Merge current main while preserving governance repairs

Why: main advanced with merged-task-name and legacy evidence guards during this task.

Evidence: SELF 44 lifecycle regressions pass after resolving both hunks; independent review repairs are recorded in the task card.

Impact: retains both task-start protections and the stronger JSON/legacy receipt reader, without rewriting either branch history.

Refs: Dev PR #211 and #212; .task/feature-governance-reliability.md

scripts/task.sh

@@ -118,13 +118,22 @@ cmd_precheck() {
 
 cmd_start() {
   need_repo
-  local name="${1:-}"; [ -n "$name" ] || die "usage: task.sh start <feature|fix|hotfix>/<slug>"
+  local name="${1:-}"; [ -n "$name" ] || die "usage: task.sh start <feature|fix|hotfix|release>/<slug>"
   echo "$name" | grep -qE '^(feature|fix|hotfix|release)/[A-Za-z0-9._-]+$' || die "branch name must match (feature|fix|hotfix|release)/<slug>"
   fetch_target
   [ -n "${PRECHECK_RECEIPT:-}" ] || die "PRECHECK_RECEIPT required: capture RECEIPT=/tmp/task-precheck.json CMD='make precheck' make evidence first"
   PRECHECK_RECEIPT=$(realpath -- "$PRECHECK_RECEIPT")
   VALIDATE_RECEIPT="$PRECHECK_RECEIPT" bash "${SCRIPT_DIR}/evidence.sh"
   check_worktree before-sync
+  # 已合入的同名分支不得重建（2026-10-05 实测：合入后再 task-start 同名会从新 main 长出
+  # 第二段历史，空卡覆盖已合入任务卡，两轮证据差点丢失）。复核/追加沿用原分支或换新 slug。
+  local guard_ref
+  for guard_ref in "refs/heads/${name}" "refs/remotes/origin/${name}"; do
+    if git rev-parse -q --verify "${guard_ref}" >/dev/null \
+      && git merge-base --is-ancestor "${guard_ref}" "origin/${TARGET_BRANCH}"; then
+      die "branch ${name} already merged into origin/${TARGET_BRANCH} — reuse the original branch or pick a new slug (task-start must not recreate merged cards)"
+    fi
+  done
   [ "$(git status --porcelain | { grep -v '^.. \.zcode/' || true; } | wc -l)" -eq 0 ] || die "dirty tree — resolve first (precheck verdict BUSY)"
   [ "$(git submodule status --recursive 2>/dev/null | { grep -cE '^\+|^U' || true; })" -eq 0 ] || die "submodule drift/conflict — resolve first (precheck verdict BUSY)"
   git merge-base --is-ancestor "origin/${TARGET_BRANCH}" HEAD || die "local ${TARGET_BRANCH} behind origin — pull --ff-only first"