feat(opencode): bridge global OTel tracer for AI SDK telemetry

The existing Effect Otlp.layerJson (merged via #21387) instruments
Effect services but does not register a global OTel tracer provider.
The AI SDK's experimental_telemetry reads from the global provider,
so its spans were silently dropped.

This adds a lightweight BasicTracerProvider bridge that registers
globally when OTEL_EXPORTER_OTLP_ENDPOINT is set, using the same
endpoint and headers the Effect layer already reads. AI SDK spans
(ai.streamText, ai.toolCall, prompt/response content, token counts)
now export alongside Effect service spans to any OTLP/HTTP collector.

Also enables recordInputs/recordOutputs on both streamText and
generateObject call sites so full message content is captured as
span attributes.

Author: kitlangton

bun.lock

@@ -117,6 +117,11 @@
     "@opencode-ai/sdk": "workspace:*",
     "@opencode-ai/util": "workspace:*",
     "@openrouter/ai-sdk-provider": "2.4.2",
+    "@opentelemetry/api": "1.9.1",
+    "@opentelemetry/exporter-trace-otlp-http": "0.214.0",
+    "@opentelemetry/resources": "2.6.1",
+    "@opentelemetry/sdk-trace-base": "2.6.1",
+    "@opentelemetry/semantic-conventions": "1.40.0",
     "@opentui/core": "0.1.97",
     "@opentui/solid": "0.1.97",
     "@parcel/watcher": "2.5.1",

packages/opencode/package.json

@@ -13,6 +13,7 @@ import PROMPT_COMPACTION from "./prompt/compaction.txt"
 import PROMPT_EXPLORE from "./prompt/explore.txt"
 import PROMPT_SUMMARY from "./prompt/summary.txt"
 import PROMPT_TITLE from "./prompt/title.txt"
+import { Flag } from "@/flag/flag"
 import { Permission } from "@/permission"
 import { mergeDeep, pipe, sortBy, values } from "remeda"
 import { Global } from "@/global"
@@ -347,7 +348,9 @@ export namespace Agent {
 
           const params = {
             experimental_telemetry: {
-              isEnabled: cfg.experimental?.openTelemetry,
+              isEnabled: cfg.experimental?.openTelemetry || !!Flag.OTEL_EXPORTER_OTLP_ENDPOINT,
+              recordInputs: true,
+              recordOutputs: true,
               metadata: {
                 userId: cfg.username ?? "unknown",
               },

packages/opencode/src/agent/agent.ts

@@ -1,3 +1,4 @@
+import "./otel-bridge.js"
 import yargs from "yargs"
 import { hideBin } from "yargs/helpers"
 import { RunCommand } from "./cli/cmd/run"

packages/opencode/src/index.ts

@@ -0,0 +1,55 @@
+/**
+ * Registers a global OTel tracer provider so the AI SDK's
+ * `experimental_telemetry` spans are exported alongside Effect's own spans.
+ *
+ * Effect's Otlp.layerJson (in effect/oltp.ts) handles Effect-service tracing
+ * but does NOT register a global provider — the AI SDK only talks to the
+ * global one. This bridge fills the gap with a lightweight BasicTracerProvider.
+ *
+ * Import this module as the FIRST import in the entry point so the provider
+ * is registered before any AI SDK code runs.
+ */
+import { Flag } from "@/flag/flag"
+
+const endpoint = Flag.OTEL_EXPORTER_OTLP_ENDPOINT
+if (endpoint) {
+  const { trace } = await import("@opentelemetry/api")
+  const { BasicTracerProvider, BatchSpanProcessor } = await import("@opentelemetry/sdk-trace-base")
+  const { OTLPTraceExporter } = await import("@opentelemetry/exporter-trace-otlp-http")
+  const { resourceFromAttributes } = await import("@opentelemetry/resources")
+  const { ATTR_SERVICE_NAME, ATTR_SERVICE_VERSION } = await import("@opentelemetry/semantic-conventions")
+
+  const { CHANNEL, VERSION } = await import("@/installation/meta")
+
+  const provider = new BasicTracerProvider({
+    resource: resourceFromAttributes({
+      [ATTR_SERVICE_NAME]: "opencode",
+      [ATTR_SERVICE_VERSION]: VERSION,
+      "deployment.environment.name": CHANNEL === "local" ? "local" : CHANNEL,
+    }),
+    spanProcessors: [
+      new BatchSpanProcessor(
+        new OTLPTraceExporter({
+          url: `${endpoint.replace(/\/$/, "")}/v1/traces`,
+          headers: Flag.OTEL_EXPORTER_OTLP_HEADERS
+            ? Flag.OTEL_EXPORTER_OTLP_HEADERS.split(",").reduce(
+                (acc, x) => {
+                  const [key, ...rest] = x.split("=")
+                  acc[key] = rest.join("=")
+                  return acc
+                },
+                {} as Record<string, string>,
+              )
+            : undefined,
+        }),
+      ),
+    ],
+  })
+
+  trace.setGlobalTracerProvider(provider)
+
+  const shutdown = () => provider.shutdown().catch(() => {})
+  process.on("beforeExit", shutdown)
+  process.on("SIGINT", shutdown)
+  process.on("SIGTERM", shutdown)
+}

packages/opencode/src/otel-bridge.ts

@@ -385,7 +385,9 @@ export namespace LLM {
         ],
       }),
       experimental_telemetry: {
-        isEnabled: cfg.experimental?.openTelemetry,
+        isEnabled: cfg.experimental?.openTelemetry || !!Flag.OTEL_EXPORTER_OTLP_ENDPOINT,
+        recordInputs: true,
+        recordOutputs: true,
         metadata: {
           userId: cfg.username ?? "unknown",
           sessionId: input.sessionID,