0aee2c0981
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
3.6 KiB
Desired, Derived, and Observed Fleet State
One writable authority
The canonical local v2 roster at <MOSAIC_HOME>/fleet/roster.yaml is desired state. Membership, stable identity, class, runtime/provider/model selection, launch policy, enablement, and persisted running/stopped intent are written only through generation-guarded roster mutations.
Derived projections are reproducible consequences of that authority:
<name>.env.generated;- exact roster-named tmux sessions on the configured socket after reconciliation;
- systemd service targets managed by installation/reconciliation.
Current systemd unit enablement is not yet lifecycle-conformant at boot: installation can enable every
agent unit, and the launcher projection does not carry enabled or desired_state. Therefore reboot
preservation for stopped/disabled agents remains an FCM-M3-002 acceptance hold, not a guaranteed
projection behavior.
Observed evidence available to current roster-v2 status commands includes systemd active state, tmux
presence, holder ownership, and unmanaged sessions. Heartbeat files are observational in the wider fleet,
but roster-v2 status, doctor, and verify do not currently read them. Observation never writes back
to the roster.
Generation and ownership
generation is a positive integer concurrency fence. A mutating request must provide the current value. Successful changed CRUD increments it exactly once; stale or concurrent writers fail before mutation. Apply/reconcile rereads the canonical roster under a private exclusive lock and uses only that generation and content for effects.
Ownership is exact, never fuzzy. Reconciliation is limited to roster names, the configured socket, the exact holder session, a private installation identity, and private managed paths. An ownership mismatch, unmanaged session, unsafe path, stale generation, or ambiguous lock fails closed.
Drift decisions
| Observation | Interpretation | Safe response |
|---|---|---|
| Generated file differs or is missing | Derived projection drift | Review apply --dry-run; regenerate from the roster. |
Desired running, exact session missing |
missing-session |
Diagnose ownership/runtime, then reconcile if safe. |
Desired stopped, exact session present |
unexpected-session |
Inspect; reconciliation may stop only the proven roster target. |
| Disabled agent running | disabled-running |
Inspect; disabled state wins during explicit safe reconciliation. |
| Unknown session on the configured socket | Unmanaged state | Report only. Do not adopt, rename, or kill it. |
| Heartbeat stale in the wider fleet | Liveness evidence | Diagnose separately; current roster-v2 status does not read heartbeat. |
status and doctor classify. verify is also observational but exits non-zero when ownership, drift, or unmanaged-state checks fail. plan/apply --dry-run validates proposed projection and lifecycle work without mutation. apply and reconcile converge only after all preconditions pass.
A partial projection failure does not roll the roster back. Treat the committed roster as authority and regenerate. A lifecycle failure after projection completion preserves both roster and projections for inspection. Sensitive legacy values are never printed; diagnostics are bounded to stable codes, key names where applicable, and hashes.