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Ethan
c4ef94aacf
## Problem Chats with a persisted `agent_id` binding hang indefinitely when the workspace is stopped. The stale agent row still exists in the DB, so `ensureWorkspaceAgent` succeeds, but the dial blocks forever in `AwaitReachable`. The MCP discovery goroutine used an unbounded context, so `g2.Wait()` never returned and the LLM never started. ## Fix Three targeted changes restore the pre-binding behavior where stopped workspaces degrade gracefully instead of blocking: 1. **`dialWithLazyValidation`**: "no agents in latest build" is now a terminal fast-fail — the hanging dial is canceled and `errChatHasNoWorkspaceAgent` returned immediately, instead of falling through to `waitForOriginalDial`. 2. **Pre-LLM workspace setup**: MCP discovery and instruction persistence gate on `workspaceAgentIDForConn` before attempting any dial. MCP discovery is bounded by a 5s timeout and checks the in-memory tool cache first (using the cheap cached agent from `ensureWorkspaceAgent`), so the common subsequent-turn path has zero DB queries. 3. **`persistInstructionFiles`**: tracks whether the workspace connection succeeded and skips sentinel persistence on failure, so the next turn retries if the workspace is restarted. ## Scenarios **Running workspace, subsequent turn (hot path):** MCP cache hit via in-memory cached agent. Zero DB queries, zero dials. Unchanged from #23274. **Stopped workspace, persisted binding (the bug):** MCP cache hit (stale descriptors, fine — they fail at invocation). Pre-LLM setup completes instantly. Tool invocation enters `dialWithLazyValidation`, dial fails or hangs, validation discovers no agents, returns `errChatHasNoWorkspaceAgent`. Model sees the error and can call `start_workspace`. **New chat, running workspace:** `ensureWorkspaceAgent` resolves via latest-build, persists binding. MCP discovery dials and caches tools. **New chat, stopped workspace:** `ensureWorkspaceAgent` finds no agents, returns `errChatHasNoWorkspaceAgent`. Pre-LLM setup skips. LLM starts with built-in tools only. **Rebuilt workspace (agent switched):** MCP cache hit with stale agent (harmless for one turn). Tool invocation dials stale agent, fails fast, `dialWithLazyValidation` switches to new agent, persists updated binding. **Workspace restarted after stop:** No sentinel was persisted during the stopped turn, so instruction persistence retries. Agent binding switches to the new agent via `workspaceAgentIDForConn`. **Transient DB error during validation:** Not `errChatHasNoWorkspaceAgent`, so `dialWithLazyValidation` falls through to `waitForOriginalDial` (cannot prove stale). No false positive. **Tool invocation on stopped workspace:** `getWorkspaceConn` calls `ensureWorkspaceAgent` (returns stale row), then `dialWithLazyValidation` validation discovers no agents, returns `errChatHasNoWorkspaceAgent`, cached state cleared, error returned to model.