fix(chat): abort streaming fetch on unmount / stopGenerating

[zachdive]

Summary

• Wire an AbortController into useCreativeChatMutation and useParametricChatMutation so the streaming fetch + reader are cancelled when the view unmounts or stopGenerating fires.
• Fixes the "stuck loading forever" bug where a mid-stream unmount (error boundary from the react-resizable-panels crash, route change, tab close before pagehide) left the mutation orphaned — useIsMutating(['parametric-chat', conversationId]) stayed truthy and isLoading never cleared.

What changed

• Module-level Map<conversationId, AbortController> registry + exported abortActiveStream(id) so the View can abort externally.
• signal: controller.signal threaded through both fetch calls; catch block tags abort as AbortError and onError short-circuits — no Sentry noise, no "An error occurred" placeholder message written to the thread.
• useEffect unmount cleanup in each hook invokes abortActiveStream(conversationId) — this is the path that actually fixes the orphan case.
• stopGenerating in ParametricEditorView and CreativeEditorView now aborts client-side before the existing cancelRequest realtime signal (client drops connection → server-side signal tells the edge function to wind down).
• Streaming reader itself is untouched — scope is cancellation plumbing only.

Test plan

⚠️ Author could not test locally — browser verification still owed before merge.

• Start a long parametric generation, navigate away mid-stream; confirm Network tab shows the request cancelled and useIsMutating returns 0.
• Trigger an error during stream (throw in the reader loop); confirm no unhandled rejection, mutation settles cleanly.
• Verify the stopGenerating button still works end-to-end for both parametric and creative chat.
• Verify a stream that completes normally (no abort) still runs onSuccess and updates the conversation leaf as before.

🤖 Generated with Claude Code

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Summary by cubic

Abort streaming chat requests on unmount and when Stop Generating is pressed to prevent orphaned mutations and stuck loading states. Adds a per-conversation AbortController and ensures aborts are silent and never commit partial messages.

• Bug Fixes
  • Cancel streaming via AbortController on unmount and stopGenerating; views call abortActiveStream(conversationId) before cancelRequest.
  • Threaded signal into fetch; aborts throw AbortError and are ignored by onError (no Sentry, no user error).
  • Removed shadowed conversationId param from mutation fns to avoid abort registry misses; callers no longer pass it.
  • Fixed orphaned mutations where useIsMutating(['parametric-chat', conversationId]) stayed truthy after mid-stream unmount.
  • Hardened abort detection: isAbortError uses instanceof Error; dropped signal.aborted fallback.

^{Written for commit 375b5db. Summary will update on new commits.}

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Project	Deployment	Actions	Updated (UTC)
cadam	Ready	Preview, Comment	Apr 22, 2026 7:55pm

[supabase]

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[greptile-apps]

Greptile Summary

Adds AbortController plumbing to both chat mutations so that unmounting or pressing Stop Generating cancels the in-flight fetch and stream reader, fixing the orphaned-mutation/stuck-loading bug. The architecture (module-level registry, useEffect cleanup, onError guard) is sound, but there is one defect that defeats the entire abort handling path.

• P1 — isAbortError is broken for browser fetch aborts: fetch() and reader.read() abort by throwing a DOMException (name === 'AbortError'), not a regular Error. DOMException does not extend Error in browsers, so error instanceof Error is false, isAbortError() returns false, and every abort falls through to Sentry + error-message insertion — the exact behaviours the PR intended to suppress.

Confidence Score: 4/5

Not safe to merge until isAbortError is fixed; the abort guard is silently broken in the browser.

One P1 defect: isAbortError only checks instanceof Error, which will be false for every DOMException thrown by the Fetch API on abort, causing Sentry noise and error placeholder insertion on every cancelled stream. The rest of the plumbing (registry, useEffect cleanup, signal threading, view-level calls) is correct.

src/services/messageService.ts — the isAbortError function at line 29.

Important Files Changed

Filename	Overview
src/services/messageService.ts	Core abort plumbing added: AbortController registry, signal threading, isAbortError guard — but isAbortError uses instanceof Error which misses DOMException, breaking abort detection for browser fetch/reader aborts entirely.
src/views/CreativeEditorView.tsx	Minimal, correct change: imports abortActiveStream, calls it before cancelRequest in stopGenerating, adds conversation.id to useCallback deps.
src/views/ParametricEditorView.tsx	Mirror of CreativeEditorView change — abortActiveStream wired into stopGenerating correctly, deps updated.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["stopGenerating() / unmount"] --> B["abortActiveStream(conversationId)"]
    B --> C["controller.abort()"]
    B --> D["delete from activeStreamControllers"]
    C --> E["fetch / reader.read() throws DOMException"]
    E --> F{"isAbortError(error)?\nerror instanceof Error && name==='AbortError'"}
    F -->|"DOMException → instanceof Error = false\n❌ BROKEN PATH"| G["re-throw as real error"]
    G --> H["onError fires WITHOUT guard"]
    H --> I["Sentry.captureException 🔔"]
    H --> J["insertMessageAsync 'An error occurred' 💬"]
    F -->|"After fix: instanceof DOMException check"| K["wrap & re-throw AbortError"]
    K --> L["onError → isAbortError → early return ✅"]
    L --> M["No Sentry, no error message ✅"]

Loading

_{Reviews (3): Last reviewed commit: "fix(chat): address greptile v2 — shadowi..." | Re-trigger Greptile}

[cubic-dev-ai]

No issues found across 3 files

[greptile-apps]

isAbortError will not match the DOMException thrown by browser fetch/reader abort

In browsers, fetch() (and reader.read()) abort by throwing a DOMException with name === 'AbortError' — not a regular Error. DOMException does not extend Error on the browser's prototype chain, so error instanceof Error evaluates to false for every real abort thrown by the Fetch API. isAbortError() then returns false, the catch block re-throws the DOMException as a live error, onError skips its guard, Sentry fires, and the "An error occurred" placeholder is inserted — the exact behaviours this PR was meant to suppress.

Suggested change

	function isAbortError(error: unknown): boolean {
	return error instanceof Error && error.name === 'AbortError';
	}
	function isAbortError(error: unknown): boolean {
	return (error instanceof DOMException || error instanceof Error) && error.name === 'AbortError';
	}