diff --git a/scripts/orchestrator-deploy-hook.sh b/scripts/orchestrator-deploy-hook.sh
index 68be4d6..75b855b 100755
--- a/scripts/orchestrator-deploy-hook.sh
+++ b/scripts/orchestrator-deploy-hook.sh
@@ -13,11 +13,24 @@
 #                      When set, the prevalidated (staging) image is retagged onto
 #                      TARGET_IMAGE instead of rebuilding — guarantees prod runs the
 #                      exact artefact that passed staging (no `docker build`).
+#   EXPECTED_REVISION- expected git SHA of SOURCE_IMAGE (default: unset; ORCH-58)
+#                      Strategy-B fail-closed provenance guard: when set, the
+#                      SOURCE_IMAGE's org.opencontainers.image.revision label MUST
+#                      equal this value before the BUILD-ONCE retag, else exit 1
+#                      (a stale image is never promoted). Unset -> no check (legacy).
+#   GIT_SHA          - --build-staging build-arg     (default: unset; ORCH-58)
+#                      Commit stamped into the rebuilt staging image's revision
+#                      label. Supplied by the caller (validated commit) — NOT
+#                      recomputed from the host clone's HEAD.
+#   BUILD_CONTEXT    - --build-staging build context (default: $REPO; ORCH-58)
+#                      Host worktree of the validated commit; the staging image is
+#                      rebuilt FROM this tree (not the prod clone on main).
 #   LOG              - log file path                (default: /var/log/orchestrator/deploy-hook.log)
 #
 # Usage:
-#   ./orchestrator-deploy-hook.sh [--deploy]    # normal deploy (default)
-#   ./orchestrator-deploy-hook.sh --rollback    # manual rollback
+#   ./orchestrator-deploy-hook.sh [--deploy]        # normal deploy (default)
+#   ./orchestrator-deploy-hook.sh --rollback        # manual rollback
+#   ./orchestrator-deploy-hook.sh --build-staging   # ORCH-58: rebuild staging image (8501)
 
 set -euo pipefail
 
@@ -123,17 +136,6 @@ do_rollback() {
 # ============================================================================
 # MANUAL --rollback mode
 # ============================================================================
-if [[ "${1:-}" == "--build-staging" ]]; then
-    # Strategy-A rebuild mode (ORCH-58): rebuild the staging image stamping
-    # the validated commit SHA into the OCI revision label so the provenance
-    # guard above can fail-closed on it during the subsequent prod retag.
-    GIT_SHA=$(git rev-parse HEAD)
-    log "BUILD-STAGING: rebuilding $TARGET_IMAGE stamping GIT_SHA=$GIT_SHA"
-    docker build --build-arg GIT_SHA="$GIT_SHA" -t "$TARGET_IMAGE" "$REPO" >> "$LOG" 2>&1
-    log "BUILD-STAGING: built $TARGET_IMAGE (revision=$GIT_SHA)"
-    exit 0
-fi
-
 if [[ "${1:-}" == "--rollback" ]]; then
     log "Manual ROLLBACK requested"
     if do_rollback; then
@@ -145,6 +147,41 @@ if [[ "${1:-}" == "--rollback" ]]; then
     fi
 fi
 
+# ============================================================================
+# --build-staging mode (ORCH-58, Strategy A): rebuild the STAGING image from the
+# VALIDATED commit and recreate 8501, so the artefact we validate is the EXACT one
+# later BUILD-ONCE retagged to prod (INV-FRESH). Builds/recreates STAGING ONLY
+# (8501) — never prod (8500). Same exit-code contract (0 = healthy, !=0 = failed).
+#
+# Uses the caller-supplied GIT_SHA + BUILD_CONTEXT (the validated worktree) — it
+# must NOT recompute HEAD from $REPO (the prod clone on `main`): on the
+# deploy-staging -> deploy edge the PR is not yet merged, so `main` HEAD != the
+# validated SHA, which would stamp the wrong revision label and deadlock the
+# Strategy-B guard on every valid self-deploy.
+# ============================================================================
+if [[ "${1:-}" == "--build-staging" ]]; then
+    BUILD_CONTEXT="${BUILD_CONTEXT:-$REPO}"
+    GIT_SHA="${GIT_SHA:-}"
+    log "BUILD-STAGING: rebuilding $TARGET_IMAGE from $BUILD_CONTEXT (GIT_SHA=$GIT_SHA, service=$TARGET_SERVICE, port=$TARGET_PORT)"
+    if ! docker build --build-arg GIT_SHA="$GIT_SHA" -t "$TARGET_IMAGE" "$BUILD_CONTEXT" >> "$LOG" 2>&1; then
+        log "BUILD-STAGING: docker build failed - aborting (exit 1)"
+        exit 1
+    fi
+    log "BUILD-STAGING: recreating $TARGET_SERVICE (profile=$COMPOSE_PROFILE) on the fresh image"
+    if [[ -n "$COMPOSE_PROFILE" ]]; then
+        docker compose --profile "$COMPOSE_PROFILE" up -d --no-build "$TARGET_SERVICE" >> "$LOG" 2>&1
+    else
+        docker compose up -d --no-build "$TARGET_SERVICE" >> "$LOG" 2>&1
+    fi
+    log "BUILD-STAGING: running health-check on port $TARGET_PORT (10x6s)"
+    if health_check 10 6 "build-staging-health"; then
+        log "BUILD-STAGING: $TARGET_SERVICE healthy on the fresh image (exit 0)"
+        exit 0
+    fi
+    log "BUILD-STAGING: health FAILED after rebuild (exit 1)"
+    exit 1
+fi
+
 # ============================================================================
 # NORMAL DEPLOY mode (--deploy or no argument)
 # ============================================================================
diff --git a/src/image_freshness.py b/src/image_freshness.py
index 574d54b..4cdd43e 100644
--- a/src/image_freshness.py
+++ b/src/image_freshness.py
@@ -248,6 +248,13 @@ def rebuild_staging_image(repo: str, branch: str, sha: str) -> tuple[bool, str]:
     if not target:
         return False, "no ssh host configured for staging rebuild"
     host_ctx = _host_worktree_path(repo, branch)
+    # We pass ONLY GIT_SHA (validated commit -> revision label, the shared anchor
+    # with Strategy B), BUILD_CONTEXT (the validated worktree to build FROM) and
+    # TARGET_IMAGE (the staging image name to retag in prod later). COMPOSE_PROFILE
+    # / TARGET_SERVICE / TARGET_PORT are deliberately omitted so the hook keeps its
+    # built-in STAGING defaults (profile=staging, orchestrator-staging, 8501): this
+    # rebuild/recreate must touch STAGING ONLY (8501), NEVER prod (8500) (AC-9), and
+    # the prod defaults are never reachable on this path.
     env_assignments = (
         f"GIT_SHA={shlex.quote(sha)} "
         f"BUILD_CONTEXT={shlex.quote(host_ctx)} "
diff --git a/tests/test_deploy_hook_provenance.py b/tests/test_deploy_hook_provenance.py
index 02c048b..24416a1 100644
--- a/tests/test_deploy_hook_provenance.py
+++ b/tests/test_deploy_hook_provenance.py
@@ -17,6 +17,17 @@ _HOOK = _ROOT / "scripts" / "orchestrator-deploy-hook.sh"
 _DOCKERFILE = _ROOT / "Dockerfile"
 
 
+def _build_staging_block() -> str:
+    """Return only the body of the hook's ``--build-staging`` branch, so the
+    contract assertions below cannot be satisfied by lookalike strings elsewhere
+    in the script (e.g. the NORMAL DEPLOY recreate). The block runs from the
+    ``--build-staging`` guard up to the NORMAL DEPLOY section header."""
+    text = _HOOK.read_text(encoding="utf-8")
+    start = text.index('"${1:-}" == "--build-staging"')
+    end = text.index("NORMAL DEPLOY mode", start)
+    return text[start:end]
+
+
 # ---------------------------------------------------------------------------
 # TC-07: hook fail-closed provenance guard + --build-staging rebuild mode
 # ---------------------------------------------------------------------------
@@ -49,6 +60,41 @@ def test_tc07_build_staging_mode_stamps_git_sha():
     assert 'docker build --build-arg GIT_SHA="$GIT_SHA"' in text
 
 
+def test_tc07_build_staging_builds_from_caller_context_not_repo():
+    """Contract (caller <-> hook): --build-staging must build from the
+    caller-supplied BUILD_CONTEXT (the validated worktree), NOT the prod clone.
+
+    Regression guard for the P0 deadlock: the block must honour the caller's
+    GIT_SHA (BUILD_CONTEXT/GIT_SHA defaulting) and must NOT recompute the SHA
+    from the host clone's HEAD (`git rev-parse HEAD`) — on the
+    deploy-staging -> deploy edge `main` HEAD != validated SHA, which would
+    stamp the wrong revision label and deadlock the Strategy-B guard.
+    """
+    block = _build_staging_block()
+    # Build context is the caller-supplied worktree, defaulting to $REPO.
+    assert 'BUILD_CONTEXT="${BUILD_CONTEXT:-$REPO}"' in block
+    assert 'docker build --build-arg GIT_SHA="$GIT_SHA" -t "$TARGET_IMAGE" "$BUILD_CONTEXT"' in block
+    # Honour the caller's GIT_SHA; never hard-build against the prod clone.
+    assert 'GIT_SHA="${GIT_SHA:-}"' in block
+    assert 'docker build --build-arg GIT_SHA="$GIT_SHA" -t "$TARGET_IMAGE" "$REPO"' not in block
+    # Must NOT recompute the validated SHA from the host clone's HEAD.
+    assert "git rev-parse HEAD" not in block
+
+
+def test_tc07_build_staging_recreates_and_health_checks_8501():
+    """AC-4: --build-staging must recreate the staging container on the fresh
+    image and validate it (health-check), so rebuild_staging_image's rc=0 truly
+    means "rebuilt AND healthy". A bare `docker build` + exit 0 would make the
+    freshness verdict a lie."""
+    block = _build_staging_block()
+    # Recreate the staging service on the freshly built image.
+    assert 'docker compose --profile "$COMPOSE_PROFILE" up -d --no-build "$TARGET_SERVICE"' in block
+    # Validate the fresh container before reporting success.
+    assert 'health_check 10 6 "build-staging-health"' in block
+    # Health failure surfaces as a non-zero exit (FAILED contract preserved).
+    assert "exit 1" in block
+
+
 # ---------------------------------------------------------------------------
 # TC-08: Dockerfile stamps the OCI revision label from a build-arg
 # ---------------------------------------------------------------------------