Files
stack/docs/fleet/concepts/desired-vs-observed-state.md
T
veronica f0d2dd9920 docs(W4): stamp kind and status front matter on 104 live documents
Applies the document contract from
docs/plans/2026-08-20_stack-docs-flatten-and-alignment.md section 3, partially:
`kind` and `status` only. `parent` is deliberately held until the flatten in
section 4 lands, so that 127 documents do not have to be re-pointed by hand
when docs/fleet/NORTH_STAR.yaml moves to docs/NORTH_STAR.yaml.

Scope, measured on origin/next at 63069149:

  127 live docs   = all *.md under docs/ minus docs/archive/ minus docs/_old_structure/
  104 stamped     here
   19 held        operator judgement (plan section 9), worklist in the same PR
    3 held        the SUPERSEDED TASKS.md stamps, which cite the moving path
    1 untouched   docs/fleet/FLEET-DOCTRINE.md, already stamped in W1

Kinds applied: 54 guide, 34 record, 9 spec, 6 tracking, 1 projection.
Every row carries a confidence and a one-line rationale in the worklist.

Two collisions with the existing state, both flagged rather than resolved:

1. docs/README.md:150-160 already documents a front-matter convention
   (title/type/audience/status/source_of_truth) with its own allowed values.
   It is applied to 4 of 127 files. Its `status` vocabulary is
   current|draft|deprecated|historical; the new contract's is active|superseded-by.
   The key collides. This commit lets the new contract win and rewrites
   `status: current` to `status: active` on those 4 files, keeping their other
   legacy keys untouched. No code reads any of them: `git grep source_of_truth`
   outside docs/ returns nothing. docs/README.md still prescribes the old
   convention and is an operator row, so it is not edited here.

2. Two of the plan's 20 operator rows are YAML files, not markdown
   (docs/fleet/examples/roster-v2.yaml, docs/openapi-tess.yaml), and the
   contract's front-matter form has no defined meaning for a .yaml document.
   That gap also applies to docs/fleet/NORTH_STAR.yaml, the source of truth
   itself. Raised in the worklist.

A third row from the plan, docs/fleet/north-star.md, no longer exists: W1
renamed it to docs/fleet/FLEET-DOCTRINE.md.

Verification: 104/104 parse with the expected kind and status in front matter;
the check was shown to reject a wrong kind before it was trusted. The diff
removes 4 lines total, all of them `status: current`.
2026-08-20 19:30:25 -05:00

48 lines
3.7 KiB
Markdown

---
kind: guide
status: active
---
# 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.