diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b215a10..245475b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -14,3 +14,31 @@ The [documentation index](Documentation/README.md) links current architecture
 and reference material. Agent work routes live in AGENTS.md; public usage lives
 in the root README. GitHub collaboration files belong in .github/ and contributor
 policy belongs in root governance files. Execution notes belong in .agent/.
+
+## Repository closeout
+
+Use the default branch for daily integration and a task branch or isolated
+worktree for changes. Before cleanup, inspect local changes, worktree owners,
+open pull requests and the accepted source revision. Preserve unrelated source,
+credentials, runtime state and non-generated ignored files; never reset, clean
+or stash another task's work to make a checkout appear clean.
+
+After delivery, fast-forward only a clean integration checkout. Retire a task
+branch only when its tip is in the accepted default branch or its exact head
+matches a merged pull request whose merge is reachable there. Preserve unique
+work with a documented reconciliation and independently verified recovery
+bundle before retiring its directory. Remove owned worktrees through Git, or
+through the managing application's archive operation for managed worktrees.
+
+Build caches in the daily checkout may remain useful. Remove inactive duplicate
+task caches, package staging and disposable test outputs after checking their
+owner and running references. Preserve source inputs, immutable release
+artifacts, necessary failure/acceptance evidence and required rollback state.
+Keep local progress and recovery inventories under ignored `.agent/`; current
+product behavior must remain understandable from committed documentation.
+
+A merged source change, a validated package and a published release have
+different identities. Record the exact source and artifact/check evidence at
+handoff. Documentation or repository cleanup alone does not require a product
+release; published tags and assets remain immutable. Active dependency-update
+pull requests are reviewed maintenance work, not disposable cleanup residue.