diff --git a/.github/workflows/inspect-longport-token-expiry.yml b/.github/workflows/inspect-longport-token-expiry.yml
new file mode 100644
index 0000000..21efb9c
--- /dev/null
+++ b/.github/workflows/inspect-longport-token-expiry.yml
@@ -0,0 +1,67 @@
+name: Inspect LongPort Token Expiry
+
+# Read-only: decode JWT exp from Secret Manager token secrets.
+# Never calls /v1/token/refresh, never adds SM versions, never prints secret values.
+on:
+  workflow_dispatch:
+    inputs:
+      target:
+        description: "Account target whose Access Token JWT expiry to inspect."
+        required: true
+        type: choice
+        options:
+          - paper
+          - hk
+          - sg
+      warn_days:
+        description: "Fail when days remaining is below this threshold."
+        required: false
+        type: string
+        default: "30"
+
+permissions:
+  contents: read
+
+concurrency:
+  group: inspect-longport-token-expiry-${{ inputs.target }}
+  cancel-in-progress: false
+
+jobs:
+  inspect:
+    if: github.repository == 'QuantStrategyLab/LongBridgePlatform' && github.ref == 'refs/heads/main'
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    permissions:
+      contents: read
+      id-token: write
+    env:
+      GCP_PROJECT_ID: longbridgequant
+      GCP_WORKLOAD_IDENTITY_PROVIDER: projects/252919773759/locations/global/workloadIdentityPools/github-actions/providers/github-main
+      GCP_WORKLOAD_IDENTITY_SERVICE_ACCOUNT: longbridge-platform-deploy@longbridgequant.iam.gserviceaccount.com
+      TARGET: ${{ inputs.target }}
+      WARN_DAYS: ${{ inputs.warn_days }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Authenticate to Google Cloud (deploy SA)
+        uses: google-github-actions/auth@v3
+        with:
+          workload_identity_provider: ${{ env.GCP_WORKLOAD_IDENTITY_PROVIDER }}
+          service_account: ${{ env.GCP_WORKLOAD_IDENTITY_SERVICE_ACCOUNT }}
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.12"
+
+      - name: Install Secret Manager client
+        run: python -m pip install --quiet 'google-cloud-secret-manager>=2.20'
+
+      - name: Inspect token expiry (names + days only)
+        run: |
+          set -euo pipefail
+          python scripts/inspect_longport_token_expiry.py \
+            --project "$GCP_PROJECT_ID" \
+            --target "$TARGET" \
+            --warn-days "$WARN_DAYS" | tee "$GITHUB_STEP_SUMMARY"
diff --git a/docs/longport_token_refresh_runbook.md b/docs/longport_token_refresh_runbook.md
new file mode 100644
index 0000000..e11bd48
--- /dev/null
+++ b/docs/longport_token_refresh_runbook.md
@@ -0,0 +1,106 @@
+# LongPort Access Token durability (paper / HK / SG)
+
+## Recommendation (one line)
+
+**Prefer path A now:** keep Legacy App Key/Secret/Access Token, fix and schedule **pre-expiry** refresh into Secret Manager (paper → SG → HK last); defer OAuth2 (path B) until A is durable and SDK 4.x is planned.
+
+## Why this exists
+
+LongPort Legacy Access Tokens expire (docs: ~90 days / three months). After expiry, `GET /v1/token/refresh` returns **401003** and **cannot** revive the token; recovery is Developer Portal reset + Secret Manager rotate (HK was healed this way on 2026-10-09). Probe/heartbeat and paused strategy must not be the only auth paths.
+
+Authoritative vendor docs:
+
+- [Getting Started (Legacy refresh + OAuth)](https://open.longportapp.com/docs/getting-started.md)
+- [Refresh Access Token](https://open.longportapp.com/docs/refresh-token-api.md)
+- [Error codes (401003)](https://open.longportapp.com/docs/error-codes.md)
+
+## 1. How each account stores credentials today
+
+Public inventory: [`config/runtime_targets.manifest.json`](../config/runtime_targets.manifest.json).
+
+| Target | GitHub Environment | Cloud Run service | SM token | SM app key | SM app secret |
+| --- | --- | --- | --- | --- | --- |
+| paper | `longbridge-paper` | `longbridge-quant-paper-service` | `longport_token_paper` | `longport-app-key-paper` | `longport-app-secret-paper` |
+| hk | `longbridge-hk` | `longbridge-quant-hk-service` | `longport_token_hk` | `longport-app-key-hk` | `longport-app-secret-hk` |
+| sg | `longbridge-sg` | `longbridge-quant-sg-service` | `longport_token_sg` | `longport-app-key-sg` | `longport-app-secret-sg` |
+
+Runtime wiring (Actions deploy + Cloud Run):
+
+- Env vars `LONGPORT_SECRET_NAME` / `LONGPORT_APP_KEY_SECRET_NAME` / `LONGPORT_APP_SECRET_SECRET_NAME` point at the SM **names** above (per Environment / deploy inputs).
+- **App Key / App Secret** are mounted into the revision as Cloud Run secret env refs (`LONGPORT_APP_KEY` / `LONGPORT_APP_SECRET` → `:latest`).
+- **Access Token** is **not** relied on as a static revision env value for broker auth: bootstrap reads SM `projects/.../secrets/<LONGPORT_SECRET_NAME>/versions/latest` via `quant_platform_kit.longbridge.auth.fetch_token_from_secret` (pinned QPK in `pyproject.toml`).
+- Manual portal-reset write path: [`.github/workflows/rotate-longport-secrets.yml`](../.github/workflows/rotate-longport-secrets.yml) (temporary repo secrets → SM versions). Deploy SA needs `roles/secretmanager.secretVersionAdder` on those secrets (HK was granted separately).
+
+Never log or commit secret **values**; this runbook only names resources.
+
+## 2. Pre-expiry refresh: implemented, but historically ineffective
+
+### What exists
+
+- QPK: `quant_platform_kit.longbridge.auth.refresh_token_if_needed` calls Legacy `GET https://openapi.longportapp.com/v1/token/refresh` with HMAC headers, then writes the new token to SM when `code == 0`.
+- Platform: `TOKEN_REFRESH_THRESHOLD_DAYS = 30` in `main.py`; `LongBridgeRuntimeBootstrap.build_contexts()` invokes refresh before building quote/trade contexts.
+- Read-only paths **intentionally skip** refresh: `build_read_only_contexts`, account-snapshot metadata read, paper command consumer, and HK/SG history probe branch that uses `build_account_snapshot_broker_contexts()`.
+
+### Why tokens still expired
+
+1. **Refresh only rides strategy bootstrap.** When `RUNTIME_TARGET_ENABLED=false` (or strategy cycles are otherwise not running), the refresh path never runs. Daily probe / heartbeat still need a valid token but use read-only context builders.
+2. **Past expiry is terminal for refresh.** Vendor 401003 + docs: refresh must happen **before** expiry; portal reset is the only recovery afterward (matches HK incident).
+3. **Soft-fail hides pre-expiry API errors.** If refresh returns non-zero **and** JWT `exp` is still in the future, QPK returns the old token instead of failing closed—so a broken refresh can sit silent until hard expiry.
+4. **Missing `expired_at` query param.** Vendor API marks `expired_at` required; official SDK `Config.refresh_access_token(expired_at=...)` sends it (default ~90 days). Current QPK call signs/sends **empty** params. That is a likely contributor to silent refresh failure (covered by soft-fail above). Fix belongs in QPK + tests, then platform pin bump.
+5. **IAM for writers.** Runtime/Action writers need SM add-version permission; without it, even a successful LongPort refresh cannot persist (rotate workflow surfaced this for HK).
+
+## 3. OAuth2 availability (path B)
+
+LongPort OpenAPI now documents **OAuth 2.0 as recommended** for new integrations: register client (`/oauth2/register`), browser `authorization_code` + `refresh_token`, SDK `Config.from_oauth` / `OAuthBuilder`, token file under `~/.longport/openapi/tokens/<client_id>`, SDK auto-refresh. Legacy App Key mode remains compatible; Legacy `refresh_access_token` is **not** supported in OAuth mode.
+
+For Cloud Run paper/HK/SG this is **not** a small drop-in:
+
+- Needs interactive (or carefully automated) consent **per account**.
+- Must replace HMAC App Key/Secret signing with Bearer OAuth tokens end-to-end in QPK `build_contexts` and any custom signed HTTP.
+- Must store OAuth refresh material in SM (not home-directory files on ephemeral containers).
+- Platform currently pins `longport==3.0.23`; OAuth-first SDK surface is on newer 4.x lines—bump is a separate risk.
+
+Treat OAuth as a **follow-on migration** after path A is green, not the emergency durability fix.
+
+## 4. Recommended path and blast radius
+
+| Phase | Action | Targets | Blast radius |
+| --- | --- | --- | --- |
+| A0 (this PR) | Runbook + read-only JWT expiry inspector (no refresh, no SM write) | paper / hk / sg | Docs + optional manual inspect only |
+| A1 | QPK: send `expired_at`; fail closed on pre-expiry refresh failure; keep SM write via store_rw | kit first | Shared kit; pin bump in platform after |
+| A2 | Dedicated refresh job (Actions `workflow_dispatch` → then schedule) calling refresh **before** expiry, independent of `RUNTIME_TARGET_ENABLED` | **paper first**, then **sg**, **hk last** | Mutates token SM version; invalidates previous Access Token on success |
+| A3 | Alert when days-to-exp &lt; threshold (reuse inspector) | all | Notify only |
+| B (later) | OAuth spike on paper only, SDK 4.x, SM-backed refresh token | paper → sg → hk | Large: auth model + SDK + deploy |
+
+**HK last** because it was just healed via portal reset + SM rotate + QRS binding; do not experiment with token invalidation there until paper/SG prove A1+A2.
+
+Constraints this plan respects: no `independent_get` / ingress changes, no production strategy enablement flips, no secret values in docs/logs, no strategy logic changes.
+
+## 5. Exact next PR scope (do not fold into this PR)
+
+1. **QuantPlatformKit** – `longbridge/auth.py` + `tests/test_longbridge_auth.py`:
+   - Pass ISO-8601 `expired_at` on `/v1/token/refresh` (and include it in the signed `params` string).
+   - On non-zero refresh while still pre-expiry: raise (or structured error) instead of returning the old token.
+   - Optionally prefer official SDK `Config.refresh_access_token` once pin allows; keep SM persistence in kit.
+2. **LongBridgePlatform** – after QPK pin:
+   - `workflow_dispatch` refresh job per target (reuse rotate’s target matrix / WIF deploy SA); schedule only after paper dry-run succeeds.
+   - Confirm `secretVersionAdder` (or store_rw equivalent) on paper + sg (+ hk when ready).
+   - Keep probe/snapshot read-only (no refresh on those paths).
+3. **Ops** – calendar reminder / alert from expiry inspector until A2 is scheduled.
+4. **Not in next PR:** OAuth client registration, `longport` 4.x bump, enabling `RUNTIME_TARGET_ENABLED`, ingress, or strategy changes.
+
+## Emergency recovery (already proven on HK)
+
+1. Developer Portal: reset Access Token (and confirm App Key/Secret if needed) for that account.
+2. Set temporary repo secrets `ROTATE_LONGPORT_TOKEN` / `ROTATE_LONGPORT_APP_KEY` / `ROTATE_LONGPORT_APP_SECRET`.
+3. Run **Rotate LongPort Secrets** with `target=paper|hk|sg`.
+4. Delete temporary repo secrets.
+5. Re-run heartbeat / probe; if account-history source binding changes, update QRS expected binding (HK required this after rotate).
+
+## Related code pointers
+
+- Platform bootstrap: `application/runtime_bootstrap_adapters.py`
+- Composer read-only vs refresh: `application/runtime_composer.py`
+- Probe history branch (no refresh): `main.py` `run_probe`
+- Rotate workflow: `.github/workflows/rotate-longport-secrets.yml`
+- Read-only expiry inspect: `.github/workflows/inspect-longport-token-expiry.yml` + `scripts/inspect_longport_token_expiry.py`
diff --git a/scripts/inspect_longport_token_expiry.py b/scripts/inspect_longport_token_expiry.py
new file mode 100755
index 0000000..0f264fb
--- /dev/null
+++ b/scripts/inspect_longport_token_expiry.py
@@ -0,0 +1,144 @@
+#!/usr/bin/env python3
+"""Read-only LongPort Access Token expiry inspector.
+
+Decodes JWT ``exp`` from a Secret Manager token secret and prints days remaining.
+Never prints secret values, never calls /v1/token/refresh, never adds SM versions.
+
+Usage (ADC or GHA WIF already authenticated):
+
+  python scripts/inspect_longport_token_expiry.py \\
+    --project longbridgequant \\
+    --secret longport_token_paper \\
+    --warn-days 30
+"""
+
+from __future__ import annotations
+
+import argparse
+import base64
+import json
+import sys
+import time
+from typing import Any
+
+
+TARGET_SECRETS = {
+    "paper": "longport_token_paper",
+    "hk": "longport_token_hk",
+    "sg": "longport_token_sg",
+}
+
+
+def decode_token_expiry_unix(token: str) -> float | None:
+    """Return JWT exp as unix seconds, or None if the token is not a decodable JWT."""
+    try:
+        parts = token.split(".")
+        if len(parts) <= 1:
+            return None
+        payload_b64 = parts[1]
+        padded = payload_b64 + "=" * (-len(payload_b64) % 4)
+        payload = json.loads(base64.urlsafe_b64decode(padded).decode("utf-8"))
+        expiry = payload.get("exp")
+        if expiry is None:
+            return None
+        return float(expiry)
+    except Exception:
+        return None
+
+
+def days_until_expiry(expiry_unix: float, *, now: float | None = None) -> float:
+    current = time.time() if now is None else float(now)
+    return (float(expiry_unix) - current) / 86400.0
+
+
+def access_secret_latest(project_id: str, secret_name: str) -> str:
+    try:
+        import google.cloud.secretmanager_v1 as secret_manager
+    except ImportError:  # pragma: no cover - depends on install layout
+        from google.cloud import secret_manager
+
+    client = secret_manager.SecretManagerServiceClient()
+    name = f"projects/{project_id}/secrets/{secret_name}/versions/latest"
+    response = client.access_secret_version(request={"name": name})
+    return response.payload.data.decode("UTF-8").strip()
+
+
+def inspect_one(
+    *,
+    project_id: str,
+    secret_name: str,
+    warn_days: float,
+    now: float | None = None,
+    token_reader: Any | None = None,
+) -> dict[str, Any]:
+    reader = token_reader or access_secret_latest
+    token = reader(project_id, secret_name)
+    expiry = decode_token_expiry_unix(token)
+    result: dict[str, Any] = {
+        "project_id": project_id,
+        "secret_name": secret_name,
+        "jwt_exp_present": expiry is not None,
+        "warn_days": float(warn_days),
+    }
+    if expiry is None:
+        result["status"] = "undecodable"
+        result["ok"] = False
+        return result
+    remaining = days_until_expiry(expiry, now=now)
+    result["days_until_expiry"] = round(remaining, 3)
+    result["expired"] = remaining <= 0
+    if remaining <= 0:
+        result["status"] = "expired"
+        result["ok"] = False
+    elif remaining < float(warn_days):
+        result["status"] = "warn"
+        result["ok"] = False
+    else:
+        result["status"] = "ok"
+        result["ok"] = True
+    return result
+
+
+def build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--project", required=True, help="GCP project id")
+    parser.add_argument(
+        "--target",
+        choices=sorted(TARGET_SECRETS),
+        help="Named runtime target; sets --secret from the public manifest mapping",
+    )
+    parser.add_argument(
+        "--secret",
+        help="Explicit Secret Manager token secret name (overrides --target)",
+    )
+    parser.add_argument(
+        "--warn-days",
+        type=float,
+        default=30.0,
+        help="Fail (exit 2) when days remaining is below this threshold (default 30)",
+    )
+    return parser
+
+
+def main(argv: list[str] | None = None) -> int:
+    args = build_parser().parse_args(argv)
+    secret_name = args.secret
+    if not secret_name:
+        if not args.target:
+            print("error: provide --target or --secret", file=sys.stderr)
+            return 2
+        secret_name = TARGET_SECRETS[args.target]
+    result = inspect_one(
+        project_id=args.project,
+        secret_name=secret_name,
+        warn_days=args.warn_days,
+    )
+    # Never include token material; result is names + numeric expiry distance only.
+    print(json.dumps(result, sort_keys=True))
+    if result.get("ok"):
+        return 0
+    return 2
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/tests/test_inspect_longport_token_expiry.py b/tests/test_inspect_longport_token_expiry.py
new file mode 100644
index 0000000..3b52afb
--- /dev/null
+++ b/tests/test_inspect_longport_token_expiry.py
@@ -0,0 +1,89 @@
+from __future__ import annotations
+
+import base64
+import json
+import sys
+import time
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+from scripts.inspect_longport_token_expiry import (  # noqa: E402
+    TARGET_SECRETS,
+    days_until_expiry,
+    decode_token_expiry_unix,
+    inspect_one,
+    main,
+)
+
+
+def _jwt_with_exp(exp: int) -> str:
+    payload = base64.urlsafe_b64encode(json.dumps({"exp": exp}).encode("utf-8")).decode("utf-8").rstrip("=")
+    return f"hdr.{payload}.sig"
+
+
+def test_target_secret_names_match_public_manifest():
+    assert TARGET_SECRETS == {
+        "paper": "longport_token_paper",
+        "hk": "longport_token_hk",
+        "sg": "longport_token_sg",
+    }
+
+
+def test_decode_token_expiry_unix_reads_exp():
+    token = _jwt_with_exp(1_700_000_000)
+    assert decode_token_expiry_unix(token) == 1_700_000_000.0
+
+
+def test_decode_token_expiry_unix_returns_none_for_opaque():
+    assert decode_token_expiry_unix("not-a-jwt") is None
+
+
+def test_inspect_one_ok_warn_expired_without_leaking_token():
+    now = time.time()
+    secret_token = _jwt_with_exp(int(now + 60 * 86400))
+    ok = inspect_one(
+        project_id="demo",
+        secret_name="longport_token_paper",
+        warn_days=30,
+        now=now,
+        token_reader=lambda *_a, **_k: secret_token,
+    )
+    assert ok["status"] == "ok"
+    assert ok["ok"] is True
+    dumped = json.dumps(ok)
+    assert secret_token not in dumped
+    assert "hdr." not in dumped
+
+    warn = inspect_one(
+        project_id="demo",
+        secret_name="longport_token_paper",
+        warn_days=30,
+        now=now,
+        token_reader=lambda *_a, **_k: _jwt_with_exp(int(now + 10 * 86400)),
+    )
+    assert warn["status"] == "warn"
+    assert warn["ok"] is False
+
+    expired = inspect_one(
+        project_id="demo",
+        secret_name="longport_token_paper",
+        warn_days=30,
+        now=now,
+        token_reader=lambda *_a, **_k: _jwt_with_exp(int(now - 86400)),
+    )
+    assert expired["status"] == "expired"
+    assert expired["ok"] is False
+
+
+def test_days_until_expiry_math():
+    assert abs(days_until_expiry(100_000.0, now=100_000.0 - 2 * 86400) - 2.0) < 1e-9
+
+
+def test_main_requires_target_or_secret(capsys):
+    code = main(["--project", "demo"])
+    assert code == 2
+    err = capsys.readouterr().err
+    assert "provide --target or --secret" in err