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Merged
kevoconnell merged 1 commit into from
Sep 21, 2026
Merged

Log why an MCP server was unavailable, not just that it was #51

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7 changes: 6 additions & 1 deletion packages/opencode/src/mcp/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -399,7 +399,12 @@ const layer = Layer.effect(

if (!mcpClient) {
if (status.status !== "connected" && status.status !== "disabled") {
yield* Effect.logWarning("server unavailable", { key, type: mcp.type, status: status.status })
yield* Effect.logWarning("server unavailable", {
key,
type: mcp.type,
status: status.status,
error: "error" in status ? status.error : undefined,

@cubic-dev-ai cubic-dev-ai Bot Sep 21, 2026

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P2: The newly logged status.error is raw error.message from the connect path. For local servers this can embed subprocess/stderr text, and for remote servers it can embed URL or server-returned content, so a server or misconfigured URL containing credentials would now dump them into logs. Mask/sanitize the error string (strip URLs' userinfo, cap length) before logging, or verify none of these transports place credentials in error.message.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At packages/opencode/src/mcp/index.ts, line 406:

<comment>The newly logged `status.error` is raw `error.message` from the connect path. For local servers this can embed subprocess/stderr text, and for remote servers it can embed URL or server-returned content, so a server or misconfigured URL containing credentials would now dump them into logs. Mask/sanitize the error string (strip URLs' userinfo, cap length) before logging, or verify none of these transports place credentials in `error.message`.</comment>

<file context>
@@ -399,7 +399,12 @@ const layer = Layer.effect(
+              key,
+              type: mcp.type,
+              status: status.status,
+              error: "error" in status ? status.error : undefined,
+            })
           }
</file context>

@cubic-dev-ai cubic-dev-ai Bot Sep 21, 2026

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P3: For the needs_auth status the log line now carries an error: undefined field, which is noise in exactly the log this PR is improving. Spread the field conditionally so it is absent rather than undefined when the status has no error.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At packages/opencode/src/mcp/index.ts, line 406:

<comment>For the `needs_auth` status the log line now carries an `error: undefined` field, which is noise in exactly the log this PR is improving. Spread the field conditionally so it is absent rather than `undefined` when the status has no error.</comment>

<file context>
@@ -399,7 +399,12 @@ const layer = Layer.effect(
+              key,
+              type: mcp.type,
+              status: status.status,
+              error: "error" in status ? status.error : undefined,
+            })
           }
</file context>
Suggested change
error: "error" in status ? status.error : undefined,
...("error" in status ? { error: status.error } : {}),

})
}
return { status } satisfies CreateResult
}
Expand Down
26 changes: 25 additions & 1 deletion packages/opencode/test/mcp/lifecycle.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ import {
type Tool,
} from "@modelcontextprotocol/sdk/types.js"
import { LayerNode } from "@opencode-ai/core/effect/layer-node"
import { Cause, Effect, Exit } from "effect"
import { Cause, Effect, Exit, Logger } from "effect"
import type { MCP as MCPNS } from "../../src/mcp/index"
import { MCP } from "../../src/mcp/index"
import { McpOAuthCallback } from "../../src/mcp/oauth-callback"
Expand Down Expand Up @@ -493,6 +493,30 @@ it.instance("unavailable remote server is marked failed without tools", () =>
}),
)

it.instance("unavailable remote server surfaces the underlying error in the log", () =>
Effect.gen(function* () {
const server = yield* Effect.acquireRelease(
Effect.sync(() => Bun.serve({ port: 0, fetch: () => new Response("unavailable", { status: 503 }) })),
(http) => Effect.promise(() => http.stop(true)),
)
const mcp = yield* MCP.Service
const captured: Array<unknown> = []
const capture = Logger.make((options) => {
captured.push(options.message)
})

yield* mcp
.add("unlogged", remote(server.url.toString(), 500))
.pipe(Effect.provide(Logger.layer([capture], { mergeWithExisting: true })))

const logged = captured.find((item) => Array.isArray(item) && item[0] === "server unavailable")
expect(logged).toBeDefined()
if (!Array.isArray(logged)) return
const fields: unknown = logged[1]
expect(fields).toMatchObject({ status: "failed", error: expect.any(String) })
}),
)

it.instance("tools() prefixes sanitized server and tool names", () =>
Effect.gen(function* () {
const server = yield* lifecycleServer({ capabilities: { tools: {} } })
Expand Down
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