diff --git a/packages/opencode/src/altimate/telemetry/index.ts b/packages/opencode/src/altimate/telemetry/index.ts
index b2b0e7103..ac275a861 100644
--- a/packages/opencode/src/altimate/telemetry/index.ts
+++ b/packages/opencode/src/altimate/telemetry/index.ts
@@ -1198,6 +1198,10 @@ export namespace Telemetry {
   let flushTimer: ReturnType<typeof setInterval> | undefined
   let userEmail = ""
   let machineId = ""
+  // Where this serve process was launched from ("ide" when spawned by an
+  // editor extension, "" for CLI/TUI). Stamped onto every event so analytics
+  // can attribute sessions to IDE vs terminal usage.
+  let launchSurface = ""
   let sessionId = ""
   let projectId = ""
   let appInsights: AppInsightsConfig | undefined
@@ -1228,6 +1232,7 @@ export namespace Telemetry {
         cli_version: Installation.VERSION,
         project_id: fields.project_id ?? projectId,
         ...(machineId && { machine_id: machineId }),
+        ...(launchSurface && { launch_surface: launchSurface }),
       }
       const measurements: Record<string, number> = {}
 
@@ -1319,6 +1324,13 @@ export namespace Telemetry {
       } catch {
         // Account unavailable — proceed without user ID
       }
+      // Set by the IDE extension when it spawns `altimate serve`; absent for
+      // direct CLI/TUI invocations. Normalize casing/whitespace and restrict to
+      // a known set so a stray env value can't inflate the launch_surface
+      // dimension's cardinality. New surfaces must be added to KNOWN_LAUNCH_SURFACES.
+      const KNOWN_LAUNCH_SURFACES = new Set(["ide", "cli", "tui"])
+      const rawLaunchSurface = (process.env.ALTIMATE_LAUNCH_SURFACE ?? "").trim().toLowerCase()
+      launchSurface = KNOWN_LAUNCH_SURFACES.has(rawLaunchSurface) ? rawLaunchSurface : ""
       try {
         const machineIdPath = path.join(os.homedir(), ".altimate", "machine-id")
         try {
@@ -1449,6 +1461,7 @@ export namespace Telemetry {
     sessionId = ""
     projectId = ""
     machineId = ""
+    launchSurface = ""
     initPromise = undefined
     initDone = false
   }
diff --git a/packages/opencode/test/telemetry/telemetry.test.ts b/packages/opencode/test/telemetry/telemetry.test.ts
index 2f0d2dce8..03f8153b9 100644
--- a/packages/opencode/test/telemetry/telemetry.test.ts
+++ b/packages/opencode/test/telemetry/telemetry.test.ts
@@ -596,6 +596,82 @@ describe("telemetry.toAppInsightsEnvelopes (indirect)", () => {
     }
   })
 
+  test("launch_surface is stamped on every event when ALTIMATE_LAUNCH_SURFACE is set", async () => {
+    const origSurface = process.env.ALTIMATE_LAUNCH_SURFACE
+    process.env.ALTIMATE_LAUNCH_SURFACE = "ide"
+    const { fetchCalls, cleanup } = await initWithMockedFetch()
+    try {
+      Telemetry.track({ type: "session_start", timestamp: 1700000000000, session_id: "sess-ide" })
+      await Telemetry.flush()
+
+      expect(fetchCalls.length).toBeGreaterThan(0)
+      const envelopes = JSON.parse(fetchCalls[0].body)
+      expect(envelopes.length).toBeGreaterThan(0)
+      expect(envelopes[0].data.baseData.properties.launch_surface).toBe("ide")
+    } finally {
+      cleanup()
+      if (origSurface !== undefined) process.env.ALTIMATE_LAUNCH_SURFACE = origSurface
+      else delete process.env.ALTIMATE_LAUNCH_SURFACE
+    }
+  })
+
+  test("launch_surface is omitted when ALTIMATE_LAUNCH_SURFACE is unset (CLI/TUI)", async () => {
+    const origSurface = process.env.ALTIMATE_LAUNCH_SURFACE
+    delete process.env.ALTIMATE_LAUNCH_SURFACE
+    const { fetchCalls, cleanup } = await initWithMockedFetch()
+    try {
+      Telemetry.track({ type: "session_start", timestamp: 1700000000000, session_id: "sess-cli" })
+      await Telemetry.flush()
+
+      expect(fetchCalls.length).toBeGreaterThan(0)
+      const envelopes = JSON.parse(fetchCalls[0].body)
+      expect(envelopes.length).toBeGreaterThan(0)
+      expect(envelopes[0].data.baseData.properties.launch_surface).toBeUndefined()
+    } finally {
+      cleanup()
+      if (origSurface !== undefined) process.env.ALTIMATE_LAUNCH_SURFACE = origSurface
+      else delete process.env.ALTIMATE_LAUNCH_SURFACE
+    }
+  })
+
+  test("launch_surface normalizes casing and surrounding whitespace", async () => {
+    const origSurface = process.env.ALTIMATE_LAUNCH_SURFACE
+    process.env.ALTIMATE_LAUNCH_SURFACE = "  IDE "
+    const { fetchCalls, cleanup } = await initWithMockedFetch()
+    try {
+      Telemetry.track({ type: "session_start", timestamp: 1700000000000, session_id: "sess-norm" })
+      await Telemetry.flush()
+
+      expect(fetchCalls.length).toBeGreaterThan(0)
+      const envelopes = JSON.parse(fetchCalls[0].body)
+      expect(envelopes.length).toBeGreaterThan(0)
+      expect(envelopes[0].data.baseData.properties.launch_surface).toBe("ide")
+    } finally {
+      cleanup()
+      if (origSurface !== undefined) process.env.ALTIMATE_LAUNCH_SURFACE = origSurface
+      else delete process.env.ALTIMATE_LAUNCH_SURFACE
+    }
+  })
+
+  test("launch_surface drops unrecognized values to keep the dimension low-cardinality", async () => {
+    const origSurface = process.env.ALTIMATE_LAUNCH_SURFACE
+    process.env.ALTIMATE_LAUNCH_SURFACE = "totally-bogus"
+    const { fetchCalls, cleanup } = await initWithMockedFetch()
+    try {
+      Telemetry.track({ type: "session_start", timestamp: 1700000000000, session_id: "sess-bogus" })
+      await Telemetry.flush()
+
+      expect(fetchCalls.length).toBeGreaterThan(0)
+      const envelopes = JSON.parse(fetchCalls[0].body)
+      expect(envelopes.length).toBeGreaterThan(0)
+      expect(envelopes[0].data.baseData.properties.launch_surface).toBeUndefined()
+    } finally {
+      cleanup()
+      if (origSurface !== undefined) process.env.ALTIMATE_LAUNCH_SURFACE = origSurface
+      else delete process.env.ALTIMATE_LAUNCH_SURFACE
+    }
+  })
+
   test("numeric fields go to measurements, string fields go to properties", async () => {
     const { fetchCalls, cleanup } = await initWithMockedFetch()
     try {