Anonymous usage telemetry

Status: implemented — ingest Worker (telemetry-worker/), client (src/telemetry/), codegraph telemetry CLI, MCP + installer wiring, TELEMETRY.md. Pending: Worker deploy

DNS, release. Scope: public codegraph engine (CLI + MCP server + installer)

CodeGraph is a local-first tool whose whole pitch is "your code never leaves your machine." Telemetry has to be designed so that sentence stays true and provable: a short, auditable list of anonymous counters, documented field-by-field, easy to turn off, and impossible to grow quietly. This doc is the contract; TELEMETRY.md (repo root, user-facing) restates it and the implementation must never collect anything not listed there.

Goals

Answer, in aggregate and anonymously:

How many machines actively use codegraph (daily/weekly), and how does that change?
Which agents drive usage (Claude Code, Cursor, Codex, opencode, …) — via MCP clientInfo.
Which install targets people pick, local vs global, fresh vs upgrade.
Which MCP tools and CLI commands get used, how often, and how often they error.
Which languages people index (prioritize extractor/framework work by real usage).
Version adoption speed, OS/arch/Node mix, native-vs-wasm SQLite backend share.

Non-goals / never collected

No source code, ever. No file paths, file names, repo names, symbol names, query strings, search terms, or anything derived from the contents of an indexed project.
No IP addresses (stripped at the edge; storage disabled at the backend too).
No hardware fingerprinting — the machine ID is a random UUID, not derived from anything.
No per-keystroke / per-call event stream — usage is aggregated locally into daily rollups before anything is sent.
No telemetry from the codegraph-pro fork (see "codegraph-pro rule" below).

Principles

The schema is the allowlist. Client sends only the events below; the ingest Worker validates against the same allowlist and drops anything else. Adding a field = PR that edits this doc + TELEMETRY.md + the Worker allowlist together.
Telemetry may never cost the user anything: zero added latency on the MCP tool-call hot path (the repo's core invariant), zero new npm dependencies (global fetch, Node ≥18), zero bytes on stdout (stdio is the MCP protocol channel), zero retries, zero error noise. Every failure mode is silence.
Off is off. When disabled, no process opens a socket to the telemetry endpoint — not even an "opted out" ping.
First-party endpoint. Clients only ever talk to telemetry.getcodegraph.com. The URL baked into a published npm version POSTs there forever, so the domain must be ours; the backend behind it can change without a client release.

Events

Common envelope on every batch (computed once per process):

field	example	notes
`machine_id`	`b3a8…` (UUIDv4)	random, minted at first run, stored in global config
`codegraph_version`	`0.9.12`	from package.json
`os` / `arch`	`darwin` / `arm64`	`process.platform` / `process.arch`
`node_major`	`22`	major only
`ci`	`false`	`CI` env var present
`schema_version`	`1`	bump when the schema changes

Event types:

install — one per installer run. Props: targets (e.g. ["claude","cursor"]), scope (local/global), kind (fresh/upgrade/reinstall), sqlite_backend (native/wasm).
index — one per full index (init/index, not per sync). Props: languages (names only, e.g. ["typescript","go"]), file_count_bucket (<100, 100-1k, 1k-10k, 10k+), duration_bucket (<10s, 10-60s, 1-5m, 5m+), sqlite_backend.
usage_rollup — the workhorse. One event per (day, kind, name) per machine, aggregated locally. Props: kind (mcp_tool/cli_command), name (e.g. codegraph_explore, affected), count, error_count, and for MCP: client_name/client_version from the initialize handshake (src/mcp/session.ts case 'initialize' — plumbing to add; currently unread).
uninstall — one per uninstall/uninit run (churn signal). Props: targets.

Volume math: rollups mean monthly events ≈ active machines × active days × distinct tools used (single digits) — the PostHog free tier (1M events/mo) covers tens of thousands of MAU. There is no per-call event by design.

Events are sent as PostHog anonymous events ($process_person_profile: false): cheaper, no person profiles, unique-machine counts still work on distinct_id = machine_id. Revisit only if retention tooling demands profiles.

Consent & controls

Resolution order (first match wins):

DO_NOT_TRACK=1 (community standard — always honored) → off
CODEGRAPH_TELEMETRY=0|1 → forced off/on for that process
Global config ~/.codegraph/telemetry.json → stored user choice
Default: on, gated by the first-run notice below

Surfaces:

Installer (interactive): a visible clack toggle in the existing prompt flow — "Share anonymous usage data? (no code, paths, or names — see TELEMETRY.md)" — default yes. Choice persisted with consent_source: "installer". Re-runs/upgrades respect the stored choice and don't re-ask.
Headless paths (npx codegraph init, MCP server — no TTY, never prompt): right before the first actual send (recording only buffers locally and stays silent — so the installer's explicit toggle always precedes any notice), print one line to stderr and record first_run_notice_shown: codegraph collects anonymous usage stats (no code or paths) — "codegraph telemetry off" or CODEGRAPH_TELEMETRY=0 disables. Details: TELEMETRY.md
CLI: codegraph telemetry status|on|off (status prints the machine ID, current state, and what decided it). Deleting ~/.codegraph/telemetry.json resets everything, including the machine ID.

~/.codegraph/telemetry.json:

{
  "enabled": true,
  "machine_id": "uuid-v4",
  "consent_source": "installer | default-notice | cli",
  "first_run_notice_shown": true,
  "updated_at": "2026-06-12T00:00:00Z"
}

(~/.codegraph/ is new — today nothing global exists. Coexists by filename if a user ever indexes $HOME itself, since per-project data lives in <project>/.codegraph/ with fixed other filenames.)

Client architecture

New module src/telemetry/ (single small module, no deps):

Counters in memory — recording a tool call/CLI command is an in-memory increment. Nothing on the hot path touches disk or network. MCP tool handlers call telemetry.count('mcp_tool', name, ok) and move on.
Buffer — counters persist (debounced, async) to ~/.codegraph/telemetry-queue.jsonl. Hard cap ~256 KB; on overflow drop oldest lines. Corrupt buffer → truncate, never throw.
Flush — many CLI actions end via process.exit(), where beforeExit never fires and async sends die, so the design is: a tiny synchronous append on process.on('exit') persists in-memory deltas (survives process.exit), and actual network sends happen opportunistically — at the start of long-running commands (init/index/sync/ uninit/upgrade), on an unref'd interval in the long-lived MCP server/daemon, and awaited-with-cap at the end of install/init/index/uninit where a second is invisible. Sends POST completed-day rollups + lifecycle events to https://telemetry.getcodegraph.com/v1/events with AbortSignal.timeout(1500), fire-and-forget: any response (or none) is final — no retry, no error surfaced. The queue is claimed by atomic rename so concurrent processes can't double-send (a crashed sender's claim merges back after an hour). CODEGRAPH_TELEMETRY_DEBUG=1 echoes payloads to stderr for development.
Offline / air-gapped: flush fails silently, buffer stays within cap, steady state is a bounded file and zero noise.

Ingest endpoint (Cloudflare Worker)

telemetry.getcodegraph.com → small Worker living at telemetry-worker/ in this repo — public on purpose, so anyone can audit exactly what the endpoint stores. It ships nowhere with the npm package (excluded by the files allowlist):

POST /v1/events: validate against the event/property allowlist (drop unknown events, strip unknown props), enforce sane sizes, never forward or log the client IP (drop CF-Connecting-IP), light per-machine_id rate limit so abuse can't burn the ingest cap, forward to https://us.i.posthog.com/batch/ with the project key from a Worker secret. Responds 204 on accept (including events dropped by the allowlist) and honest 4xx for malformed/oversized/rate-limited requests — the client treats every response as final and never retries.
Backend today: PostHog Cloud US, free plan, "discard client IP" enabled, GeoIP disabled, autocapture/replay/heatmaps/web-vitals all off. The Worker is the seam: swapping the backend later is a Worker change, not a client release.

codegraph-pro rule (do not lose this in upstream merges)

The private codegraph-pro fork ships inside customer containers whose guarantee is "nothing leaves the box" — including telemetry. In the fork, telemetry must be default-off and not enableable by the installer (compile-time constant or stripped module), and the container sets CODEGRAPH_TELEMETRY=0 as belt-and-braces. This rule lives in the fork's CLAUDE.md and must survive every upstream merge.

Rollout

This doc + repo-root TELEMETRY.md (user-facing field-by-field list) + README section.
Worker + DNS live first (so the first shipping client never 404s), PostHog dashboards: weekly active machines, installs by target, usage by tool × client, version adoption, languages indexed.
Client module + config + codegraph telemetry subcommand + MCP clientInfo plumbing.
Installer toggle + first-run notice. CHANGELOG entry under [Unreleased] announcing telemetry, the default, and every off-switch. Release.

Tests (no DB mocking, per repo convention; fetch mocked at globalThis.fetch): consent precedence (env > config > default), off ⇒ zero fetch calls, rollup aggregation across days, buffer cap + corrupt-buffer recovery, no-stdout invariant under MCP transport, flush abort honors timeout, installer toggle persists + re-run doesn't re-ask (__tests__/installer-targets.test.ts per house rules).

Open questions

Exact installer copy / notice wording — maintainer call before release.
uninstall event: keep or drop? (Honest churn signal vs. "pinging on the way out" optics.)
CI events are kept (tagged ci: true) because engine-in-CI is a real usage mode — revisit if it ever dominates volume.

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