fix(dev): use 127.0.0.1 instead of localhost for dev server (IPv6 resolution) by hnbdr · Pull Request #1589 · Zoo-Code-Org/Zoo-Code

hnbdr · 2026-09-10T12:11:39Z

Closes: #1588

Description

On systems where localhost resolves to ::1 before 127.0.0.1, the dev-mode webview fails to load: the axios.get("http://localhost:<port>") health check in getHMRHtmlContent() never reaches the Vite dev server, so Zoo Code shows "Local development server is not running..." even though the server is up.

Fix is to stop relying on the ambiguous localhost name in the dev loop and pin both sides to IPv4:

src/core/webview/ClineProvider.ts: localServerUrl and the injected @react-refresh import URL now use 127.0.0.1 instead of localhost. This also keeps the CSP entries (script-src/connect-src/style-src, which are derived from localServerUrl) consistent with what the webview actually loads.
webview-ui/vite.config.ts: bind the dev server explicitly with host: "127.0.0.1", keep hmr: true (HMR now derives host/port from the server config instead of a separate hmr.host: "localhost"), pin port: 5173, and move the ws.protocol: "ws" setting under server.ws since HMR is no longer an object.

Design note: choosing 127.0.0.1 over ::1 matches the existing 0.0.0.0 fallback already present in the CSP and is deterministic on Windows where Node 17+ uses verbatim DNS ordering.

Test Procedure

pnpm --dir src exec eslint --max-warnings=0 core/webview/ClineProvider.ts and webview lint — clean.
tsc -b in webview-ui — clean.
Full pnpm lint and pnpm check-types (turbo, all packages) via pre-commit/pre-push hooks — pass.
Manual: on an affected machine (Resolve-DnsName localhost returns AAAA ::1 first), run pnpm dev + launch the extension host, open the sidebar — the webview loads with working HMR and no "server is not running" error. Also verified the normal IPv4-first path still works.

Pre-Submission Checklist

Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
Scope: My changes are focused on the linked issue (one major feature/fix per PR).
Self-Review: I have performed a thorough self-review of my code.
Testing: New and/or updated tests have been added to cover my changes (if applicable).
Visual Snapshot (UI changes only): N/A — dev-server wiring only, no rendered UI change.
Documentation Impact: I have considered if my changes require documentation updates (see "Documentation Updates" section below).
Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Visual Snapshots

N/A — no user-facing rendered state changes; this only affects the dev-mode bootstrap.

Videos (interaction / animation only)

N/A.

Documentation Updates

No documentation updates are required.

Additional Notes

No unit test added: the touched code path is dev-only bootstrap (getHMRHtmlContent + Vite server config) with no existing test harness around it; coverage is the manual repro in #1588.

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hnbdr

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src/core/webview/__tests__/ClineProvider.spec.ts (1)

3-3: LGTM!

Also applies to: 704-714, 716-747

📝 Summary

Summary by CodeRabbit

Bug Fixes
- Development-mode webviews now use 127.0.0.1 consistently for the local development server, hot-reload connections, and refresh runtime, avoiding address mismatches.
- The development server continues to use port 5173, and webviews continue to fall back to production content when the development server is unavailable.

Walkthrough

The Vite development server and webview use 127.0.0.1 for HMR. Tests cover the unavailable-server fallback and generated development URLs when the server is reachable.

Changes

Development Webview HMR

Layer / File(s)	Summary
Configure and verify IPv4 HMR URLs `webview-ui/vite.config.ts`, `src/core/webview/ClineProvider.ts`, `src/core/webview/__tests__/ClineProvider.spec.ts`	Vite binds to `127.0.0.1` on port `5173` and sets the WebSocket protocol to `ws`. `ClineProvider` uses `127.0.0.1` for the server probe, script URL, CSP entries, and React Refresh import. Tests cover the unavailable-server fallback and generated URLs when the server is reachable.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to ff2ea

No actionable merge-blocking risk remains in the supplied change; it is mergeable after normal checks.

Architecture Summary

Architecture risk: 🔵 Low · up to ff2ea

The change affects 2 systems.

Changed systems: src, webview-ui

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

observed — src (service) was modified; 2 changed files map to changed impact.
observed — webview-ui (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

observed — Modified behavior in src/core/webview/ClineProvider.ts: The development server URL changes from localhost to 127.0.0.1 for the Vite availability check, script URL, and CSP entries that use localServerUrl.
observed — Modified behavior in src/core/webview/ClineProvider.ts: The React refresh runtime import now targets 127.0.0.1 instead of localhost.
observed — Modified behavior in webview-ui/vite.config.ts: The server now enables HMR with a boolean and sets the bind host to 127.0.0.1, port to 5173, and WebSocket configuration to protocol ws; the previous HMR host override of localhost is removed.
observed — Modified behavior in src/core/webview/tests/ClineProvider.spec.ts: Adds the fs import used by the development-server test to control the .vite-port existence check.

🚥 Pre-merge checks | ✅ 7 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Lifecycle Resource Cleanup	⚠️ Warning	The added reachable-server test creates a `ClineProvider`, calls `resolveWebviewView`, and never disposes that provider. `ClineProvider` adds each instance to the static `activeInstances` set, and `re…	Dispose the provider in the test cleanup path, such as by keeping the new instance in a local variable and awaiting `hmrProvider.dispose()` in the `finally` block. Apply the same cleanup to any provider instance that is replaced during thes…

✅ Passed checks (7 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Issue `#1588` requires a reliable IPv4 development loop. `ClineProvider` now uses `127.0.0.1` for the health check and React Refresh URL. Vite now binds to `127.0.0.1` and configures `ws` HMR. The added…
Out of Scope Changes check	✅ Passed	All changed source code addresses issue `#1588`. The test changes isolate the default Vite port and restore test state while verifying the reachable and unavailable development-server paths. No unrelate…
Regression Evidence	✅ Passed	The PR adds focused behavior coverage for the changed HMR path. The development-mode reachable-server test forces the default port, verifies the probe calls `http://127.0.0.1:5173`, and checks the gen…
Security Boundaries	✅ Passed	PASS. The changed runtime path only replaces the development host with the fixed value `127.0.0.1` in `ClineProvider.getHMRHtmlContent()` and binds Vite to that host. It does not add secret or PII han…
Persistence Integrity	✅ Passed	PASS — The pull request changes dev-server URLs, Vite binding/HMR settings, and test isolation. It does not change a persistence write, default propagation path, rollback path, or operation awaiting. …
Title check	✅ Passed	The title clearly and concisely describes the main change: replacing localhost with 127.0.0.1 for the development server to avoid IPv6 resolution issues.
Description check	✅ Passed	The description includes the linked issue, implementation details, test procedure, checklist, snapshot and documentation sections, and reviewer notes. It is mostly complete and directly supports the p…

Full details: Lifecycle Resource Cleanup

Explanation

The added reachable-server test creates a ClineProvider, calls resolveWebviewView, and never disposes that provider. ClineProvider adds each instance to the static activeInstances set, and resolveWebviewView registers listeners. The test finally block restores only the fs.existsSync spy and environment variable. After the test, the provider and its resources remain retained, and repeated test runs accumulate them.

Resolution

Dispose the provider in the test cleanup path, such as by keeping the new instance in a local variable and awaiting hmrProvider.dispose() in the finally block. Apply the same cleanup to any provider instance that is replaced during these tests, or add an afterEach that disposes the current provider without overwriting undisposed instances.

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github-actions · 2026-09-10T12:11:52Z

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codecov · 2026-09-10T12:19:29Z

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Inline comments:
In `@src/core/webview/__tests__/ClineProvider.spec.ts`:
- Around line 710-712: In the test that calls resolveWebviewView, clear the
axios.get mock before the call and assert it was called with the dev-server
health-check URL, http://127.0.0.1:5173. Leave the existing HTML assertions
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webview-ui/vite.config.ts (1)

124-127: LGTM!

src/core/webview/ClineProvider.ts (1)

1546-1546: LGTM!

Also applies to: 1585-1585

src/core/webview/__tests__/ClineProvider.spec.ts (1)

667-667: LGTM!

Also applies to: 669-669, 672-672, 674-674

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In `@src/core/webview/__tests__/ClineProvider.spec.ts`:
- Line 718: Update the test around getHMRHtmlContent so it controls the
port-file read or explicitly establishes the default-port branch before
asserting the fixed URL. Ensure an independently present src/.vite-port cannot
change the expected probe URL.
- Around line 726-728: Wrap the test body that changes
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…IPv6 resolution issues

…th-check URL

…ort file and restore env in finally

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hnbdr marked this pull request as ready for review September 10, 2026 12:42

hnbdr requested review from JamesRobert20, edelauna, hannesrudolph, navedmerchant and taltas as code owners September 10, 2026 12:42

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fix(dev): use 127.0.0.1 instead of localhost for dev server to avoid …

ae6117b

…IPv6 resolution issues

test(webview): assert HMR html targets the 127.0.0.1 dev server

6455de7

test(webview): assert the dev-server probe targets the 127.0.0.1 heal…

f0d65cc

…th-check URL

test(webview): isolate the dev-server probe test from a stray .vite-p…

2e61acb

…ort file and restore env in finally

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fix(dev): use 127.0.0.1 instead of localhost for dev server (IPv6 resolution) - #1589

fix(dev): use 127.0.0.1 instead of localhost for dev server (IPv6 resolution)#1589
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