docs(dox): build out the DOX AGENTS.md hierarchy

Root Child DOX Index assembled, plus a per-module AGENTS.md across the tree
(core/*, infrastructure/*, apps/*, testing/*, and docs/examples/frontend/etc),
each following the DOX section shape: Purpose, Ownership, Local Contracts,
Work Guidance, Verification, Child DOX Index.

docs/AGENTS.md

@@ -0,0 +1,37 @@
+# docs/ — AGENTS.md
+
+## Purpose
+
+Human-readable documentation for the CORREX project: architecture decisions, module specs, QA run plans, schemas, epics, and design references. Not source of truth for build status — source of truth is git log + live code.
+
+## Ownership
+
+Maintained alongside the features they describe. Any agent shipping a significant feature must update or create the relevant doc.
+
+## Local Contracts
+
+- `architecture/` — stable, high-level architectural docs (context layers, event model, replay model, security boundaries).
+- `decisions/` — ADRs (adr-NNNN-*.md). Append-only. Never delete or retroactively alter a decided ADR; write a superseding one instead.
+- `qa/` — QA run plans (QA-*.md). Each maps to a shipped feature. `TEMPLATE.md` is the canonical shape. `ENV.md` describes the required live environment. `README.md` explains the QA process.
+- `specs/` — feature specs by date-slug. Inputs for planned or in-flight work.
+- `schemas/` — canonical JSON schemas for structured outputs (analysis, brief_echo, design, execution_plan, impl_plan). Shared across the router and validator.
+- `epics/`, `modules/`, `diagrams/`, `design/`, `reviews/`, `visual/` — supporting reference material.
+
+**⚠️ STALE / DO NOT TRUST FOR STATUS:**
+- `docs/plans/` — gitignored. Contains old implementation plans. Never reflects current build state.
+- `docs/future/` — gitignored. Speculative, may be outdated. Verify any claim against git log + live code.
+
+## Work Guidance
+
+- QA plans live in `qa/`. Use `qa/TEMPLATE.md` as the starting shape when creating a new one.
+- ADRs go in `decisions/`. Follow the existing numbering sequence.
+- Specs go in `specs/` under a `YYYY-MM-DD-<slug>/` directory.
+- Never trust `docs/plans/` or `docs/future/` for feature status. Always verify against `git log` and live source.
+
+## Verification
+
+_None yet._
+
+## Child DOX Index
+
+No child AGENTS.md (leaf directory).