fix: reset message stream when conversation clears

[adliebe]

Summary

• closes Message stream stays connected after clearing conversation #267
• derives visible connection, error, and typing state from the active conversation id so stale state from a cleared or changed conversation does not leak into the UI
• clears the stored EventSource ref during cleanup and ignores late typing-poll completions after effect cleanup
• adds a regression test for clearing conversationId after an SSE connection has opened

Validation

• PNPM_CONFIG_IGNORE_SCRIPTS=true pnpm exec vitest run src/hooks/useMessageStream.test.ts -> 11 passed
• PNPM_CONFIG_IGNORE_SCRIPTS=true pnpm exec eslint src/hooks/useMessageStream.ts src/hooks/useMessageStream.test.ts -> 0 errors, 0 warnings
• PNPM_CONFIG_IGNORE_SCRIPTS=true pnpm exec tsc --noEmit -> passed
• git diff --check -> passed

[adliebe]

Submitted for the active Ugig testing/fix gig: https://ugig.net/gigs/abd6b2a0-e728-48cf-a46f-f99e419ed94e

Scope: real message-stream state bug, issue #267, focused fix plus regression test and validation listed in the PR body.

[greptile-apps]

Greptile Summary

This PR fixes stale UI state when a conversation is cleared or switched by replacing per-state boolean/string tracking with an integer stream-ID scheme. Each effect run gets a unique streamId; derived values (isConnected, error, isOtherTyping) only surface if their stored stream ID matches the current one, so cleared or switched conversations can never expose state from a prior session.

• Replaces isConnected/error state with connectedStreamId and connectionError (keyed by streamId + conversationId), and wraps isOtherTyping in an equivalent keyed object; all three derived values are now computed synchronously from streamIdRef.current on every render.
• Adds a cancelled flag and streamIdRef guard to the typing-poll effect so in-flight fetches after cleanup are silently dropped rather than updating state.
• Adds three regression tests covering: clearing the conversation ID resets connection state, reconnecting to the same ID waits for onopen, and no stale errors appear before reconnect opens.

Confidence Score: 5/5

Safe to merge — the stream-ID scheme correctly isolates all connection, error, and typing state per effect run, and the three new regression tests directly exercise the cleared-conversation and same-ID-reconnect paths.

The staleness fix is logically sound: every handler (onopen, onmessage, onerror) guards against stale streams by comparing the captured streamId to streamIdRef.current, and the polling effect captures both a cancelled flag and the stream ID to discard in-flight fetches after cleanup. All three derived values resolve correctly across the null to conv-123 and conv-123 to null to conv-123 transitions that were the original bug, and the new tests verify each scenario end-to-end.

No files require special attention.

Important Files Changed

Filename	Overview
src/hooks/useMessageStream.ts	Core hook refactored to use a monotonically-increasing stream ID for staleness detection; derived state logic is correct and all handler guards (onopen, onmessage, onerror) properly check the captured streamId against streamIdRef.current.
src/hooks/useMessageStream.test.ts	Three new regression tests added; all cover the null-clear and same-ID-reconnect paths that were the original bug, with appropriate use of act, waitFor, and synchronous assertions where effects have already been flushed by rerender.

Sequence Diagram

sequenceDiagram
    participant C as Component
    participant H as useMessageStream
    participant ES as EventSource
    participant API as /typing API

    C->>H: "conversationId=conv-123"
    H->>H: "streamIdRef++ streamId=1"
    H->>ES: new EventSource
    ES-->>H: onopen
    H->>H: "setConnectedStreamId(1), isConnected=true"
    H->>API: "start polling streamId=1"

    C->>H: "conversationId=null"
    H->>ES: close
    H->>H: "streamIdRef 1->2->3, setConnectedStreamId(null)"
    H->>H: "isConnected=false, cancel poll"

    C->>H: "conversationId=conv-123"
    H->>H: "streamIdRef 3->4, isConnected=false"
    H->>ES: new EventSource
    ES-->>H: "onopen streamIdRef===4"
    H->>H: "setConnectedStreamId(4), isConnected=true"
    H->>API: "start polling streamId=4"

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_{Reviews (2): Last reviewed commit: "fix: reset stale stream state before rec..." | Re-trigger Greptile}

[adliebe]

Pushed a follow-up fix for the Greptile P1: reset stale connection/error/typing state whenever a new stream attempt starts, and key late SSE/poll updates by stream id so a null -> same conversation reconnect cannot report connected or show stale errors before onopen.\n\nValidation:\n- pnpm vitest run src/hooks/useMessageStream.test.ts -> 13 passed\n- pnpm type-check -> passed