapture`
- `cargo test -p sidebar
test_confirm_on_historical_thread_in_new_project_group_opens_real_thread
-- --nocapture`
- `cargo test -p sidebar
test_unarchive_into_inactive_existing_workspace_does_not_leave_active_draft
-- --nocapture`
- `cargo test -p sidebar
test_unarchive_after_removing_parent_project_group_restores_real_thread
-- --nocapture`
- `cargo test -p sidebar
test_pending_thread_activation_suppresses_reconcile_draft_creation --
--nocapture`

## Test fix

Fixed flaky `test_backfill_sets_kvp_flag` — added per-App `AppDatabase`
isolation in `setup_backfill_test` so backfill tests no longer share a
static in-memory DB.

Release Notes:

- N/A

---------

Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>
Co-authored-by: Mikayla Maki <mikayla@zed.dev>
2026-04-13 09:07:09 +00:00
..