tend/README.md

# Gamertan Tend

Tend is an opinionated release and deployment tool for small Go services on
Linux, systemd, and Caddy. It packages a clean pushed commit, records exact
build provenance, activates a health-checked candidate, and keeps rollback
state explicit.

The v0.2 development line supports two quiet deployment shapes:

- Caddy-switched blue/green services.
- A singleton service with an isolated transient candidate check.

It does not manage databases, migrations, containers, Kubernetes, or arbitrary
shell hooks. Application-specific data activation remains application-specific.

## Commands

```text
tend check    --config tend.json
tend package  --config tend.json --version v0.2.0-preview.2 --out dist
tend inspect  --config tend.json --artifact FILE --sha256 HEX --approve-sha256 HEX
tend push     --target tend-deploy@host --known-hosts FILE --service NAME --artifact FILE --sha256 HEX --approve-sha256 HEX
tend receive  --policy /etc/tend/receive-policy.json
tend check-server --policy /etc/tend/receive-policy.json
tend deploy   --config /etc/tend/services/example-site.json --artifact FILE --sha256 HEX --approve-sha256 HEX
tend status   --config /etc/tend/services/example-site.json
tend reconcile --config /etc/tend/services/example-site.json --json
tend rollback --config /etc/tend/services/example-site.json
tend prune    --config /etc/tend/services/example-site.json --keep 3 [--apply]
```

`inspect` performs the complete archive, checksum, approval, manifest, SBOM,
and binary-identity validation without staging or activating a release.
`reconcile` is also read-only: it compares Tend's journal with conventional
release symlinks, systemd units, the installed release identity, and the Caddy
handler. It reports drift and retained-candidate residue without silently
"repairing" a service.

`push` transfers one approved artifact through a pinned OpenSSH connection. A
forced, no-shell receiver maps the service name to one root-owned configuration;
it accepts no remote path, environment value, URL, or shell fragment. Production
hosts receive binaries and evidence, never source or Go dependencies.

Schema 2 keeps all services under `/etc/tend/services/`, references a distinct
root-owned `0600` environment file for each service, and serializes activation
through `/run/lock/tend-deploy.lock`. Builds and transfers remain parallel;
only the short Caddy/service activation phase is host-wide. Tend is still a
single command, not a daemon.

Each service also keeps a bounded JSONL deployment-event stream and explicit
desired, candidate, active, previous, and last-attempt release identities. The
stream contains only fixed provenance and lifecycle fields; Observatory may
ingest it later, but an event-write failure never blocks deployment or rollback.
After Caddy reload, Tend repeatedly probes the configured canonical HTTPS
origins for the activation window. Blue/green deployments simultaneously keep
checking the previous slot, restoring the prior handler and inactive-slot state
if routed traffic or continuity fails.

Singleton activation and rollback candidates use an operation-scoped systemd
unit and persist a bounded lease containing the operation, release, unit,
address, and start time in a separate adjacent file. Conventional deployment
state remains schema 1 so a retained older binary can still read active and
previous release identities; operators must reconcile before downgrading while
a lease exists. `tend
reconcile --json` compares that lease with unit activity, release pointers, and
the exact Caddy handler file without changing any of them. It deliberately does
not stop or clear a retained candidate: that process may still be the only
healthy route after an interrupted recovery.

Dry-run and digest approval are intentional friction. See the
[schema-2 migration guide](docs/SCHEMA_V2_MIGRATION.md) and the
[two-service walkthrough](docs/WALKTHROUGH.md).

Run `./scripts/verify.sh` on Linux. That required release lane exercises tests,
the race detector, vet, deterministic builds, schema-2 examples, and the
dependency-free module graph. Tend supports Linux hosts with systemd and Caddy;
WSL may be used as a Linux development environment, but native Windows is not a
supported execution, deployment, or release-gate platform.

The v0.1 public preview and immutable `v0.2.0-preview.1` each completed
maintenance releases and explicit rollback/reactivation for both Gamertan and
the Sandwich Hime website using one reviewed candidate. See the dated
[dogfood evidence](docs/DOGFOOD_EVIDENCE.md) for exact scope and limitations.

The additive `v0.2.0-preview.2` candidate keeps that transport and activation
contract while adding bounded deployment-event JSONL, routed-origin continuity,
rollback annotations, and the operational findings recorded through real
dogfooding. Preview 1 remains unchanged. Preview 2 will not be tagged until one
identical binary has deployed, rolled back, and reactivated Gamertan, the
Sandwich Hime website, and Gamertan Observatory.
Operational friction discovered while applying the same contract to new
services is tracked separately in the
[dogfood friction ledger](docs/DOGFOOD_FRICTION.md). The ledger preserves the
fail-closed behavior and records candidate product improvements instead of
normalizing application-specific deployment workarounds.
The canonical public repository begins with a sanitized root snapshot rather
than the private development history.

## Licensing

Tend and its release machinery are AGPL-3.0-only. Reusable example
configuration and service templates under `examples/` are 0BSD.