docs: add HUD status control contract (#1821)

docs/architecture/hud-status-session-control.md

@@ -0,0 +1,80 @@
+# HUD Status And Session Control Contract
+
+This contract defines the portable status payload ECC uses for local operator
+surfaces, handoffs, and future HUDs. It is intentionally harness-neutral: a
+Claude Code statusline, Codex pane, dmux session, OpenCode run, or terminal-only
+workflow can emit partial data without changing field names.
+
+The canonical example lives at
+[`examples/hud-status-contract.json`](../../examples/hud-status-contract.json).
+
+## Payload Shape
+
+Every status payload uses `schema_version: "ecc.hud-status.v1"` and keeps these
+top-level sections stable:
+
+| Field | Purpose | Primary Source |
+|---|---|---|
+| `context` | Model, harness, repo, branch, worktree, session id, and context-window pressure | statusline stdin, git, session adapters |
+| `toolCalls` | Recent tool counts, pending calls, stale calls, and last tool event | `loop-status`, `tool-usage.jsonl`, hook bridge |
+| `activeAgents` | Current workers/subagents, runtime state, branch, worktree, objective, and handoff paths | dmux/orchestration snapshots |
+| `todos` | Current in-progress task and todo counts | Claude todos, local task files, plan metadata |
+| `checks` | Local and remote validation status with command/check URLs when available | CI, local commands, release gates |
+| `cost` | Session spend, token counts, budget, and trend | cost tracker, metrics bridge |
+| `risk` | Attention state, conflict pressure, stale calls, dirty worktree, and manual-review flags | readiness gates, git, queue state |
+| `queueState` | GitHub PR/issue/discussion counts, conflict queue, merge queue, and stale-salvage queue | GitHub sync, work items |
+| `sessionControls` | Supported operator actions for the current target | ECC CLI, dmux, git/GitHub |
+| `sync` | Linear, GitHub, and handoff publication state | status updates, work items, handoff writer |
+
+Fields can be `null`, empty arrays, or `"unknown"` when a harness cannot expose
+the signal. Producers should not invent incompatible names. Consumers should
+render missing sections as unavailable, not as green.
+
+## Session Controls
+
+The minimum session-control vocabulary is:
+
+| Control | Meaning |
+|---|---|
+| `create` | Start a new isolated run, worktree, or orchestration plan |
+| `resume` | Reattach to an existing session or historical target |
+| `status` | Emit the current payload without mutating state |
+| `stop` | Request a graceful stop or mark the session completed |
+| `diff` | Show current working-tree or worker diff |
+| `pr` | Open or inspect the linked pull request |
+| `mergeQueue` | Show merge-ready, blocked, and waiting-check items |
+| `conflictQueue` | Show dirty/conflicting PRs or worktrees needing integration |
+
+`sessionControls.supported` lists the controls available for the current
+harness. `sessionControls.blocked` explains unavailable controls, for example a
+missing GitHub token, no tmux session, or a read-only adapter.
+
+## Sync Contract
+
+The sync section separates durable trackers:
+
+- `Linear` records project status update id, health, and whether issue creation
+  is blocked by workspace capacity.
+- `GitHub` records the current repo, PR/issue/discussion queue counts, and the
+  latest merged or open PR tied to the session.
+- `handoff` records the durable Markdown handoff path and whether it has been
+  written after the latest batch.
+
+This makes real-time progress tracking explicit without requiring every run to
+create Linear issues or GitHub comments. When Linear issue capacity is blocked,
+the status payload can still prove progress through project updates and repo
+handoffs.
+
+## Current Implementations
+
+- `ecc status --json` exposes readiness, active sessions, skill runs, install
+  health, governance, and linked work items from the SQLite state store.
+- `ecc loop-status --json --write-dir <dir>` writes live transcript snapshots
+  and attention signals for long-running loops.
+- `ecc session-inspect <target> --write <path>` emits canonical session
+  snapshots from dmux and Claude-history adapters.
+- `scripts/hooks/ecc-statusline.js` renders compact model, task, cost, tool,
+  file, duration, directory, and context pressure signals inside Claude Code.
+
+The `ecc.hud-status.v1` payload is the common outer contract these surfaces can
+project into before ECC grows a dedicated full-screen HUD.

docs/architecture/observability-readiness.md

@@ -19,6 +19,10 @@ operator needs.
 
 - Live status: `scripts/loop-status.js` can emit JSON, watch active loops, and
   write snapshots for dashboards or handoffs.
+- HUD/status contract: `docs/architecture/hud-status-session-control.md` and
+  `examples/hud-status-contract.json` define the portable payload for context,
+  tool calls, active agents, todos, checks, cost, risk, queues, session
+  controls, and tracker sync.
 - Session traces: `scripts/session-inspect.js` can inspect Claude, dmux, and
   adapter-backed sessions, then write canonical snapshots.
 - Harness baseline: `scripts/harness-audit.js` provides a repeatable scorecard
@@ -56,9 +60,11 @@ later, but only after the local event model is useful enough to trust.
    scorecard.
 3. Run `node scripts/loop-status.js --json --write-dir .ecc/loop-status`
    during longer autonomous batches.
-4. Run `node scripts/session-inspect.js --list-adapters` to confirm which
+4. Review `examples/hud-status-contract.json` before wiring a new HUD or
+   operator dashboard.
+5. Run `node scripts/session-inspect.js --list-adapters` to confirm which
    session surfaces are available.
-5. Use ECC2 tool logs for risky operations, conflict analysis, and handoff
+6. Use ECC2 tool logs for risky operations, conflict analysis, and handoff
    review before increasing autonomy.
 
 The end-state is practical: before asking ECC to run larger multi-agent loops,