docs: reorganize developer documentation

crates/pod-registry/README.md

@@ -0,0 +1,30 @@
+# pod-registry
+
+## Role
+
+`pod-registry` tracks live Pod process ownership and delegated scope locks at runtime.
+
+## Boundaries
+
+Owns:
+
+- machine-local live Pod registration
+- collision detection for running Pod names
+- delegated scope lock bookkeeping
+- registry cleanup hooks for stopped or unreachable children
+
+Does not own:
+
+- durable Pod metadata (`pod-store`)
+- replayable session logs (`session-store`)
+- socket protocol definitions (`protocol`)
+- project work item state
+
+## Design notes
+
+The registry is a runtime coordination mechanism. It can help decide whether a Pod is live or colliding, but durable visibility/restoration should be backed by Pod metadata when possible.
+
+## See also
+
+- [`../../docs/design/pod-session-state.md`](../../docs/design/pod-session-state.md)
+- [`../../docs/design/tool-permissions-scope.md`](../../docs/design/tool-permissions-scope.md)