Document command routing and artifact ownership

[developzoneio]

What

Routing (which command fans out to which agents) and artifact ownership (which phase/agent produces each .specs/<ID>/ file) were implicit across the command files — no consolidated view existed. This adds two reference sections to docs/architecture.md, no rewrites of existing content:

1. Command -> agent routing (after the Agents section) — a per-command tree of the subagent fan-out, including the three file-ops commands (/sd:spec, /sd:setup, /sd:release) that invoke no subagent.
2. Artifact ownership (within "Spec artifacts as durable memory") — a table mapping each spec file to its producing phase/agent and downstream readers, plus a note on the intentionally-empty cross-phase fields.

Scope

• docs/architecture.md — additive only.
• CHANGELOG.md — one ### Changed line under [Unreleased].

Item 4d of the command/agent discipline refinements backlog. Routing claims verified against the command files (feature.md, bug.md, refactor.md, perf.md, rca.md, explore.md, review.md).

Verification

bash scripts/validate.sh — all 6 checks pass.

🤖 Generated with Claude Code