ADR-0030: Retain OSC progress as PTY-local detection evidence

Status: proposed, 2026-10-11. Spec: specs/045-osc-progress-grok/.

Context

Grok emits OSC 9;4 busy/idle signals used by herdr's declarative manifest. Treating these as ordinary OSC 9 messages creates notifications containing protocol text. Mapping progress directly to lifecycle would bypass program scoping, visible blocker priorities, user overrides and semantic hook authority.

Decision

The scanner emits Progress separately from Notify and retains the validated payload after 9;. States are 0..4, with optional/empty percentage or -1..100. The -1 sentinel supports Grok. Evidence is at most 32 ASCII bytes; malformed reserved progress is ignored. Ordinary OSC 9 text and bare BEL are unchanged.

Each PTY owns its scanner. The classifier and explain read the current handle's progress through an explicit matcher input and osc_progress region. Missing progress never matches. Exit/close drop the handle and respawn creates a fresh scanner, so evidence cannot survive a cold restart or PTY replacement. Progress does not add persisted state or per-update events.

Bundle Grok under generic binaries = ["grok", "grok-build"]. Port herdr 2563803's priorities, including visible blockers over busy progress and visible work over stale idle titles. Reuse existing known-agent idle fallback, launcher discovery, user replacement rules and Store lifecycle transitions.

Consequences

Other agents can use this region in future manifests. This PR adds Grok only. No native Grok hooks or resume installer is implied. Progress is best-effort retained terminal evidence, not a completion authority. Programs started within an existing shell use the existing process refresh/scoping behavior. They share retained OSC evidence until overwritten. Foreground-generation reset within one PTY requires a separate process-identity change and is outside this PR.

Sources: herdr Grok manifest, ConEmu OSC reference.