GetChats now returns only root chats (parent_chat_id IS NULL).
A new GetChildChatsByParentIDs query fetches children for visible
roots and embeds them in each parent's Children field. The
singular getChat endpoint does the same.
Archive invariant is one-way: parent archived implies child
archived. Parent archive/unarchive cascades via root_chat_id.
Individual child archive is permitted; child unarchive while the
parent is archived is rejected atomically (row lock on child,
re-read parent inside the transaction). Embedded children are
filtered by the caller's archive state so individually-archived
children stay hidden from active-parent views.
Gitsync MarkStale uses GetChatsByWorkspaceIDs directly;
MarkStaleParams.OwnerID removed (dead after the switch).
Frontend: buildChatTree reads from the embedded children field,
WebSocket handlers route child events into the parent's children
array, and archiving a child strips it from the parent cache.
## Problem
Subagent chats were receiving git context (branch, remote origin, PR
status) from their parent or sibling chats' git operations. When a git
operation triggers external auth, the workspace agent sends `chat_id`
identifying which chat initiated it — but this was broken at two levels:
1. **Agent side:** `CODER_CHAT_ID` was never injected into process
environments. `chatd` sets `Coder-Chat-Id` HTTP headers and the
agent extracts them for process isolation, but never propagated
`CODER_CHAT_ID` to `cmd.Env`. So `gitaskpass` always sent an empty
`chat_id`.
2. **Server side:** `workspaceAgentsExternalAuth` ignored the `chat_id`
query param. `MarkStale` broadcast git context to **all** chats on
the workspace via `filterChatsByWorkspaceID`.
## Fix
- Inject `CODER_CHAT_ID` into `cmd.Env` in `agentproc` when the chat
ID is known, so `gitaskpass` can read and forward it.
- Read `chat_id` from query params in `workspaceAgentsExternalAuth`
and thread it through `chatGitRef`.
- Refactor `MarkStale` to accept a `MarkStaleParams` struct. When
`ChatID` is provided, target only that specific chat. When empty
(legacy agents, non-chat git operations), fall back to the existing
workspace-wide broadcast.
- Extract `markStaleSingle` helper to deduplicate the upsert+publish
logic.
<details><summary>Investigation notes</summary>
### Data flow before fix
```
chatd → sets Coder-Chat-Id header on agent conn
agent → extracts chatID, stores on process struct
agent → does NOT set CODER_CHAT_ID in cmd.Env ← gap 1
gitaskpass → reads CODER_CHAT_ID (always empty), sends chat_id=""
server handler → ignores chat_id query param ← gap 2
MarkStale → broadcasts to ALL workspace chats
```
### Data flow after fix
```
chatd → sets Coder-Chat-Id header on agent conn
agent → extracts chatID, stores on process struct
agent → sets CODER_CHAT_ID in cmd.Env
gitaskpass → reads CODER_CHAT_ID, sends chat_id=<uuid>
server handler → reads chat_id, passes to MarkStale
MarkStale → targets only that specific chat
```
</details>
## Summary
Adds read/unread tracking for chats so users can see which agent
conversations have new assistant messages they haven't viewed.
## Backend Changes
- Adds `last_read_message_id` column to the `chats` table (migration
000439).
- Computes `has_unread` as a virtual column in `GetChatsByOwnerID` using
an `EXISTS` subquery checking for assistant messages beyond the read
cursor.
- Exposes `has_unread` on the `codersdk.Chat` struct and auto-generated
TypeScript types.
- Updates `last_read_message_id` on stream connect/disconnect in
`streamChat`, avoiding per-message API calls during active streaming.
- Uses `context.WithoutCancel` for the deferred disconnect write so the
DB update succeeds even after the client disconnects.
## Frontend Changes
- Bold title (`font-semibold`) for unread chats in the sidebar.
- Small blue dot indicator next to the relative timestamp.
- Suppresses unread indicator for the currently active chat via
`isActive` from NavLink.
## Design Decisions
- Only `assistant` messages count as unread — the user's own messages
don't trigger the indicator.
- No foreign key on `last_read_message_id` since messages can be deleted
(via rollback/truncation) and the column is just a high-water mark.
- Zero API calls during streaming: exactly 2 DB writes per stream
session (connect + disconnect).
- Unread state refreshes on chat list load and window focus. The
`watchChats` WebSocket optimistically marks non-active chats as unread
on `status_change` events, but does not carry a server-computed
`has_unread` field. Navigating to a chat optimistically clears its
unread indicator in the cache.
## Problem
When chatd pushes a branch and then creates a PR (e.g. `git push`
followed by `gh pr create`), the gitsync background worker often picks
up the stale `chat_diff_statuses` row between the two operations. At
that point no PR exists yet, so the worker skips the row. However, the
acquisition SQL locks the row for **5 minutes** (crash-recovery
interval), creating a dead zone where the PR diff is invisible in the UI
until the user manually navigates to the chat.
### Root cause
1. `git push` triggers `GIT_ASKPASS` → coderd external-auth handler →
`MarkStale()` sets `stale_at = now - 1s`
2. Background worker acquires the row within ~10s, atomically bumps
`stale_at = NOW() + 5 min` (crash-recovery lock)
3. Worker calls `ResolveBranchPullRequest` → no PR exists yet → returns
`nil` → worker skips with `continue`
4. `gh pr create` completes moments later, but uses its own auth (not
`GIT_ASKPASS`), so no second `MarkStale` fires
5. Row is locked for 5 minutes before the worker can retry
Loading the chat works immediately because `GET /chats/{chat}` calls
`resolveChatDiffStatus` synchronously, which discovers the PR inline.
## Fix
When `ResolveBranchPullRequest` returns nil (no PR yet) **and** the row
was recently marked stale (within 2 minutes), apply a short 15-second
backoff via `BackoffChatDiffStatus` instead of letting the 5-minute
acquisition lock stand. Outside the retry window, the worker skips the
row as before — no indefinite fast-polling for branches that never
receive a PR.
To make the "recently marked stale" check work, `updated_at` is no
longer overwritten by the acquisition and backoff SQL queries. This
preserves it as a reliable "last externally changed" timestamp (set by
`MarkStale` or a successful refresh).
### Behavior summary
| Scenario | `updated_at` age | Backoff | Effective retry |
|---|---|---|---|
| Fresh push, no PR yet | < 2 min | 15s (`NoPRBackoff`) | ~15s |
| Old row, no PR | ≥ 2 min | None (skip) | ~5 min (acquisition lock) |
| Error (any age) | Any | 120s (`DiffStatusTTL`) | ~120s |
| Success (any age) | Any | 120s (`DiffStatusTTL`) | ~120s |
## Changes
- **`coderd/database/queries/chats.sql`** — Remove `updated_at = NOW()`
from `AcquireStaleChatDiffStatuses` and `BackoffChatDiffStatus`
- **`coderd/database/queries.sql.go`** — Regenerated
- **`coderd/x/gitsync/worker.go`** — Add `NoPRBackoff` (15s) and
`NoPRRetryWindow` (2 min) constants; apply short backoff only within the
retry window
- **`coderd/x/gitsync/worker_test.go`** — Add
`TestWorker_NoPR_RecentMarkStale_BacksOffShort` and
`TestWorker_NoPR_OldRow_Skips`
- Moves `coderd/chatd/`, `coderd/gitsync/`, `enterprise/coderd/chatd/`
under `x/` parent directories to signal instability
- Adds `Experimental:` glue code comments in `coderd/coderd.go`
> 🤖 This PR was created with the help of Coder Agents, and was
reviewed by my human. 🧑💻
Mathias Fredriksson