diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c9b7e8..fdaa8e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,8 @@
 ## Unreleased
 
 - `trusted_endpoints`: registered URLs may now contain FastAPI/Express-style path placeholders. `{id}` matches exactly one path segment, `{rest:path}` matches any subtree. Plain URLs without `{` keep exact-match semantics — no migration needed for existing rows. Both `is_trusted_endpoint` and the snapshot tamper-check inside `evaluate_handoff` honor the new syntax. Closes #14.
+- `set_intercept_url_allowlist`: now accepts the same `{id}` / `{rest:path}` placeholders as `trusted_endpoints` (parity, single matching helper used by both code paths). A registered `https://api.example.com/customers/{id}` covers the concrete `https://api.example.com/customers/42` for both intercept recording and the simulation tamper hook. Plain URLs without `{` keep exact-match semantics — zero migration. Closes #20.
+- `json_path` (used by `field_extraction` / `schema_type` / `range_threshold`): now supports array indexing. Use bracket form (`items[0].subject`, `[0].status`) or numeric-segment fallback (`items.0.subject`). Out-of-range indices raise `IndexError` and surface as `CAUGHT` with `"out of range"` in the detail. Pure-dict paths are unchanged. Closes #23.
 - README: new "Getting `PROVABLY_API_KEY` and `PROVABLY_ORG_ID`" subsection walking through sign-up at app.provably.ai → create org → Integrations menu, plus a pointer to provably.ai/docs.
 - **BREAKING:** removed `default_cluster_b_url()` and the `CLUSTER_B_URL` env var — leftovers from the langgraph-demo monorepo extraction with a `localhost:8082` default and opaque "cluster B" naming the SDK has no business assuming. `post_handoff(receiver_url, payload)` (positional arg renamed from `cluster_b_url`) takes the URL directly — supply it from your application's own configuration.
 
diff --git a/src/provably/handoff/eval_modes.py b/src/provably/handoff/eval_modes.py
index 892e532..9acd3bd 100644
--- a/src/provably/handoff/eval_modes.py
+++ b/src/provably/handoff/eval_modes.py
@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import math
+import re
 from typing import Any
 
 import jsonschema
@@ -31,7 +32,7 @@ def evaluate_claim(claim: HandoffClaim, indexed_root: Any) -> dict[str, Any]:
 
     try:
         at_path = _get_by_json_path(indexed_root, claim.json_path)
-    except (KeyError, TypeError, ValueError) as exc:
+    except (KeyError, IndexError, TypeError, ValueError) as exc:
         return {**base, "result": "CAUGHT", "detail": f"json_path: {exc}"}
 
     base["indexed_at_path"] = canonical_json(at_path)
@@ -96,22 +97,62 @@ def _eval_range_threshold(claim: HandoffClaim, at_path: Any, base: dict[str, Any
     return {**base, "result": "PASS"}
 
 
-def _normalize_json_path(path: str) -> str:
-    """Strip JSONPath / Relaxed JSON Pointer prefixes so we only walk plain dot paths.
+_BRACKET_INDEX_RE = re.compile(r"\[(\d+)\]")
+
 
-    Examples: ``"$.userId"`` → ``"userId"``; ``"$"`` / ``""`` → ``""`` (root); ``"a.b"`` unchanged.
+def _normalize_json_path(path: str) -> str:
+    """Strip JSONPath / Relaxed JSON Pointer prefixes and split bracket indices into their
+    own segments so the dot-tokenizer can walk them.
+
+    Examples:
+      - ``"$.userId"`` → ``"userId"``
+      - ``"$"`` / ``""`` → ``""`` (root)
+      - ``"a.b"`` → ``"a.b"`` (unchanged)
+      - ``"items[0].subject"`` → ``"items.[0].subject"`` (bracket lifted to its own segment)
+      - ``"[0].status"`` → ``"[0].status"`` (leading-dot stripped)
     """
     p = (path or "").strip()
     if not p or p == "$":
         return ""
     if p.startswith("$."):
-        return p[2:].strip()
-    if p.startswith("$"):
+        p = p[2:].strip()
+    elif p.startswith("$"):
         # e.g. "$['x']" not supported; bare "$x" is treated as path after $
-        return p[1:].lstrip(".").strip()
+        p = p[1:].lstrip(".").strip()
+    # Lift bracket indices into standalone dot segments so ``items[0]`` becomes
+    # ``items.[0]`` and ``items[0][1]`` becomes ``items.[0].[1]``. The empty-segment
+    # filter in ``_get_by_json_path`` swallows any double-dots this introduces.
+    p = _BRACKET_INDEX_RE.sub(r".[\1]", p).lstrip(".")
     return p
 
 
+def _step_into(cursor: Any, segment: str) -> Any:
+    """Walk one segment.
+
+    - ``[N]`` (bracket form) against a list → ``cursor[N]``.
+    - Numeric segment against a list → ``cursor[N]`` (fallback for ``items.0.foo``).
+    - Any other segment against a dict → ``cursor[segment]``.
+    """
+    bracket = _BRACKET_INDEX_RE.fullmatch(segment)
+    if bracket and isinstance(cursor, list):
+        idx = int(bracket.group(1))
+        if idx >= len(cursor):
+            raise IndexError(f"index {idx} out of range (list has {len(cursor)} elements)")
+        return cursor[idx]
+    if isinstance(cursor, list) and segment.isdigit():
+        idx = int(segment)
+        if idx >= len(cursor):
+            raise IndexError(f"index {idx} out of range (list has {len(cursor)} elements)")
+        return cursor[idx]
+    if isinstance(cursor, dict):
+        if segment not in cursor:
+            raise KeyError(segment)
+        return cursor[segment]
+    raise KeyError(
+        f"expected dict or list at segment {segment!r}, got {type(cursor).__name__}"
+    )
+
+
 def _get_by_json_path(obj: Any, path: str) -> Any:
     rel = _normalize_json_path(path)
     if not rel:
@@ -121,13 +162,7 @@ def _get_by_json_path(obj: Any, path: str) -> Any:
         segment = segment.strip()
         if not segment:
             continue
-        if not isinstance(cursor, dict):
-            raise KeyError(
-                f"expected dict at segment {segment!r}, got {type(cursor).__name__}"
-            )
-        if segment not in cursor:
-            raise KeyError(segment)
-        cursor = cursor[segment]
+        cursor = _step_into(cursor, segment)
     return cursor
 
 
diff --git a/src/provably/intercept/interceptor.py b/src/provably/intercept/interceptor.py
index b3cf4d4..7ec4e0d 100644
--- a/src/provably/intercept/interceptor.py
+++ b/src/provably/intercept/interceptor.py
@@ -29,7 +29,7 @@
     insert_intercept_row,
     request_payload_dict,
 )
-from provably.trusted_endpoints import normalize_url_for_trust
+from provably.trusted_endpoints import _matches_registered, normalize_url_for_trust
 
 _ctx_agent_id: ContextVar[str] = ContextVar("provably_agent_id", default="")
 _ctx_action_name: ContextVar[str] = ContextVar("provably_action_name", default="")
@@ -67,6 +67,12 @@ def set_intercept_url_allowlist(urls: list[str] | None) -> None:
 
     Pass ``None`` to clear. Pass a list to restrict tamper to the run's dashboard endpoints;
     URLs not in the set are not recorded and pass through unchanged.
+
+    Entries support the same FastAPI/Express-style placeholders as the trusted-endpoint
+    registry: ``{name}`` matches one path segment, ``{name:path}`` matches any subtree.
+    A registered ``https://api.example.com/customers/{id}`` matches the concrete URL
+    ``https://api.example.com/customers/42``. Plain URLs without ``{`` keep exact-match
+    semantics.
     """
     global _url_allowlist
     if urls is None:
@@ -78,6 +84,22 @@ def set_intercept_url_allowlist(urls: list[str] | None) -> None:
         _url_allowlist.discard("")
 
 
+def _url_in_allowlist(nurl: str) -> bool:
+    """Membership test for ``_url_allowlist`` that honors pattern entries.
+
+    Exact match is checked first (O(1)). Only on a miss do we iterate over pattern entries
+    (those containing ``{``) — plain-URL allowlists pay no per-request iteration cost.
+    Caller must have already confirmed ``_url_allowlist is not None``.
+    """
+    assert _url_allowlist is not None
+    if nurl in _url_allowlist:
+        return True
+    for entry in _url_allowlist:
+        if "{" in entry and _matches_registered(nurl, entry):
+            return True
+    return False
+
+
 @contextmanager
 def intercept_context(
     *, agent_id: str, action_name: str, intercept_index: int = 0
@@ -262,14 +284,14 @@ def _record_and_maybe_tamper(
     """
     req = request_payload_dict(url, method, req_kwargs)
     nurl = normalize_url_for_trust(str(url))
-    if _url_allowlist is not None and nurl not in _url_allowlist:
+    in_allowlist = _url_allowlist is not None and _url_in_allowlist(nurl)
+    if _url_allowlist is not None and not in_allowlist:
         return response
     if _enabled:
         _insert_row(url, req, raw, method=method)
     # Tamper hook fires only for explicit run endpoints; never for OpenRouter, Provably API,
     # cluster handoff posts (those run with allowlist cleared or off-list).
-    tamper = _url_allowlist is not None and nurl in _url_allowlist
-    mutated = _maybe_transform_body(raw) if tamper else raw
+    mutated = _maybe_transform_body(raw) if in_allowlist else raw
     if mutated is raw:
         return response
     if isinstance(response, requests.Response):
diff --git a/tests/unit/test_eval_modes.py b/tests/unit/test_eval_modes.py
index c772913..dd0ec3c 100644
--- a/tests/unit/test_eval_modes.py
+++ b/tests/unit/test_eval_modes.py
@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import pytest
+
 from provably.handoff.eval_modes import _get_by_json_path, _normalize_json_path, evaluate_claim
 from provably.handoff.types import HandoffClaim
 
@@ -21,6 +23,91 @@ def test_get_by_path_jsonpath() -> None:
     assert _get_by_json_path(obj, "$") == obj
 
 
+# ---------------------------------------------------------------------------
+# Array indexing in json_path (#23): both bracket form and numeric fallback.
+# ---------------------------------------------------------------------------
+
+
+def test_normalize_jsonpath_lifts_brackets_into_segments() -> None:
+    assert _normalize_json_path("items[0].subject") == "items.[0].subject"
+    assert _normalize_json_path("items[0][1]") == "items.[0].[1]"
+    assert _normalize_json_path("[0].status") == "[0].status"
+    assert _normalize_json_path("$.items[2].quantity") == "items.[2].quantity"
+
+
+def test_get_by_path_bracket_indexing_at_root() -> None:
+    assert _get_by_json_path([{"status": "open"}], "[0].status") == "open"
+    assert _get_by_json_path([10, 20, 30], "[1]") == 20
+
+
+def test_get_by_path_bracket_indexing_inside_dict() -> None:
+    obj = {"items": [{"a": 1}, {"a": 2}, {"a": 3}]}
+    assert _get_by_json_path(obj, "items[0].a") == 1
+    assert _get_by_json_path(obj, "items[2].a") == 3
+    assert _get_by_json_path(obj, "$.items[1].a") == 2
+
+
+def test_get_by_path_numeric_segment_fallback_for_lists() -> None:
+    """``items.0.a`` works when cursor is a list — easier shape for naive LLMs."""
+    obj = {"items": [{"a": 1}, {"a": 2}]}
+    assert _get_by_json_path(obj, "items.0.a") == 1
+    assert _get_by_json_path(obj, "items.1.a") == 2
+
+
+def test_get_by_path_nested_lists() -> None:
+    """Bracket form chains: list of lists of dicts."""
+    obj = {"matrix": [[{"v": "a"}, {"v": "b"}], [{"v": "c"}]]}
+    assert _get_by_json_path(obj, "matrix[0][1].v") == "b"
+    assert _get_by_json_path(obj, "matrix[1][0].v") == "c"
+
+
+def test_get_by_path_index_out_of_range_raises_indexerror() -> None:
+    with pytest.raises(IndexError, match="out of range"):
+        _get_by_json_path([{"a": 1}], "[5].a")
+    with pytest.raises(IndexError, match="out of range"):
+        _get_by_json_path({"items": [1, 2]}, "items[5]")
+
+
+def test_get_by_path_dict_segment_against_list_still_raises_keyerror() -> None:
+    """If the path expects a dict-like step but cursor is a list (and the segment isn't
+    numeric or bracket form), we still raise — old error class preserved."""
+    with pytest.raises(KeyError):
+        _get_by_json_path({"a": [1, 2]}, "a.b")
+
+
+def test_get_by_path_existing_dict_paths_still_work() -> None:
+    """Regression: nothing about pure-dict walks should change."""
+    assert _get_by_json_path({"plan": "Enterprise"}, "plan") == "Enterprise"
+    assert _get_by_json_path({"a": {"b": 1}}, "a.b") == 1
+
+
+def test_field_extraction_pass_with_array_index() -> None:
+    """End-to-end via the real evaluator: list-shaped indexed value, claim against ``[0].status``."""
+    claim = HandoffClaim(
+        action_name="list_open_tickets",
+        claimed_value="open",
+        query_record_id="q1",
+        verification_mode="field_extraction",
+        json_path="[0].status",
+    )
+    indexed = [{"status": "open", "id": 42}, {"status": "closed", "id": 41}]
+    v = evaluate_claim(claim, indexed)
+    assert v["result"] == "PASS", v
+
+
+def test_field_extraction_caught_when_index_out_of_range() -> None:
+    claim = HandoffClaim(
+        action_name="list_open_tickets",
+        claimed_value="open",
+        query_record_id="q1",
+        verification_mode="field_extraction",
+        json_path="[7].status",
+    )
+    v = evaluate_claim(claim, [{"status": "open"}])
+    assert v["result"] == "CAUGHT"
+    assert "out of range" in v["detail"]
+
+
 def test_schema_type_passes_with_dollar_path() -> None:
     """Regression: LLM emits JSONPath ``$.userId``; we must not index ``['$']``."""
     claim = HandoffClaim(
diff --git a/tests/unit/test_interceptor.py b/tests/unit/test_interceptor.py
index 9ab09f5..518e1e7 100644
--- a/tests/unit/test_interceptor.py
+++ b/tests/unit/test_interceptor.py
@@ -86,6 +86,105 @@ def fake_insert(url: str, *_a: Any, **_k: Any) -> None:
         interceptor.set_intercept_url_allowlist(None)
 
 
+# ---------------------------------------------------------------------------
+# Allowlist pattern matching ({id} / {path:path} parity with trusted_endpoints)
+# ---------------------------------------------------------------------------
+
+
+def _attach_with_pattern_allowlist(
+    monkeypatch: Any, allowlist_entries: list[str], call_url: str
+) -> tuple[list[str], list[Any]]:
+    """Helper: install a pattern allowlist, run _attach against ``call_url``, return
+    (recorded URLs, tamper-hook calls)."""
+    recorded: list[str] = []
+    tampered: list[Any] = []
+
+    monkeypatch.setattr(
+        interceptor, "_insert_row", lambda url, *_a, **_k: recorded.append(url)
+    )
+    monkeypatch.setattr(
+        interceptor, "_maybe_transform_body", lambda raw: tampered.append(raw) or raw
+    )
+    monkeypatch.setattr(interceptor, "_enabled", True)
+    try:
+        interceptor.set_intercept_url_allowlist(allowlist_entries)
+        resp = requests.Response()
+        resp.status_code = 200
+        resp._content = b'{"ok": true}'
+        resp.encoding = "utf-8"
+        interceptor._attach(resp, call_url, "GET", {})
+    finally:
+        interceptor.set_intercept_url_allowlist(None)
+    return recorded, tampered
+
+
+def test_allowlist_pattern_matches_concrete_url(monkeypatch: Any) -> None:
+    """Registered ``/customers/{id}`` matches the concrete ``/customers/42`` URL — both
+    recorded and tamper-hooked."""
+    recorded, tampered = _attach_with_pattern_allowlist(
+        monkeypatch,
+        ["https://api.example.com/customers/{id}"],
+        "https://api.example.com/customers/42",
+    )
+    assert recorded == ["https://api.example.com/customers/42"]
+    assert len(tampered) == 1
+
+
+def test_allowlist_pattern_rejects_extra_segment(monkeypatch: Any) -> None:
+    """Registered ``/customers/{id}`` does NOT match ``/customers/42/orders``
+    (single-segment placeholder)."""
+    recorded, tampered = _attach_with_pattern_allowlist(
+        monkeypatch,
+        ["https://api.example.com/customers/{id}"],
+        "https://api.example.com/customers/42/orders",
+    )
+    assert recorded == []
+    assert tampered == []
+
+
+def test_allowlist_path_placeholder_matches_subtree(monkeypatch: Any) -> None:
+    """``{rest:path}`` covers any subtree, including nested segments."""
+    recorded, _ = _attach_with_pattern_allowlist(
+        monkeypatch,
+        ["https://api.example.com/customers/{rest:path}"],
+        "https://api.example.com/customers/42/orders/9",
+    )
+    assert recorded == ["https://api.example.com/customers/42/orders/9"]
+
+
+def test_allowlist_mixed_exact_and_pattern(monkeypatch: Any) -> None:
+    """An allowlist with both exact URLs and patterns: each entry retains its semantics."""
+    # Exact entry hits exactly; pattern entry hits its pattern; unrelated URL is rejected.
+    for url, expected_recorded in [
+        ("https://api.example.com/health", True),  # exact match
+        ("https://api.example.com/customers/9", True),  # pattern match
+        ("https://api.example.com/customers/9/orders", False),  # past pattern
+        ("https://api.example.com/other", False),  # unrelated
+    ]:
+        recorded, _ = _attach_with_pattern_allowlist(
+            monkeypatch,
+            [
+                "https://api.example.com/health",
+                "https://api.example.com/customers/{id}",
+            ],
+            url,
+        )
+        assert (recorded == [url]) is expected_recorded, (
+            f"url={url!r}: expected_recorded={expected_recorded}, got recorded={recorded}"
+        )
+
+
+def test_allowlist_plain_url_still_uses_exact_match(monkeypatch: Any) -> None:
+    """An allowlist entry without ``{`` keeps exact-match semantics — no perf regression for
+    the common case and no accidental prefix match."""
+    recorded, _ = _attach_with_pattern_allowlist(
+        monkeypatch,
+        ["https://api.example.com/customers"],  # no placeholders → exact-only
+        "https://api.example.com/customers/42",
+    )
+    assert recorded == []
+
+
 # ---------------------------------------------------------------------------
 # Phase 1 additions: Client.send / AsyncClient.send / Session.send coverage,
 # re-entry guard, and self-egress exemption.