diff --git a/docs/llm-workflow-runbooks.md b/docs/llm-workflow-runbooks.md
index 3bcc708..4ea9c13 100644
--- a/docs/llm-workflow-runbooks.md
+++ b/docs/llm-workflow-runbooks.md
@@ -229,6 +229,34 @@ Legacy environment-only setups keep working unchanged until migrated.
 Each runbook names the **profile role** it runs under, the steps, and a safe
 prompt. Confirm the active profile first (`gitea_get_profile` / `gitea_whoami`).
 
+## Work Selection Rule for LLMs
+
+Before starting any issue or PR work, acquire or verify a work lease. Do not
+begin coding, reviewing, fixing, branching, committing, pushing, commenting,
+or creating a PR until you prove the target is not already being worked.
+
+Required checks:
+
+1. List open PRs.
+2. Search for PRs linked to the target issue.
+3. Search local and remote branches for the issue number.
+4. Search registered worktrees for the issue branch.
+5. Check dirty worktrees.
+6. Check active leases or recent handoffs.
+7. Check whether the issue was already completed by a merged PR.
+
+If another active LLM/session owns the lease, stop. Allowed responses:
+continue as the lease owner; review the existing PR if reviewer capability
+allows; produce a handoff; request takeover after lease expiry; stop with
+"work already claimed."
+
+Never create a parallel branch or PR for the same issue unless the old branch
+is proven abandoned and the takeover is recorded.
+
+Gitea-Tools lease gates: `gitea_lock_issue` (fail-closed before author
+mutations), `status:in-progress`, and claim comments. Full portable wording:
+[`skills/llm-project-workflow/SKILL.md`](../skills/llm-project-workflow/SKILL.md).
+
 ## Branch worktree isolation
 
 All LLM implementation and review work happens in an isolated branch worktree
diff --git a/docs/wiki/Workflow.md b/docs/wiki/Workflow.md
index 7722426..708e0a6 100644
--- a/docs/wiki/Workflow.md
+++ b/docs/wiki/Workflow.md
@@ -14,6 +14,9 @@
 
 ## Step 2: Implement issues (author profile)
 
+0. Work Selection Rule — verify a work lease before any mutations (open PRs,
+   issue-linked PRs, branches, worktrees, dirty worktrees, active leases/
+   handoffs, merged-PR completion). Stop if another session owns the lease.
 1. `gitea_resolve_task_capability` for the author task.
 2. `gitea_lock_issue` before implementation mutations.
 3. Claim with `gitea_mark_issue` / `status:in-progress` label.
diff --git a/gitea_mcp_server.py b/gitea_mcp_server.py
index 1c5c186..ebee897 100644
--- a/gitea_mcp_server.py
+++ b/gitea_mcp_server.py
@@ -3460,11 +3460,27 @@ _GUIDE_RULES = {
         "Conflicting or stale PR state (e.g. prior said merged but live open, or head/updated mismatch) is a hard blocker: report it explicitly and stop until live state is unambiguous.",
         "After merge, re-list PRs and re-view the PR (plus verify master contains the merge) before claiming completion.",
     ],
+    "work_selection": (
+        "Before any issue or PR work, acquire or verify a work lease. Do not "
+        "code, review, branch, commit, push, comment, or open a PR until you "
+        "prove the target is not already being worked. Required checks: list "
+        "open PRs; search PRs linked to the issue; search local/remote "
+        "branches for the issue number; search worktrees for the issue "
+        "branch; check dirty worktrees; check active leases or recent "
+        "handoffs; check whether a merged PR already completed the issue. If "
+        "another session owns the lease, stop (continue as owner, review the "
+        "existing PR, hand off, request takeover after expiry, or report "
+        "'work already claimed'). Never create a parallel branch/PR unless "
+        "the old branch is proven abandoned and takeover is recorded. "
+        "gitea_lock_issue is the fail-closed author lease gate."),
 }
 
 _COMMON_WORKFLOWS = [
     "task routing: resolve task capability via gitea_resolve_task_capability "
     "to check required permission/role kind and identify the safe next action.",
+    "work selection: acquire or verify a work lease before any issue/PR work "
+    "(open PRs, linked PRs, branches, worktrees, dirty worktrees, leases, "
+    "merged completion); stop if another session owns the lease.",
     "issue authoring: verify identity, create/claim the issue, keep scope "
     "explicit (remote/org/repo).",
     "implementation: claim issue, branch from fresh master, implement only "
diff --git a/skills/llm-project-workflow/SKILL.md b/skills/llm-project-workflow/SKILL.md
index d8ad9f6..d92aa0b 100644
--- a/skills/llm-project-workflow/SKILL.md
+++ b/skills/llm-project-workflow/SKILL.md
@@ -53,6 +53,42 @@ Additional issue-first rules:
   owner decision.** Do not create a new repository or a new tracker unless
   explicitly approved by the owner.
 
+## Work Selection Rule for LLMs
+
+Before starting any issue or PR work, acquire or verify a work lease.
+
+Do not begin coding, reviewing, fixing, branching, committing, pushing,
+commenting, or creating a PR until you prove the target is not already being
+worked.
+
+Required checks:
+
+1. List open PRs.
+2. Search for PRs linked to the target issue.
+3. Search local and remote branches for the issue number.
+4. Search registered worktrees for the issue branch.
+5. Check dirty worktrees.
+6. Check active leases or recent handoffs.
+7. Check whether the issue was already completed by a merged PR.
+
+If another active LLM/session owns the lease, stop.
+
+Allowed responses:
+
+- continue as the lease owner,
+- review the existing PR if reviewer capability allows,
+- produce a handoff,
+- request takeover after lease expiry,
+- stop with "work already claimed."
+
+Never create a parallel branch or PR for the same issue unless the old branch
+is proven abandoned and the takeover is recorded.
+
+For Gitea-Tools: `gitea_lock_issue` is the fail-closed lease gate before author
+mutations; `status:in-progress` and claim comments are supporting lease signals.
+Use `review_proofs.classify_issue_for_selection` when reporting fresh issue
+selection (#188).
+
 ## B. Isolated worktree rule
 
 **Never implement or review in the main checkout.** The main checkout is for
@@ -142,6 +178,8 @@ Worktree folder = branch with `/` replaced by `-`
 
 ## E. Start-work workflow
 
+0. Acquire or verify a work lease (Work Selection Rule) — complete all seven
+   checks before any claim, branch, or PR work.
 1. Verify the orchestration checkout (right repo, clean tree).
 2. Fetch/prune: `git fetch <remote> --prune`.
 3. Confirm local `master` equals remote `master` (`git rev-list --left-right --count <remote>/master...master` → `0	0`).
diff --git a/skills/llm-project-workflow/templates/start-issue.md b/skills/llm-project-workflow/templates/start-issue.md
index 54933fc..bde01e7 100644
--- a/skills/llm-project-workflow/templates/start-issue.md
+++ b/skills/llm-project-workflow/templates/start-issue.md
@@ -13,6 +13,15 @@ Rules (llm-project-workflow):
 - Do not self-review or self-merge.
 
 Steps:
+0. Work Selection Rule — before any claim, branch, or file edits, acquire or
+   verify a work lease. Required checks: list open PRs; search PRs linked to
+   the target issue; search local/remote branches for the issue number; search
+   registered worktrees for the issue branch; check dirty worktrees; check
+   active leases or recent handoffs; check whether a merged PR already
+   completed the issue. If another session owns the lease, stop (continue only
+   as lease owner, review the existing PR, hand off, request takeover after
+   expiry, or report "work already claimed"). Never open a parallel branch/PR
+   unless the old branch is proven abandoned and takeover is recorded.
 1. Identity Checklist: Before claiming work, verify and state:
    - Required identity/profile for this task: author (allowed to push branches / create PRs)
    - Current authenticated identity (from whoami): <username>
diff --git a/tests/test_operator_guide.py b/tests/test_operator_guide.py
index 80c07f4..01dd46e 100644
--- a/tests/test_operator_guide.py
+++ b/tests/test_operator_guide.py
@@ -132,7 +132,8 @@ class TestControlPlaneGuide(GuideTestBase):
         rules = g["rules"]
         for key in ("hard_stops", "fail_closed", "head_sha_pinning",
                     "merge_confirmation", "redaction", "separation",
-                    "profile_switching", "identity_verification"):
+                    "profile_switching", "identity_verification",
+                    "work_selection"):
             self.assertIn(key, rules)
         self.assertIn("MERGE PR", json.dumps(rules["merge_confirmation"]))
         self.assertTrue(rules["hard_stops"])
diff --git a/tests/test_review_proofs.py b/tests/test_review_proofs.py
index 3965880..e61e98b 100644
--- a/tests/test_review_proofs.py
+++ b/tests/test_review_proofs.py
@@ -1051,6 +1051,8 @@ class TestControllerHandoff(unittest.TestCase):
         self.assertIn("## Controller Handoff", skill)
         self.assertIn("assess_controller_handoff", skill)
         self.assertIn("issue #182", skill)
+        self.assertIn("## Work Selection Rule for LLMs", skill)
+        self.assertIn("work already claimed", skill)
 
     def test_handoff_rejects_none_workspace_mutations_when_local_edits_exist(self):
         # 1. Workspace mutations: none is rejected when local_edits is True