Prefix CUST-ADR-001–011 and record owner, revision, and review dates so policy-nexus can publish them. Estate arc42 chapter 9 updated.
126 lines
4.8 KiB
Markdown
126 lines
4.8 KiB
Markdown
---
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id: CUST-ADR-002
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type: architecture-decision-record
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title: "Custodian Agent Runtime — v0.1 Bootstrap Design"
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status: accepted
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owner: the-custodian
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revision: "accepted-1"
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last_reviewed: "2026-03-12"
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review_interval: 6m
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decided_by: Bernd Worsch
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date: "2026-03-12"
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tags: ["architecture", "agent-runtime", "llm", "ooda", "bounded-agency"]
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---
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# ADR-002: Custodian Agent Runtime — v0.1 Bootstrap Design
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## Status
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Accepted.
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## Context
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CUST-WP-0001 requires a first working skeleton of the Custodian as an acting
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agent: a loop that observes project state, reasons about it, and executes
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bounded write operations — without human interaction for each step.
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The dependencies (llm-connect, operational Railiance infra) are now resolved.
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This ADR captures the five key architectural decisions for the v0.1 bootstrap.
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## Decisions
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### D1 — Location: `runtime/` inside the-custodian (not a new repo)
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**Decision:** The runtime lives under `the-custodian/runtime/` as a standalone
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Python package (`pyproject.toml`, own venv) rather than a new repository.
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**Rationale:** The runtime is tightly coupled to canon (reads constitution,
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memory) and the state-hub (its primary coordination layer). A separate repo
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adds friction with no v0.1 benefit. The existing `runtime/` scaffold confirms
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the original intent. Extraction to its own repo is deferred to when the
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runtime has stable boundaries and multiple consumers.
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### D2 — OODA loop: single-pass synchronous CLI
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**Decision:** One `run()` call = one complete Observe → Orient → Decide → Act
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cycle. Entry point is a CLI (`agent.py`) invoked manually or by a cron job.
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```
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Observe — HTTP GET to state-hub: state summary or domain summary
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Orient — Load constitution + build structured LLM context prompt
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Decide — Single LLM call (via llm-connect) returns a JSON action plan
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Act — Execute only sanctioned write operations from the plan
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```
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**Rationale:** Async event loops and daemons add operational complexity that
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v0.1 doesn't need. A single-pass CLI is testable, debuggable, and can be
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scheduled externally. The transition to an event-driven loop is Phase 2.
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### D3 — LLM backend: ClaudeCodeAdapter by default
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**Decision:** The runtime uses `llm_connect.ClaudeCodeAdapter` as its default
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LLM backend (shells out to `claude --print`). Provider is configurable via
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`--llm` flag to support `gemini`, `openrouter`, or `openai`.
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**Rationale:** `ClaudeCodeAdapter` requires no API key and honours the
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Local-First value (V2). All current deployments have Claude Code available.
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The llm-connect abstraction means switching providers is a one-line change.
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### D4 — Action constraint: three sanctioned write operations only
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**Decision:** The agent may execute exactly three state-hub write operations
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without human approval:
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1. `add_progress_event` — append an observation to the event log
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2. `update_task_status` — mark a task done/in_progress (reversible)
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3. `flag_for_human` — raise an intervention flag (escalation, not action)
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All other operations (create workstream, record decision, resolve decision,
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write to canon) require human approval before execution.
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**Rationale:** Constitution §3/§4 require bounded agency. The three operations
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are either append-only (progress events), reversible (task status), or
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explicitly escalating (flag). They cannot produce irreversible harm.
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### D5 — LLM response format: JSON block in markdown
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**Decision:** The LLM is prompted to return a Markdown response with a
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fenced ```json block containing the structured action plan:
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```json
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{
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"observations": ["..."],
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"progress_events": [
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{"summary": "...", "workstream_id": "...", "event_type": "note"}
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],
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"tasks_to_update": [
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{"task_id": "...", "status": "done"}
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],
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"tasks_to_flag": [
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{"task_id": "...", "note": "..."}
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]
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}
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```
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The surrounding Markdown is preserved as a human-readable reasoning trace
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and written to `memory/working/` as a session note.
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**Rationale:** JSON blocks are robust to extraction (delimited), LLMs produce
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them reliably with clear instructions, and the surrounding prose gives Bernd
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an auditable reasoning trace without requiring a separate reasoning step.
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## Consequences
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- `runtime/` becomes a standalone Python package; `make agent-run DOMAIN=x`
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invokes it.
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- The runtime has no DB schema changes and no new API endpoints — it is a
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pure client of the existing state-hub HTTP API.
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- Autonomous actions are limited to append-only writes and escalations. Any
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expansion of the action surface requires a new ADR and human approval.
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- The v0.1 loop is single-user (Bernd). Multi-agent expansion is Phase 2+.
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## Deferred
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- Async event loop / daemon mode (Phase 2)
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- RAG over canon (Phase 1 roadmap item)
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- Tool adapters beyond state-hub HTTP (planned in `runtime/tool_adapters/`)
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- Deployment on Railiance k3s as a scheduled CronJob
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