Seams under test: agent::parse_manifest; OverlayAdapter as AgentAdapter; Ctx::adapter routing; procscan helpers against own pid; socket-level promotion/cwd/malformed tests; integration status output.

Phase 1: Setup

T001 Add toml = "0.8" to signaltty-agent/Cargo.toml (workspace already pins it via signaltty-plugin).

Phase 2: Foundational

T002 [US1] Manifest + parse_manifest in crates/signaltty-agent/src/manifest.rs (RED: valid/legacy-compat/bad kind/bad enum/unknown-fields-ignored; GREEN).
T003 [US1] OverlayAdapter + field-by-field fallthrough + unit tests (identify merge, lifecycle override vs builtin, session key, resume template, display override, channel passthrough).
T004 [US1] detect_kind_with_overlays + agents_dir() in paths.rs (SIGNALTTY_AGENTS_DIR override) + Config.agents_dir.
T005 [US2] procscan.rs: deepest_descendant, proc_argv0, proc_cwd, scan (change-only pane.updated) + unit tests against own pid (no fixtures that depend on machine state).

Phase 3: US1 - Manifest overlays (P1) 🎯 MVP

T006 [US1] Server startup load (isolated per-file failures, logged) + Ctx::adapter(); route hook-event/report-session/decision-answer/spawn detection through it.
T007 [US1] Integration: manifest maps sleep→codex in temp agents dir → spawn promotes at spawn; hook override hook works; malformed file doesn't block startup.
T008 [US1] integration status lists manifests (name/kind/file).

Phase 4: US2 - Live /proc refresh (P2)

T009 [US2] 10s tick in server.rs (scan → broadcast + mark_persist only when non-empty).
T010 [US2] Integration: generic sleep pane with no manifest keeps kind but gets cwd; with manifest promotes to codex with one pane.updated (subscribe + assert single event); cwd change via sh -c 'cd /tmp; sleep 30' visible within 15s.

Phase 5: Polish

T011 Docs: docs/07-agents.md manifest section + docs/adr/0009-agent-manifests.md.
T012 Gates: fmt, clippy (zero new), full tests; commits area: what.