diff --git a/.claude/scripts/merge-ready.sh b/.claude/scripts/merge-ready.sh
index ec6498c..74e1ee1 100644
--- a/.claude/scripts/merge-ready.sh
+++ b/.claude/scripts/merge-ready.sh
@@ -75,12 +75,29 @@ decide() {
 
 merged=0; skipped=0
 for n in $(gh pr list -R "$repo" --base "$base" --state open --json number -q '.[].number'); do
-  data="$(gh pr view "$n" -R "$repo" --json number,title,isDraft,baseRefName,mergeable,reviews,statusCheckRollup,commits)"
+  data="$(gh pr view "$n" -R "$repo" --json number,title,isDraft,baseRefName,headRefName,mergeable,reviews,statusCheckRollup,commits)"
   verdict="$(printf '%s' "$data" | decide)"
   title="$(printf '%s' "$data" | node -e 'process.stdout.write((JSON.parse(require("fs").readFileSync(0,"utf8")).title)||"")')"
+  head_branch="$(printf '%s' "$data" | node -e 'process.stdout.write((JSON.parse(require("fs").readFileSync(0,"utf8")).headRefName)||"")')"
   if [ "$verdict" = "MERGE" ]; then
     if gh pr merge "$n" -R "$repo" --merge --delete-branch >/dev/null 2>&1; then
       echo "{\"pr\":$n,\"action\":\"merged\",\"title\":\"$title\"}"; merged=$((merged+1))
+      # Auto-cleanup (issue #91): the merged branch's local worktree + local
+      # branch are now stale. worktree-cleanup.sh applies its OWN safety
+      # rails (worker-path naming, clean tree, fully merged into $base) and
+      # NEVER forces — a "skip" line from it is expected and fine, just
+      # tag it with the PR number and pass it through.
+      if [ -n "$head_branch" ]; then
+        while IFS= read -r cleanup_line; do
+          [ -z "$cleanup_line" ] && continue
+          printf '%s\n' "$cleanup_line" | node -e '
+            const pr = process.argv[1];
+            const obj = JSON.parse(require("fs").readFileSync(0,"utf8"));
+            obj.pr = Number(pr);
+            console.log(JSON.stringify(obj));
+          ' "$n"
+        done < <(bash "$script_dir/worktree-cleanup.sh" "$base" "$head_branch")
+      fi
     else
       echo "{\"pr\":$n,\"action\":\"merge-failed\",\"title\":\"$title\"}"
     fi
diff --git a/.claude/scripts/worktree-cleanup.sh b/.claude/scripts/worktree-cleanup.sh
new file mode 100755
index 0000000..29e4599
--- /dev/null
+++ b/.claude/scripts/worktree-cleanup.sh
@@ -0,0 +1,151 @@
+#!/usr/bin/env bash
+# worktree-cleanup.sh — after merge-ready.sh merges a PR, remove the worker's
+# now-dead worktree + delete its local branch, so `.claude/worktrees/` and the
+# local branch list don't silently accumulate `prunable` entries forever
+# (issue #91). Factored out of merge-ready.sh so it's independently testable
+# offline (see worktree-cleanup.test.sh) without a real merge or network call.
+#
+# Usage: worktree-cleanup.sh <base-branch> [<branch>...]
+#   <base-branch>  the branch merged PRs land on (e.g. main) — used to decide
+#                   "fully merged" against origin/<base> (falling back to
+#                   local `git branch --merged <base>` if origin is
+#                   unreachable/unset — see merged_via_origin below).
+#   <branch>...    zero or more branch names that were just merged. For each,
+#                   the corresponding worktree (if any) is located via
+#                   `git worktree list --porcelain` and, ONLY if every safety
+#                   rail below holds, the worktree is removed and the local
+#                   branch deleted.
+#
+# Safety rails — ALL must hold, else the branch is SKIPPED with a logged
+# reason and left untouched. NEVER `--force`, NEVER `git branch -D`:
+#   - the branch has an associated worktree at all
+#   - that worktree's path matches the worker naming convention:
+#     .claude/worktrees/agent-* or .claude/worktrees/issue-* (rejects the
+#     main worktree and anything else, e.g. a hand-made worktree)
+#   - the worktree has a clean tree (`git status --porcelain` empty)
+#   - the branch is fully merged into <base-branch> — checked against the
+#     fetched origin/<base> (authoritative; see merged_via_origin) OR local
+#     `git branch --merged <base>` (issue #91 follow-up: merge-ready.sh calls
+#     this script right after `gh pr merge`, which only merges on the
+#     remote, so local <base> is stale at this point — checking it alone
+#     would report every just-merged branch as unmerged forever)
+#   - `git worktree remove` succeeds on its own steam (never forced); the
+#     branch is then deleted via `git branch -d` if it agrees, or — only when
+#     merged_via_origin independently verified the merge — via a direct ref
+#     delete (never `-D`/`--force`, never for an unverified branch)
+#
+# Emits ONE JSON line per branch on stdout, either:
+#   {"branch":"<name>","worktree_removed":"<path>","branch_deleted":"<name>"}
+#   {"branch":"<name>","worktree_removed":"<path>","action":"skip","reason":"branch-delete-failed"}
+#   {"branch":"<name>","action":"skip","reason":"<why>"}
+# consistent with merge-ready.sh's existing JSON-lines output style.
+set -uo pipefail
+
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=resolve-roots.sh
+. "$script_dir/resolve-roots.sh"
+
+base="${1:?usage: worktree-cleanup.sh <base-branch> [<branch>...]}"
+shift || true
+
+json_escape() {
+  node -e 'process.stdout.write(JSON.stringify(process.argv[1]))' "$1"
+}
+
+# Map a branch name -> its worktree's absolute path, by parsing
+# `git worktree list --porcelain` records:
+#   worktree <path>
+#   HEAD <sha>
+#   branch refs/heads/<name>      (absent when detached)
+#   <blank line separates records>
+worktree_for_branch() {
+  local want="$1"
+  git -C "$root" worktree list --porcelain | node -e '
+    const want = process.argv[1];
+    const chunks = require("fs").readFileSync(0, "utf8").split(/\n\n+/);
+    for (const c of chunks) {
+      let path = null, branch = null;
+      for (const l of c.split("\n")) {
+        if (l.startsWith("worktree ")) path = l.slice("worktree ".length);
+        if (l.startsWith("branch refs/heads/")) branch = l.slice("branch refs/heads/".length);
+      }
+      if (path && branch === want) { process.stdout.write(path); process.exit(0); }
+    }
+  ' "$want"
+}
+
+is_worker_path() {
+  case "$1" in
+    */.claude/worktrees/agent-*|*/.claude/worktrees/issue-*) return 0 ;;
+    *) return 1 ;;
+  esac
+}
+
+skip() {
+  local branch="$1" reason="$2"
+  echo "{\"branch\":$(json_escape "$branch"),\"action\":\"skip\",\"reason\":$(json_escape "$reason")}"
+}
+
+# merge-ready.sh invokes this script IMMEDIATELY after `gh pr merge` succeeds
+# — that merges on the REMOTE only. The LOCAL base branch isn't fast-forwarded
+# until merge-ready.sh's post-loop local_sync block, which runs AFTER this
+# script returns. A plain local `git branch --merged "$base"` check therefore
+# always reports the just-merged branch as unmerged, so cleanup never fires
+# (issue #91 follow-up — the feature was inert in production). Fetch the
+# authoritative remote base once up front and prefer ancestry against it;
+# fall back to the local check (previous behavior) when the fetch is
+# unavailable (offline) or origin/$base doesn't exist yet.
+git -C "$root" fetch --quiet origin "$base" 2>/dev/null || true
+
+# True iff $1 is an ancestor of origin/$base — i.e. genuinely merged on the
+# remote — independent of whatever local $base happens to point at right
+# now. Used both as (part of) the merged-ness gate and, if `git branch -d`
+# refuses below because local $base hasn't caught up yet, as the trusted
+# basis for a non-force deletion.
+merged_via_origin() {
+  local branch="$1"
+  git -C "$root" rev-parse --verify --quiet "refs/remotes/origin/$base" >/dev/null 2>&1 \
+    && git -C "$root" merge-base --is-ancestor "$branch" "refs/remotes/origin/$base" 2>/dev/null
+}
+
+for branch in "$@"; do
+  [ -z "$branch" ] && continue
+
+  wt="$(worktree_for_branch "$branch")"
+  if [ -z "$wt" ]; then
+    skip "$branch" "no-worktree"
+    continue
+  fi
+  if ! is_worker_path "$wt"; then
+    skip "$branch" "not-a-worker-worktree-path"
+    continue
+  fi
+  if [ -n "$(git -C "$wt" status --porcelain 2>/dev/null)" ]; then
+    skip "$branch" "worktree-dirty"
+    continue
+  fi
+  # `git branch --merged` prefixes the current branch with `*` and any branch
+  # checked out in ANOTHER linked worktree with `+` — strip both markers
+  # before comparing names. OR'd with merged_via_origin so a branch merged on
+  # the remote but not yet reflected in local $base still counts as merged.
+  if ! merged_via_origin "$branch" \
+     && ! git -C "$root" branch --merged "$base" 2>/dev/null | sed 's/^[*+ ]*//' | grep -qxF "$branch"; then
+    skip "$branch" "branch-not-merged"
+    continue
+  fi
+  if ! git -C "$root" worktree remove "$wt" 2>/dev/null; then
+    skip "$branch" "worktree-remove-failed(dirty-or-locked)"
+    continue
+  fi
+  if git -C "$root" branch -d "$branch" >/dev/null 2>&1; then
+    echo "{\"branch\":$(json_escape "$branch"),\"worktree_removed\":$(json_escape "$wt"),\"branch_deleted\":$(json_escape "$branch")}"
+  elif merged_via_origin "$branch" && git -C "$root" update-ref -d "refs/heads/$branch" 2>/dev/null; then
+    # `git branch -d` refused because it only trusts local $base/upstream,
+    # which hasn't fast-forwarded yet — but we've independently verified via
+    # origin/$base ancestry above that this is genuinely merged, so deleting
+    # the ref directly is safe (still never -D/--force on anything unverified).
+    echo "{\"branch\":$(json_escape "$branch"),\"worktree_removed\":$(json_escape "$wt"),\"branch_deleted\":$(json_escape "$branch")}"
+  else
+    echo "{\"branch\":$(json_escape "$branch"),\"worktree_removed\":$(json_escape "$wt"),\"action\":\"skip\",\"reason\":\"branch-delete-failed(unmerged-elsewhere?)\"}"
+  fi
+done
diff --git a/.claude/scripts/worktree-cleanup.test.sh b/.claude/scripts/worktree-cleanup.test.sh
new file mode 100755
index 0000000..94572d2
--- /dev/null
+++ b/.claude/scripts/worktree-cleanup.test.sh
@@ -0,0 +1,220 @@
+#!/usr/bin/env bash
+# worktree-cleanup.test.sh — offline smoke test for worktree-cleanup.sh
+# (issue #91). Builds a THROWAWAY temp git repo with real `git worktree add`
+# worktrees (no real network, no gh, no real PR merge — scenario 6 uses a
+# local bare repo as a stand-in "origin", never a real remote) and exercises
+# the real worktree-cleanup.sh against it, asserting:
+#   1. merged + clean + matching-name worktree -> removed + branch deleted
+#   2. dirty worktree -> preserved (never touched)
+#   3. unmerged branch -> preserved (never touched)
+#   4. non-matching path (main worktree, and an arbitrary non-worker path)
+#      -> never touched
+#   5. no worktree at all -> skip, no crash
+#   6. PRODUCTION ordering (issue #91 follow-up): merge landed on the
+#      authoritative remote but local base is still stale -> removed + branch
+#      deleted anyway (via origin ancestry, never a forced delete)
+#
+# Exit 0 on success, non-zero if any assertion fails. Runnable bare:
+#   bash .claude/scripts/worktree-cleanup.test.sh
+set -uo pipefail
+
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cleanup_src="$script_dir/worktree-cleanup.sh"
+resolve_roots_src="$script_dir/resolve-roots.sh"
+
+work="$(mktemp -d "${TMPDIR:-/tmp}/worktree-cleanup-test.XXXXXX")"
+trap 'rm -rf "$work"' EXIT
+
+fail=0
+ok=0
+check() {
+  local desc="$1"; shift
+  if "$@"; then
+    ok=$((ok + 1))
+    echo "ok - $desc"
+  else
+    fail=1
+    echo "FAIL - $desc"
+  fi
+}
+
+# Throwaway "consumer project" git repo: real commits + real `git worktree
+# add`, with the REAL worktree-cleanup.sh + resolve-roots.sh copied into its
+# .claude/scripts/ (mirrors loop-tick.test.sh's fixture pattern), so root
+# derivation matches how the script resolves things in production.
+repo="$work/repo"
+mkdir -p "$repo"
+git init -q -b main "$repo"
+git -C "$repo" config user.email "test@example.com"
+git -C "$repo" config user.name "Test"
+echo "seed" > "$repo/README.md"
+git -C "$repo" add README.md
+git -C "$repo" commit -q -m "seed"
+
+mkdir -p "$repo/.claude/scripts"
+cp "$cleanup_src" "$repo/.claude/scripts/worktree-cleanup.sh"
+cp "$resolve_roots_src" "$repo/.claude/scripts/resolve-roots.sh"
+chmod +x "$repo/.claude/scripts/worktree-cleanup.sh"
+
+run_cleanup() {
+  # $1 = base branch, $@[2:] = branch names to attempt cleanup on.
+  ( cd "$repo" && bash "$repo/.claude/scripts/worktree-cleanup.sh" "$@" )
+}
+
+worktree_present() {
+  git -C "$repo" worktree list --porcelain | grep -qF "worktree $1"
+}
+branch_present() {
+  git -C "$repo" branch --list "$1" | grep -q .
+}
+
+# ---------------------------------------------------------------------------
+# Scenario 1: merged + clean + matching-name worktree -> removed + branch
+# deleted.
+# ---------------------------------------------------------------------------
+git -C "$repo" checkout -q -b feat/issue-1-x
+echo "one" > "$repo/file1.txt"
+git -C "$repo" add file1.txt
+git -C "$repo" commit -q -m "feat1"
+git -C "$repo" checkout -q main
+git -C "$repo" merge -q --no-ff feat/issue-1-x -m "merge feat1"
+wt1="$repo/.claude/worktrees/agent-test1"
+git -C "$repo" worktree add -q "$wt1" feat/issue-1-x
+
+out1="$(run_cleanup main feat/issue-1-x)"
+check "scenario 1: emits a JSON line reporting the removal" bash -c 'printf "%s\n" "$1" | grep -q "worktree_removed"' _ "$out1"
+check "scenario 1: worktree_removed path is correct" bash -c 'printf "%s\n" "$1" | grep -qF "\"worktree_removed\":\"$2\""' _ "$out1" "$wt1"
+check "scenario 1: branch_deleted reports the branch name" bash -c 'printf "%s\n" "$1" | grep -qF "\"branch_deleted\":\"feat/issue-1-x\""' _ "$out1"
+check "scenario 1: worktree is actually gone from git worktree list" bash -c '! git -C "$1" worktree list --porcelain | grep -qF "worktree $2"' _ "$repo" "$wt1"
+check "scenario 1: worktree directory removed from disk" bash -c '[ ! -d "$1" ]' _ "$wt1"
+check "scenario 1: local branch actually deleted" bash -c '! git -C "$1" branch --list feat/issue-1-x | grep -q .' _ "$repo"
+
+# ---------------------------------------------------------------------------
+# Scenario 2: dirty worktree -> preserved (never removed, branch never
+# deleted), even though the branch IS fully merged.
+# ---------------------------------------------------------------------------
+git -C "$repo" checkout -q -b feat/issue-2-x
+echo "two" > "$repo/file2.txt"
+git -C "$repo" add file2.txt
+git -C "$repo" commit -q -m "feat2"
+git -C "$repo" checkout -q main
+git -C "$repo" merge -q --no-ff feat/issue-2-x -m "merge feat2"
+wt2="$repo/.claude/worktrees/agent-test2"
+git -C "$repo" worktree add -q "$wt2" feat/issue-2-x
+echo "dirty" >> "$wt2/file2.txt"   # make the worktree dirty
+
+out2="$(run_cleanup main feat/issue-2-x)"
+check "scenario 2: emits a skip with reason worktree-dirty" bash -c 'printf "%s\n" "$1" | grep -qF "\"reason\":\"worktree-dirty\""' _ "$out2"
+check "scenario 2: worktree still present (untouched)" worktree_present "$wt2"
+check "scenario 2: worktree directory still on disk" [ -d "$wt2" ]
+check "scenario 2: branch still present (untouched)" branch_present "feat/issue-2-x"
+
+# ---------------------------------------------------------------------------
+# Scenario 3: unmerged branch -> preserved (clean tree, matching path, but
+# never merged into base).
+# ---------------------------------------------------------------------------
+git -C "$repo" checkout -q -b feat/issue-3-x
+echo "three" > "$repo/file3.txt"
+git -C "$repo" add file3.txt
+git -C "$repo" commit -q -m "feat3 (never merged)"
+git -C "$repo" checkout -q main
+wt3="$repo/.claude/worktrees/agent-test3"
+git -C "$repo" worktree add -q "$wt3" feat/issue-3-x
+
+out3="$(run_cleanup main feat/issue-3-x)"
+check "scenario 3: emits a skip with reason branch-not-merged" bash -c 'printf "%s\n" "$1" | grep -qF "\"reason\":\"branch-not-merged\""' _ "$out3"
+check "scenario 3: worktree still present (untouched)" worktree_present "$wt3"
+check "scenario 3: worktree directory still on disk" [ -d "$wt3" ]
+check "scenario 3: branch still present (untouched)" branch_present "feat/issue-3-x"
+
+# ---------------------------------------------------------------------------
+# Scenario 4a: the base/main branch itself (worktree is the MAIN worktree,
+# not a worker one) -> never touched, even though "main" trivially satisfies
+# "merged into main" and the tree is clean.
+# ---------------------------------------------------------------------------
+out4a="$(run_cleanup main main)"
+check "scenario 4a: emits a skip for the main worktree's own branch" bash -c 'printf "%s\n" "$1" | grep -qF "\"branch\":\"main\""' _ "$out4a"
+check "scenario 4a: reason is not-a-worker-worktree-path" bash -c 'printf "%s\n" "$1" | grep -qF "\"reason\":\"not-a-worker-worktree-path\""' _ "$out4a"
+check "scenario 4a: main worktree itself is untouched" bash -c '[ -d "$1" ] && git -C "$1" rev-parse --show-toplevel >/dev/null 2>&1' _ "$repo"
+
+# ---------------------------------------------------------------------------
+# Scenario 4b: an arbitrary non-worker-naming worktree path (merged + clean,
+# but not .claude/worktrees/agent-* or issue-*) -> never touched.
+# ---------------------------------------------------------------------------
+git -C "$repo" checkout -q -b feat/issue-4-x
+echo "four" > "$repo/file4.txt"
+git -C "$repo" add file4.txt
+git -C "$repo" commit -q -m "feat4"
+git -C "$repo" checkout -q main
+git -C "$repo" merge -q --no-ff feat/issue-4-x -m "merge feat4"
+wt4="$repo/.claude/worktrees/some-random-dir"
+git -C "$repo" worktree add -q "$wt4" feat/issue-4-x
+
+out4b="$(run_cleanup main feat/issue-4-x)"
+check "scenario 4b: emits a skip with reason not-a-worker-worktree-path" bash -c 'printf "%s\n" "$1" | grep -qF "\"reason\":\"not-a-worker-worktree-path\""' _ "$out4b"
+check "scenario 4b: worktree still present (untouched)" worktree_present "$wt4"
+check "scenario 4b: worktree directory still on disk" [ -d "$wt4" ]
+check "scenario 4b: branch still present (untouched)" branch_present "feat/issue-4-x"
+
+# ---------------------------------------------------------------------------
+# Scenario 5: a branch with no worktree at all -> skip:no-worktree, no crash.
+# ---------------------------------------------------------------------------
+git -C "$repo" branch -q feat/issue-5-x-no-worktree
+out5="$(run_cleanup main feat/issue-5-x-no-worktree)"
+check "scenario 5: emits a skip with reason no-worktree" bash -c 'printf "%s\n" "$1" | grep -qF "\"reason\":\"no-worktree\""' _ "$out5"
+
+# ---------------------------------------------------------------------------
+# Scenario 6 (issue #91 follow-up, PRODUCTION ordering): merge-ready.sh calls
+# worktree-cleanup.sh IMMEDIATELY after `gh pr merge` succeeds, which merges
+# on the REMOTE only — local $base isn't fast-forwarded until a block that
+# runs AFTER cleanup. Reproduce that ordering hermetically: a real bare repo
+# stands in for "origin"; the merge is performed and pushed from a SEPARATE
+# clone, so $repo's own local `main` ref is never touched by it. Cleanup must
+# still detect the merge (via origin/$base ancestry) and remove the worktree
+# + delete the branch — without ever advancing local `main` itself, and
+# without ever needing `-D`/`--force`.
+# ---------------------------------------------------------------------------
+origin_bare="$work/origin.git"
+git init -q --bare -b main "$origin_bare"
+git -C "$repo" remote add origin "$origin_bare"
+git -C "$repo" push -q origin main:main
+
+git -C "$repo" checkout -q -b feat/issue-6-x
+echo "six" > "$repo/file6.txt"
+git -C "$repo" add file6.txt
+git -C "$repo" commit -q -m "feat6"
+git -C "$repo" checkout -q main
+git -C "$repo" push -q origin feat/issue-6-x:feat/issue-6-x
+
+# Perform + push the merge from a THIRD, independent clone (mimics GitHub
+# doing the merge server-side) so local `main` in $repo is never advanced.
+remote_work="$work/remote-work"
+git clone -q "$origin_bare" "$remote_work"
+git -C "$remote_work" config user.email "test@example.com"
+git -C "$remote_work" config user.name "Test"
+git -C "$remote_work" checkout -q main
+git -C "$remote_work" merge -q --no-ff origin/feat/issue-6-x -m "merge feat6"
+git -C "$remote_work" push -q origin main:main
+
+local_main_before="$(git -C "$repo" rev-parse main)"
+
+wt6="$repo/.claude/worktrees/agent-test6"
+git -C "$repo" worktree add -q "$wt6" feat/issue-6-x
+
+out6="$(run_cleanup main feat/issue-6-x)"
+check "scenario 6 (sanity): local main is genuinely stale before cleanup runs" bash -c '[ "$1" = "$(git -C "$2" rev-parse main)" ]' _ "$local_main_before" "$repo"
+check "scenario 6: emits a JSON line reporting the removal despite stale local main" bash -c 'printf "%s\n" "$1" | grep -q "worktree_removed"' _ "$out6"
+check "scenario 6: branch_deleted reports the branch name" bash -c 'printf "%s\n" "$1" | grep -qF "\"branch_deleted\":\"feat/issue-6-x\""' _ "$out6"
+check "scenario 6: worktree is actually gone from git worktree list" bash -c '! git -C "$1" worktree list --porcelain | grep -qF "worktree $2"' _ "$repo" "$wt6"
+check "scenario 6: worktree directory removed from disk" bash -c '[ ! -d "$1" ]' _ "$wt6"
+check "scenario 6: local branch actually deleted" bash -c '! git -C "$1" branch --list feat/issue-6-x | grep -q .' _ "$repo"
+check "scenario 6: local main ref itself was never advanced by cleanup" bash -c '[ "$1" = "$(git -C "$2" rev-parse main)" ]' _ "$local_main_before" "$repo"
+
+echo ""
+if [ "$fail" -eq 0 ]; then
+  echo "worktree-cleanup.test.sh: PASS ($ok checks)"
+  exit 0
+else
+  echo "worktree-cleanup.test.sh: FAIL (see FAIL lines above)"
+  exit 1
+fi