docs: telemetry guide (disable with DO_NOT_TRACK=1) (#232)

* fix: TelemetryCallback __bases__ crash + 12 TRL integration tests

The dynamic __bases__ assignment to inject TrainerCallback as a base
class fails in Python: "deallocator differs from object". Fixed by
creating a proper subclass at definition time instead.

12 new tests:
- Mock rollout_func: correct keys, count, reward variance
- Config separation: TrainingConfig has no TRL fields, wrapper accepts trl_config
- Wrapper construction: all callback combinations, trl_config passthrough
- TelemetryCallback: importable, fires events

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: telemetry guide — how to disable globally with one line

DO_NOT_TRACK=1 in .env disables all telemetry. Already supported,
just needed documentation. Covers what we collect, what we don't,
privacy scrubbing, CI behavior, and source code links.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: abrichr

docs/TELEMETRY.md

@@ -0,0 +1,82 @@
+# Telemetry
+
+OpenAdapt collects anonymous usage telemetry to understand how the tools are used and prioritize development. No screenshots, text content, API keys, or personally identifiable information is ever collected.
+
+## Disabling telemetry
+
+Add one line to your `.env` file:
+
+```env
+DO_NOT_TRACK=1
+```
+
+That's it. All telemetry is disabled globally — no events are sent, no background threads are started, no network connections are made.
+
+This works across all OpenAdapt packages (openadapt-evals, openadapt-ml, openadapt-capture) because they all check this variable before sending any data.
+
+### Alternative
+
+```env
+OPENADAPT_TELEMETRY_ENABLED=false
+```
+
+Both `DO_NOT_TRACK=1` and `OPENADAPT_TELEMETRY_ENABLED=false` have the same effect. `DO_NOT_TRACK` follows the [Console Do Not Track](https://consoledonottrack.com/) standard used by Homebrew, Gatsby, Next.js, and other OSS projects.
+
+### Environment variable (no .env file)
+
+```bash
+export DO_NOT_TRACK=1
+```
+
+Or per-command:
+
+```bash
+DO_NOT_TRACK=1 python scripts/train_trl_grpo.py --task-dir tasks/ ...
+```
+
+## What we collect
+
+When telemetry is enabled, we collect:
+
+- **Event counts**: how many training runs, agent episodes, demos recorded
+- **Timing**: how long operations take (not wall-clock timestamps)
+- **Package metadata**: package version, Python version, OS (no hostname or IP)
+- **Training metrics**: reward mean, loss value, gradient norm (no model weights or training data)
+
+We do **not** collect:
+
+- Screenshots or images
+- Text content, prompts, or model outputs
+- API keys, passwords, or credentials
+- File paths with usernames
+- IP addresses or hostnames
+- Any data that could identify a person or organization
+
+## How it works
+
+Telemetry events are sent to [PostHog](https://posthog.com/) via a background thread. Events are batched and sent asynchronously — telemetry never blocks your training or evaluation. If the network is unavailable, events are silently dropped.
+
+The telemetry client generates a random anonymous ID stored locally at `~/.openadapt/telemetry_distinct_id`. This ID is not linked to any personal information.
+
+## Automatic scrubbing
+
+Even if telemetry is enabled, a privacy scrubber automatically removes:
+
+- Email addresses and phone numbers (pattern-matched)
+- API keys and tokens (key name detection)
+- File paths containing usernames (sanitized to `~`)
+- Any field named `password`, `token`, `secret`, `api_key`, etc.
+
+## CI environments
+
+Telemetry is automatically disabled in CI environments unless explicitly enabled:
+
+```bash
+OPENADAPT_TELEMETRY_IN_CI=true  # opt-in for CI
+```
+
+## Source code
+
+- Privacy scrubber: [openadapt-telemetry/privacy.py](https://github.com/OpenAdaptAI/openadapt-telemetry)
+- PostHog client: [openadapt-telemetry/posthog.py](https://github.com/OpenAdaptAI/openadapt-telemetry)
+- Event definitions: [openadapt-evals/telemetry.py](https://github.com/OpenAdaptAI/openadapt-evals/blob/main/openadapt_evals/telemetry.py)