operator: ambient loop tick carries a live fleet snapshot

[edwin-zvs]

Problem

The operator ambient loop (#352) fires every ~5 min but produced no useful observations. The tick injected a content-free prompt:

OBSERVATION: ambient operator loop tick. Quietly inspect only if useful; … reply exactly noted if nothing needs surfacing.

With no fleet data and a strong silence bias in the system prompt, the Operator had nothing concrete to react to and defaulted to noted essentially every tick. Confirmed against the live operator — when asked "Any other observations?", it replied:

"No — only the repeated ambient operator loop tick observations. No errors, approvals, done events, or fleet alerts surfaced."

(The data-carrying fleet-event observations only fire on sparse state transitions; between them the ambient loop carried zero signal.)

Fix

Each ambient tick now pulls the daemon session list and injects a compact fleet snapshot instead of a blank prompt:

• counts of active sessions by state (running / awaiting_input / errored),
• changes since the last tick (sessions that went errored / awaiting_input / done — a per-tick delta),
• what needs attention now (errored, or awaiting_input ≥ 30m),
• and a nudge to inspect a stuck/errored/surprising session or reply noted.

The Operator's own session is excluded. If the daemon can't be reached, it falls back to the original bare prompt. Delta state is in-memory (resets on adapter restart → first tick emits a baseline with no delta). Lists are capped to stay low-noise. The loop interval, orchestrator-only gate, and fleet-event pipeline are unchanged.

Verification

• Pure formatter (format_ambient_observation) is unit-tested: counts exclude self, and a running→errored transition surfaces as a delta with updated counts.
• Built clean; 34 interactive tests pass.
• Rendered live against the running fleet:

  OBSERVATION: ambient operator loop tick.
  Fleet now: 5 running, 2 awaiting_input, 0 errored.
  Changes since last tick: (first tick — baseline only).
  Needs attention: none.
  If a session looks stuck, errored, or surprising, inspect it …
  

Spec: specs/0021-operator-ambient-tick-carries-fleet-snapshot.md. Code is in agentd-adapter-zarvis.