docs: write README, docker-compose example, env example

self-hosted/.env.example

@@ -0,0 +1,3 @@
+# Required
+ROUTINE_FIRE_URL=https://api.anthropic.com/v1/claude_code/routines/trig_xxx/fire
+ROUTINE_FIRE_TOKEN=sk-ant-oat01-xxxxxxxx

self-hosted/README.md

@@ -1 +1,130 @@
 # claude-code-routine-cron
+
+Self-hosted Go daemon that fires a [Claude Code routine](https://code.claude.com/docs/en/routines) on a precise cron schedule via the [`/fire` API](https://platform.claude.com/docs/en/api/claude-code/routines-fire). Packaged as a multi-arch Docker image on GHCR.
+
+> [!TIP]
+> **Anthropic's routine editor now ships a built-in cron trigger** — that runs on Anthropic's infra, no setup. Use it first.
+>
+> This repo is for users who explicitly want **self-hosted scheduling**: precise timing (no GitHub Actions delays), behind-firewall, on-prem audit trail, or to integrate with their own infra.
+
+## Why this vs `claude-code-routine-trigger`
+
+|                  | [claude-code-routine-trigger](https://github.com/tiennm99/claude-code-routine-trigger) | **claude-code-routine-cron** (this repo) |
+| ---------------- | -------------------------------------------------------------------------------------- | ---------------------------------------- |
+| Runs on          | GitHub Actions runners                                                                 | your infra (Docker host, k8s, NAS, RPi)  |
+| Cost             | free (within GitHub minutes)                                                           | minimal (your infra)                     |
+| Cron precision   | ±30 min – 2 h, can drop runs                                                           | sub-second                               |
+| Setup            | fork + 2 repo secrets                                                                  | 2 env vars + cron + Docker               |
+| Secret storage   | GitHub repo secrets                                                                    | host env / Docker secrets / k8s Secret   |
+| Audit trail      | GitHub Actions runs page                                                               | container stdout                         |
+
+## Quickstart
+
+```bash
+docker run -d --name claude-routine \
+  --restart unless-stopped \
+  -e ROUTINE_FIRE_URL='https://api.anthropic.com/v1/claude_code/routines/trig_.../fire' \
+  -e ROUTINE_FIRE_TOKEN='sk-ant-oat01-...' \
+  -e CRON_SCHEDULE='0 9 * * *;0 18 * * *' \
+  -e TZ='Asia/Ho_Chi_Minh' \
+  ghcr.io/tiennm99/claude-code-routine-cron:latest
+```
+
+Tail logs:
+
+```bash
+docker logs -f claude-routine
+```
+
+A successful fire logs a JSON line with `claude_code_session_url`. Open it to watch the run.
+
+## Environment variables
+
+| Name                 | Required | Default                                  | Notes |
+| -------------------- | :------: | ---------------------------------------- | ----- |
+| `ROUTINE_FIRE_URL`   | yes      | —                                        | Anthropic `/fire` endpoint. From routine editor → API trigger. |
+| `ROUTINE_FIRE_TOKEN` | yes      | —                                        | `sk-ant-oat01-...` per-routine token. Shown once in the editor. |
+| `CRON_SCHEDULE`      | yes      | —                                        | One or more standard 5-field cron expressions. Split on `;` or newlines. |
+| `TZ`                 | no       | `UTC`                                    | IANA tz name (`Asia/Ho_Chi_Minh`, `America/New_York`, …). Cron evaluates in this zone. |
+| `TEXT_TEMPLATE`      | no       | `Scheduled trigger at {{.LocalTime}}`    | Go [text/template](https://pkg.go.dev/text/template); see *Templates*. |
+| `LOG_LEVEL`          | no       | `info`                                   | `debug`, `info`, `warn`, `error`. |
+
+Validation is fail-fast: missing required vars or malformed crons/timezones/templates cause the daemon to exit with a clear error before any HTTP traffic.
+
+## Multiple schedules
+
+Use `;` (or newlines, in YAML block scalars) to register multiple crons:
+
+```yaml
+environment:
+  CRON_SCHEDULE: |
+    0 9 * * *
+    0 13 * * *
+    0 18 * * *
+```
+
+Each schedule fires independently; all use the same `TEXT_TEMPLATE`, URL, and token.
+
+## Templates
+
+The `TEXT_TEMPLATE` env var is rendered as a Go `text/template` per fire with these variables:
+
+| Var          | Type        | Example                          |
+| ------------ | ----------- | -------------------------------- |
+| `.Now`       | `time.Time` | UTC time of the fire             |
+| `.LocalTime` | `string`    | `2026-05-08 23:30 +07`           |
+| `.Cron`      | `string`    | `0 9 * * *` — the expression that fired |
+
+Example:
+
+```bash
+-e TEXT_TEMPLATE='Daily digest at {{.LocalTime}} (cron {{.Cron}})'
+```
+
+## docker-compose
+
+See [`docker-compose.example.yml`](./docker-compose.example.yml) and [`.env.example`](./.env.example):
+
+```bash
+cp docker-compose.example.yml docker-compose.yml
+cp .env.example .env       # then edit secrets
+docker compose up -d
+```
+
+## Security
+
+- The token is **per-routine**: a leak only fires that one routine.
+- Token never appears in logs (verified by tests).
+- No retry on failure — each `/fire` POST creates a new session, retries would multiply sessions and burn quota.
+- Image is `gcr.io/distroless/static-debian12:nonroot` — no shell, no package manager, runs as UID 65532.
+- TLS to `api.anthropic.com` uses standard Go cert verification.
+
+## Beta header
+
+The request pins `anthropic-beta: experimental-cc-routine-2026-04-01`. When Anthropic ships a new dated beta, bump it via a new release. Older dated values keep working for a transition window per Anthropic's beta policy.
+
+## Operational notes
+
+- **Time accuracy**: cron correctness depends on the host clock. Run NTP / sync on the Docker host.
+- **Restart policy**: use `--restart unless-stopped` (or k8s `Deployment`) — the daemon does not self-restart on panic.
+- **Pin tags in production**: prefer `:vX.Y.Z` over `:latest`.
+- **No idempotency**: avoid retry loops in upstream automation that POSTs the same alert twice.
+
+## Build from source
+
+```bash
+git clone https://github.com/tiennm99/claude-code-routine-cron
+cd claude-code-routine-cron
+go build .
+./claude-code-routine-cron     # uses env vars from your shell
+```
+
+Tests:
+
+```bash
+go test -race -cover ./...
+```
+
+## License
+
+[Apache-2.0](./LICENSE)

self-hosted/docker-compose.example.yml

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+services:
+  claude-routine:
+    image: ghcr.io/tiennm99/claude-code-routine-cron:latest
+    restart: unless-stopped
+    environment:
+      ROUTINE_FIRE_URL: ${ROUTINE_FIRE_URL}
+      ROUTINE_FIRE_TOKEN: ${ROUTINE_FIRE_TOKEN}
+      CRON_SCHEDULE: |
+        0 9 * * *
+        0 18 * * *
+      TZ: Asia/Ho_Chi_Minh
+      LOG_LEVEL: info
+      # Optional: override the default text sent to the routine.
+      # TEXT_TEMPLATE: "Daily digest at {{.LocalTime}} (cron {{.Cron}})"