feat: add skill_used telemetry event

Tracks which skill is loaded and where it came from (`builtin`, `global`,
or `project`) with duration. Wrapped in try/catch — cannot break skill
loading. Docs table updated.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: suryaiyer95

docs/docs/configure/telemetry.md

@@ -33,6 +33,7 @@ We collect the following categories of events:
 | `error_recovered` | Successful recovery from a transient error (error type, strategy, attempt count) |
 | `mcp_server_census` | MCP server capabilities after connect (tool and resource counts — no tool names) |
 | `context_overflow_recovered` | Context overflow is handled (strategy) |
+| `skill_used` | A skill is loaded (skill name and source — `builtin`, `global`, or `project` — no skill content) |
 | `core_failure` | A tool failure occurs — error category, error message (truncated to 500 chars), and PII-masked arguments (string literals in SQL replaced with `?`, sensitive keys like `password`/`token`/`secret` fully redacted) |
 
 Each event includes a timestamp, anonymous session ID, and the CLI version.

packages/drivers/src/sqlserver.ts

@@ -7,7 +7,6 @@ import type { ConnectionConfig, Connector, ConnectorResult, SchemaColumn } from
 export async function connect(config: ConnectionConfig): Promise<Connector> {
   let mssql: any
   try {
-    // @ts-expect-error — optional dependency, loaded at runtime
     mssql = await import("mssql")
     mssql = mssql.default || mssql
   } catch {

packages/opencode/src/altimate/telemetry/index.ts

@@ -332,6 +332,15 @@ export namespace Telemetry {
         has_ssh_tunnel: boolean
         has_keychain: boolean
       }
+    | {
+        type: "skill_used"
+        timestamp: number
+        session_id: string
+        message_id: string
+        skill_name: string
+        skill_source: "builtin" | "global" | "project"
+        duration_ms: number
+      }
     | {
         type: "core_failure"
         timestamp: number

packages/opencode/src/tool/skill.ts

@@ -9,8 +9,16 @@ import { iife } from "@/util/iife"
 import { Fingerprint } from "../altimate/fingerprint"
 import { Config } from "../config/config"
 import { selectSkillsWithLLM } from "../altimate/skill-selector"
+import { Telemetry } from "../altimate/telemetry"
+import os from "os"
 
 const MAX_DISPLAY_SKILLS = 50
+
+function classifySkillSource(location: string): "builtin" | "global" | "project" {
+  if (location.includes("node_modules") || location.includes(".altimate/builtin")) return "builtin"
+  if (location.startsWith(os.homedir())) return "global"
+  return "project"
+}
 // altimate_change end
 
 export const SkillTool = Tool.define("skill", async (ctx) => {
@@ -83,6 +91,7 @@ export const SkillTool = Tool.define("skill", async (ctx) => {
     description,
     parameters,
     async execute(params: z.infer<typeof parameters>, ctx) {
+      const startTime = Date.now()
       // altimate_change start - use upstream Skill.get() for exact name lookup
       const skill = await Skill.get(params.name)
 
@@ -122,6 +131,20 @@ export const SkillTool = Tool.define("skill", async (ctx) => {
         return arr
       }).then((f) => f.map((file) => `<file>${file}</file>`).join("\n"))
 
+      try {
+        Telemetry.track({
+          type: "skill_used",
+          timestamp: Date.now(),
+          session_id: ctx.sessionID,
+          message_id: ctx.messageID,
+          skill_name: skill.name,
+          skill_source: classifySkillSource(skill.location),
+          duration_ms: Date.now() - startTime,
+        })
+      } catch {
+        // Telemetry must never break skill loading
+      }
+
       return {
         title: `Loaded skill: ${skill.name}`,
         output: [