feat: scaffold redsen-lean-harness v0.1.0

Recovered from crashed session (Node OOM). Repo contains full P0-P6 scaffold: plugin.json/marketplace.json, AGENTS.md, ADRs 0001-0006, lh CLI (init/index/graph/lane/run/memory/host/report/doctor), 10 .github/agents, 12 CLI skills, instructions, context7 mcp.json, and unit/e2e test suite. Fixed: run.mjs read --in-tokens/--out-tokens but tests and CLI docs use --input-tokens/--output-tokens, so telemetry totals were always 0. Now accepts both forms. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-09-09 22:44:15 +02:00
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+# ADR 0001 — Markdown owns behaviour, Node owns determinism
+
+- **Status**: Accepted
+- **Date**: 2026-09-09
+
+## Context
+
+The harness must be *simple*, *lean on context*, *distributable as a plugin*, and run on two
+hosts (GitHub Copilot CLI, VS Code Copilot) that both already contain a capable agent runtime.
+
+There is a strong temptation to build an orchestrator process that drives the model directly.
+That path produces a second agent runtime we would have to maintain, and it cannot be shipped
+as a plugin because plugins run *inside* the host.
+
+## Decision
+
+Split the system in three, with a hard boundary:
+
+| Layer | Owns | Artifact |
+| --- | --- | --- |
+| Markdown | Behaviour — agents, skills, instructions | `.github/` |
+| Node CLI (`lh`) | Determinism — index, gates, lanes, telemetry, memory | `src/` |
+| Host | Execution — subagents, fleet, tools, models | Copilot CLI / VS Code |
+
+`lh` never calls a model. Agents never do arithmetic, parsing, git plumbing, or bookkeeping
+by hand. **We do not reimplement an agent runtime.**
+
+## Consequences
+
+- The same `.github/` tree works in both hosts; only the scheduler differs (see ADR 0003).
+- `lh` is trivially testable — it is pure I/O with no model in the loop.
+- Anything the host cannot do, we cannot do. Accepted: host capability detection (`lh host`)
+  makes the limitation explicit and degrades rather than failing.
+- Behaviour changes are markdown diffs, reviewable in a PR without running anything.
+
+## Alternatives considered
+
+- **Standalone orchestrator binary** — rejected: not plugin-distributable, duplicates the host.
+- **Everything in markdown, no CLI** — rejected: indexing, worktrees, structural analysis and
+  token accounting are not things an LLM should do by hand; they are slow, expensive and unreliable.
+- **Everything in Node, markdown as prompts only** — rejected: opaque, unreviewable, and it
+  breaks the self-documenting requirement.