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.

infrastructure/AGENTS.md

@@ -0,0 +1,39 @@
+# infrastructure/
+
+## Purpose
+
+Real-world adapters for the correx kernel. Each submodule wires a concrete external system (SQLite, llama.cpp server, TurboVec sidecar, OS shell, SearXNG/web) to the interfaces declared in `core:*`. The root module (`infrastructure/`) contains `InfrastructureModule` — a single factory object that assembles and wires all adapters for use by `apps/*`.
+
+## Ownership
+
+Adapter layer. Depends on `core:*`. No upward dependency on `apps/*` is permitted.
+
+## Local Contracts
+
+- All adapters implement interfaces declared in `core:*` — never invent adapter-specific abstractions visible outside this layer.
+- `InfrastructureModule` is the sole DI assembly point: `apps/*` call its factory functions; they do not instantiate adapters directly.
+- Tool side effects must be captured in events (invariant #5). Adapters must not execute tool side effects silently.
+- Environment observations (filesystem state, network responses, embedder results) must be recorded as events at call time; replay must not re-query the environment (invariants #8, #9).
+- No cross-core imports. Adapters may depend on multiple `core:*` modules but never on sibling `infrastructure:*` modules except through `InfrastructureModule` wiring.
+
+## Work Guidance
+
+- Kotlin error handling: use `runCatching` / sealed domain types; no bare `try-catch`.
+- Blocking I/O goes in `withContext(Dispatchers.IO)`.
+- Imports: verify each is used before finalising a file; remove unused imports.
+
+## Verification
+
+```
+./gradlew :infrastructure:test --rerun-tasks
+./gradlew check
+```
+
+## Child DOX Index
+
+- [artifacts-cas/](artifacts-cas/AGENTS.md) — content-addressable artifact store backed by SQLite index + append-only segment files
+- [inference/](inference/AGENTS.md) — inference provider registry and llama.cpp adapter (model lifecycle, embedder, tokenizer)
+- [persistence/](persistence/AGENTS.md) — SQLite event store and in-memory event store; artifact repository projection
+- [router/](router/AGENTS.md) — L3 memory adapter (TurboVec Python sidecar) for cross-session router memory
+- [tools/](tools/AGENTS.md) — tool registry, sandboxed executor, shell/web/task/filesystem tool implementations
+- [workflow/](workflow/AGENTS.md) — TOML workflow loader, prompt loader, execution plan compiler