TUI default in-process transport makes PluginInput.serverUrl report a fabricated localhost:4096 (plugins can't attach) #39561

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1. github-actions

   assigned

   kitlangton

   on Jul 29, 2026
2. github-actions commented on Jul 29, 2026

   

   github-actionsBot

   on Jul 29, 2026 – with GitHub Actions

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   This issue might be a duplicate of existing issues. Please check:

   • [FEATURE]: add ensureServer() to PluginInput for plugins that need an HTTP server #31821: Describes the same root cause — ctx.serverUrl returns a fabricated http://localhost:4096 when no HTTP server is bound in default TUI mode — and requests an ensureServer() API as a fix.
   • [FEATURE]: Export actual server URL as environment variable #9099: Also addresses the same underlying behavior (serverUrl fallback to localhost:4096 when no listener exists) and proposes exporting the actual server URL as an environment variable.

   Both issues stem from the same code path you've identified in plugin/index.ts. It may be worth coordinating with those threads, especially since your proposed fix (changing the fallback to http://opencode.internal) is complementary to the solutions discussed there.
3. rgillinlz commented on Jul 29, 2026

   

   rgillinlz

   on Jul 29, 2026

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   Attaching a ready-to-apply patch implementing the proposed fix, in case it's useful before a PR is up. Apply with:

   git am < plugin-serverurl-inprocess.patch

   Summary of the change (in packages/opencode/src/plugin/index.ts):

   • baseUrl fallback: "http://localhost:4096" → "http://opencode.internal"
   • serverUrl getter fallback: new URL("http://localhost:4096") → new URL("http://opencode.internal")

   Behavior-neutral for the plugin client (the in-process transport routes via Server.Default().app.fetch regardless of baseUrl host); it only makes the reported serverUrl honest so plugins can detect there's no external TCP server.

   plugin-serverurl-inprocess.patch

   From 6659527c98a067691684a188c292434f215eb690 Mon Sep 17 00:00:00 2001
   From: Robert Gillin <[email protected]>
   Date: Wed, 29 Jul 2026 13:16:53 -0700
   Subject: [PATCH] fix(plugin): report in-process placeholder in serverUrl when
    no HTTP listener is bound
   
   When the TUI runs with the default in-process transport (no --port/--hostname/--mdns),
   Server.url is undefined and PluginInput.serverUrl fell back to a fabricated
   http://localhost:4096, implying a reachable TCP server that does not exist. Plugins
   that dial ctx.serverUrl (e.g. cmux subagent-viewer's 'opencode attach') silently fail.
   
   Report the in-process placeholder http://opencode.internal instead, matching tui.ts
   and run.ts, so plugins can detect there is no external server. The in-process client
   routes via Server.Default().app.fetch regardless of baseUrl host, so this is
   behavior-neutral for the plugin client and only makes the reported URL honest.
   ---
    packages/opencode/src/plugin/index.ts | 11 +++++++++--
    1 file changed, 9 insertions(+), 2 deletions(-)
   
   diff --git a/packages/opencode/src/plugin/index.ts b/packages/opencode/src/plugin/index.ts
   index 1558c70..2b0a895 100644
   --- a/packages/opencode/src/plugin/index.ts
   +++ b/packages/opencode/src/plugin/index.ts
   @@ -139,8 +139,12 @@ const layer = Layer.effect(
            const { Server } = yield* Effect.promise(() => import("../server/server"))
    
            const serverUrl = Server.url
   +        // When no HTTP listener is bound (the default in-process TUI transport),
   +        // there is no reachable loopback URL. Report the in-process placeholder
   +        // ("http://opencode.internal") rather than a fabricated localhost:4096,
   +        // which would falsely imply a live TCP server that plugins can dial.
            const client = createOpencodeClient({
   -          baseUrl: serverUrl?.toString() ?? "http://localhost:4096",
   +          baseUrl: serverUrl?.toString() ?? "http://opencode.internal",
              directory: ctx.directory,
              headers: ServerAuth.headers(),
              ...(serverUrl ? {} : { fetch: async (...args) => Server.Default().app.fetch(...args) }),
   @@ -157,7 +161,10 @@ const layer = Layer.effect(
                },
              },
              get serverUrl(): URL {
   -            return Server.url ?? new URL("http://localhost:4096")
   +            // Reflect the bound listener when one exists; otherwise surface the
   +            // in-process placeholder so plugins can detect there is no external
   +            // TCP server instead of being handed a dead localhost:4096 URL.
   +            return Server.url ?? new URL("http://opencode.internal")
              },
              // @ts-expect-error
              $: typeof Bun === "undefined" ? undefined : Bun.$,
   -- 
   2.50.1 (Apple Git-155)
   
4. github-actions commented on Sep 29, 2026

   

   github-actionsBot

   on Sep 29, 2026 – with GitHub Actions

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   To stay organized issues are automatically closed after 60 days of no activity. If the issue is still relevant please open a new one.
5. github-actions

   closed this as not plannedon Sep 29, 2026