refactor(agent-identity): unified prompt base for voice + phone + core (kill persona drift)

Start by comparing src/voice-agent-config.ts, skills/phone-conversation/scripts/phone-agent-config.ts, and src/voice-context.ts, then review the voice-10 and phone-3 behavior-anchor snapshots. Extract only invariant identity facts and the duplicated stand/repository lines; keep interaction styles and tools local. Done means the anchors still pass except for the intentional local-run correction.

Problem

Sutando's agent identity is stated in three independent prompts that drift:

• src/voice-agent-config.ts — "you are Sutando, belongs entirely to the user…"
• skills/phone-conversation/scripts/phone-agent-config.ts — "you are Sutando, a personal AI assistant…" (per call-variant → several near-duplicate copies)
• src/voice-context.ts — "Sutando's task execution engine…" (the work-tool core)

Because each states identity separately, a fact like "runs locally on the user's Mac, not cloud" is absent from all of them, and any correction has to be pasted into each place. (Triggering symptom: #2011 — the phone agent fabricated "cloud-based" when asked where it runs.)

Proposal — unified prompt base

Extract one agent-identity module holding the invariant facts — name · belongs to the user · runs locally on the user's Mac · Stand identity · repo URL · core capabilities — imported by voice + phone + core. State identity once; fix "where do I run" everywhere at once; kill the whole drift class.

Boundary (load-bearing)

Shared base = identity & facts. Per-surface stays local = interaction style & tools: phone's "1–2 sentences / hang_up semantics / IVR", voice's mode-switch + meeting note-taking. Over-unifying past that couples the surfaces and loses per-surface tuning — so the base is the identity core, not the whole prompt.

Discipline

Natural sequel to step 5 (which unified the runtime plumbing; this unifies the persona). Behavior-preserving extraction, anchor-gated — the voice-10 / phone-3 behavior-anchor snapshots are the golden net; the "cloud-based" correction folds in as the single intentional delta. Also folds the currently-duplicated standIdentityLine/standIdLine + repoUrlLine helpers into the shared module.

Relation

Subsumes #2011 (persona accuracy fix). Deferred — parked for a later focused pass per owner (2026-07-07).