Add reconnecting websocket class and use it in CoderApi#654

EhabY · 2025-11-17T15:27:33Z

Closes#595

This PR implements a reconnecting WebSocket with exponential backoff that automatically uses the most up-to-date authentication information.

Why not use existing packages?

Third-party reconnecting WebSocket packages (e.g., reconnecting-websocket) were considered but don't meet our requirements:

Most packages are stale/unmaintained
None support custom async authentication methods (we pass different options based on header commands or session tokens)
Limited flexibility for future authentication expansion

Additional features:

Automatic reconnection when session tokens or host values change, ensuring we always use current authentication info
Potential future enhancement: Reconnect on proxy/auth/header setting changes (deferred for now)

src/websocket/reconnectingWebSocket.ts

jakehwll · 2025-11-21T10:24:04Z

src/websocket/reconnectingWebSocket.ts

+// Don't reconnect on normal closure
+if(event.code===1000||event.code===1001){
+return;
+}


nit: magic numbers are magic.. const these?

DanielleMaywood · 2025-11-21T10:19:18Z

src/api/agentMetadataHelper.ts

+if(watcher.error!==undefined){
+watcher.error=undefined;
+onChange.fire(null);
+}


What is the context behind this change?

If we reach this place in the code that means we didn't encounter an error while parsing the message and thus we have a valid message so we clear the error (if any). The clients of this method usually display the error (if it exists) before attempting to access the value

DanielleMaywood · 2025-11-21T10:26:25Z

src/websocket/reconnectingWebSocket.ts

+initialBackoffMs: options.initialBackoffMs??250,
+maxBackoffMs: options.maxBackoffMs??30000,
+jitterFactor: options.jitterFactor??0.1,


How did we come up with these default values? This is non-blocking, just curious 😄

Oh very random and some AI "researched" values hahaha

src/websocket/reconnectingWebSocket.ts

DanielleMaywood · 2025-11-21T10:29:01Z

src/websocket/reconnectingWebSocket.ts

+wasClean: true,
+type: "close",
+target: this.#currentSocket,
+}asCloseEvent);


Does this need as CloseEvent? Could we make use of satisfies?

Thanks for pointing this out, this exposed a bigger issue with types, I made sure to narrow the types in eventStreamConnection so it's reflects the information we have and we don't do some nasty casting

src/websocket/reconnectingWebSocket.ts

DanielleMaywood

I'm happy with this change, thanks for addressing the types issue 🙏

…n socket creation

* Better error handling for HTTP errors * Refactor magic numbers * Use strict types and avoid casting

EhabY force-pushed the reconnecting-websockets branch 4 times, most recently from f10c59b to 656bb4cCompare November 21, 2025 09:49

EhabY commented Nov 21, 2025
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src/websocket/reconnectingWebSocket.ts Outdated Show resolvedHide resolved

mtojek requested a review from DanielleMaywood November 21, 2025 10:19

jakehwll reviewed Nov 21, 2025
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src/websocket/reconnectingWebSocket.ts Outdated Show resolvedHide resolved

jakehwll reviewed Nov 21, 2025
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DanielleMaywood reviewed Nov 21, 2025
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EhabY requested a review from DanielleMaywood November 21, 2025 13:33

DanielleMaywood approved these changes Nov 21, 2025
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jakehwll approved these changes Nov 24, 2025
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EhabY added 6 commits November 25, 2025 12:34

Add reconnecting websocket class and use it in CoderApi
f298798

Fix an issue with changing host + Fix an issue with catching errors o…
bd24201
…n socket creation

Improve logging messages
6f6af73

Various improvements to reconnecting websockets + More tests
05c2357

Address review comments
19d8e6f
* Better error handling for HTTP errors * Refactor magic numbers * Use strict types and avoid casting

Add changelog entry
55b793b

EhabY force-pushed the reconnecting-websockets branch from eec4c99 to 55b793bCompare November 25, 2025 09:57

EhabY merged commit d5c3cc0 into coder:mainNov 25, 2025
3 checks passed

Add reconnecting websocket class and use it in CoderApi#654

Add reconnecting websocket class and use it in CoderApi #654

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EhabY commented Nov 17, 2025•
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