fix: reset dialog state and abort in-flight test on cancel (#2048)

[hunterxtang]

Fixes #2048 on main.

Root cause

Connector settings dialogs (Azure Blob, S3, IBM COS) are rendered
unconditionally in connector-cards.tsx with a stable key, so the
component never unmounts when the user closes the dialog. All
useState and useForm state — the connection-string field value,
the formError "Test the connection first…" message, and the
isFetchingContainers loading flag — survive Cancel and reappear on
the next open.

Additionally, the Azure Blob test-connection handler called
fetch("/api/connectors/azure_blob/test") with no AbortController.
Clicking Cancel while a test was in flight left isFetchingContainers
stuck at true until the underlying TCP connection timed out, keeping
the button locked on "Connecting…" on reopen.

Fix

1 — connector-cards.tsx: unmount on close

Render each SettingsDialog only while openDialog === descriptor.connectorType;
return null otherwise. The component unmounts on close, React destroys all
internal state, and every field and error message is fresh on the next open.
This also resolves the same latent stale-state bug in the S3 and IBM COS
dialogs at no extra cost, since they go through the same rendering loop.

2 — azure-blob/settings-dialog.tsx: AbortController on the test fetch

• A useRef<AbortController | null> tracks the currently in-flight test request.
• At the top of handleTestConnection, any prior call is aborted before a new
  controller is created — cancels a stuck request if the user clicks the button
  twice.
• signal: controller.signal is passed to fetch; AbortError is caught and
  swallowed silently (no error state set to the user).
• A useEffect cleanup aborts on unmount, so closing the dialog mid-request
  immediately cancels the network call rather than letting it run to TCP timeout.
• The finally block is guarded with testAbortRef.current === controller so
  that an aborted call's finally does not clear isFetchingContainers while a
  superseding request is still in flight (prevents spinner flicker).

Known tradeoff

Unmount-on-close skips the Radix exit animation — the dialog disappears
immediately rather than fading out. Intentional; correctness takes priority over
the transition.

Deferred follow-up

S3 (s3-settings-dialog.tsx) and IBM COS (ibm-cos/settings-dialog.tsx) both
use a mutateAsync + raw fetch sequence in their test paths. The raw fetch
portion is equally abortable, but adding AbortController to both is deferred
to keep this PR scoped to #2048.

Verification

• biome check and tsc --noEmit on the two changed files: no new warnings or
  errors vs. the baseline on main.
• Manual reproduction of all three symptoms from [Bug]: Azure Blog Storage Connector: "Azure Blob Storage Setup" dialog caches previous field state and error messages on cancel #2048 against a production
  container build of this branch (Azurite down): connection string, stale error
  message, and stuck loading state all confirmed fixed after Cancel + reopen.

Summary by CodeRabbit

• Bug Fixes
  • Improved connector settings dialogs so they close and reset cleanly.
  • Cancelled previous connection tests when a new test starts or the dialog closes.
  • Prevented cancelled requests from showing errors or incorrectly changing loading indicators.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 7ba0197b-95d8-4e5d-8c75-b84a2c55ca0e

📥 Commits

Reviewing files that changed from the base of the PR and between 7e036f0 and 4a2d325.

📒 Files selected for processing (2)

• frontend/app/settings/_components/connector-cards.tsx
• frontend/enhancements/connectors/azure-blob/settings-dialog.tsx

---

Walkthrough

Connector settings dialogs now unmount when closed. Azure Blob connection tests cancel prior or unmounted requests, suppress abort errors, and preserve loading state for the currently active request.

Changes

Connector dialog reliability

Layer / File(s)	Summary
Unmount closed connector dialogs frontend/app/settings/_components/connector-cards.tsx	Only the active connector’s settings dialog is mounted, with open={true} while rendered.
Cancel Azure Blob test requests frontend/enhancements/connectors/azure-blob/settings-dialog.tsx	AbortController cancels replaced or unmounted requests, ignores abort errors, and prevents stale requests from clearing loading state.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• langflow-ai/openrag#1974: Introduces the Azure Blob settings dialog whose test-connection flow is refined here.

Suggested reviewers: mfortman11, edwinjosechittilappilly

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main fix: resetting dialog state and aborting in-flight tests on cancel.
Linked Issues check	✅ Passed	The changes match #2048 by unmounting dialogs on close and aborting Azure Blob test requests to reset stale state.
Out of Scope Changes check	✅ Passed	The S3 and IBM COS dialog unmount behavior and Azure Blob abort cleanup are aligned with the stated PR objectives.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[hunterxtang]

Superseded by #2072 — re-landed on an in-repo branch so the secret-dependent checks (build-images, e2e) can run.