docs: reorganize developer documentation

docs/development/validation.md

@@ -0,0 +1,47 @@
+# Validation
+
+Validation should match the change. Do not run expensive broad checks just to look thorough, but do not skip checks that prove the changed boundary still works.
+
+## Docs-only changes
+
+Minimum checks:
+
+```sh
+./tickets.sh doctor
+git diff --check
+```
+
+Useful stale-surface sweeps:
+
+```sh
+STALE_DOC_PATTERN='TODO[.]md|obsolete doc dirs|old ticket surface'
+rg -n "$STALE_DOC_PATTERN" README.md docs crates/*/README.md --glob '!docs/report/**'
+```
+
+## Code changes
+
+Prefer targeted tests first, then broader checks when the touched boundary is central.
+
+Common checks:
+
+```sh
+cargo test --workspace
+cargo test -p <crate>
+cargo check --workspace
+```
+
+Avoid repository-wide formatting churn when a validation failure is caused by pre-existing unrelated formatting.
+
+## Work item checks
+
+Run:
+
+```sh
+./tickets.sh doctor
+```
+
+Use work item review to verify that the implementation satisfies the ticket, not only that the diff looks plausible.
+
+## Current limitation
+
+End-to-end tests that spawn real processes are not yet designed. When changing Pod restoration, socket behavior, or orchestration, compensate with targeted unit/integration tests and concrete manual evidence in the implementation report.