diff --git a/.claude/rules/credential-routing.md b/.claude/rules/credential-routing.md
index fe6678f..09efa23 100644
--- a/.claude/rules/credential-routing.md
+++ b/.claude/rules/credential-routing.md
@@ -56,6 +56,20 @@ stdout unless you pass `--unsafe-stdout` (interactive human sessions only):
 | **Env (exec)** | `warden access <need> --exec -- <cmd>` | value injected into the child process env only |
 | **Wrapping token** | `warden access <need> --wrap` | a single-use, short-TTL OpenBao wrapping token to `bao unwrap` in your own context |
 
+### Agent read-boundary on high-risk lanes (WP-0026 T04)
+
+When `WARDEN_AGENT_ID` is set and the catalog lane is `risk: high`, raw value
+streaming is refused (exit 7). Use `--out` / `--exec` / `--wrap` / `--fingerprint`
+only. OpenBao policy `agent-high-risk-boundary` denies data-read on those paths
+for agent tokens (metadata/capabilities only). See
+`wiki/playbooks/agent-read-boundary.md`.
+
+### EXPOSED taint (WP-0026 T05)
+
+`warden taint <catalog-id>` reports KV v2 `custom_metadata` (`exposed_at`,
+`exposed_version`, …) without reading secret data. Convention:
+`wiki/playbooks/exposed-taint.md`.
+
 ### Other capabilities (reuse-surface)
 
 Non-credential capabilities are usually discovered through **reuse-surface** federation
diff --git a/AGENTS.md b/AGENTS.md
index da2913e..c305dcf 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -148,6 +148,15 @@ Requires the `warden` CLI from `~/ops-warden` (`uv tool install .` or `uv run wa
 - `POST /messages/` to `ops-warden` asking for `ISSUE_CORE_API_KEY`, `OPENROUTER_API_KEY`, etc.
 - Inventing `warden secret`, `warden login`, `warden bao`, `warden tunnel` — they do not exist
 - Pasting secrets into Git, State Hub, workplans, logs, or chat
+- **Reading a secret value onto a captured stdout.** Prefer `bao token capabilities`
+  for verify, and `warden access … --out` / `--exec` / `--wrap` for use (WP-0026).
+
+### Agent read-boundary + EXPOSED taint (WP-0026 T04/T05)
+
+- High-risk lanes (`risk: high` in catalog): with `WARDEN_AGENT_ID` set, raw value
+  streaming is refused. Use sanctioned transports only.
+- `warden taint <id>` reports EXPOSED metadata without reading secret data.
+- Playbooks: `wiki/playbooks/agent-read-boundary.md`, `wiki/playbooks/exposed-taint.md`.
 
 ### Other capabilities (reuse-surface)
 
diff --git a/registry/routing/catalog.yaml b/registry/routing/catalog.yaml
index d6a9520..6adaa55 100644
--- a/registry/routing/catalog.yaml
+++ b/registry/routing/catalog.yaml
@@ -290,6 +290,8 @@ entries:
     canon_ref: net-kingdom/docs/platform-identity-security-architecture.md
     reviewed: "2026-07-02"
     status: active
+    # High-risk: provider API key with spend impact + prompt-adjacent (WP-0026 T04).
+    risk: high
     # Concrete, owner-confirmed lane — railiance-platform CCR-2026-0003 / RAILIANCE-WP-0010
     # (promoted 2026-07-02): policy workload-kv-read-llm-connect-provider-secrets and k8s
     # auth role external-secrets-activity-core applied; ExternalSecret
@@ -321,13 +323,20 @@ entries:
     warden_executes: false
     wiki_ref: wiki/playbooks/railiance-backup-offsite-lane.md#worker-checklist
     canon_ref: railiance-platform/docs/workload-kv-access-lanes.md
-    reviewed: "2026-07-07"
-    status: draft
+    reviewed: "2026-07-16"
+    status: active
+    # High-risk: WebDAV upload token + AGE recovery escrow (WP-0026 T04).
+    risk: high
     # CCR-2026-0004: policy + OIDC role applied; values provisioned 2026-07-07.
-    # Promote to active after positive/negative caller verification.
+    # Capabilities-safe re-verify 2026-07-16 (WP-0026 T07): lane-policy token
+    # capabilities=read on data path; default-policy and agent-high-risk-boundary = deny;
+    # field keys present (NC_WEBDAV_TOKEN, NC_WEBDAV_URL, AGE_PRIVATE_KEY) via metadata
+    # lengths only — no value read. Primary fetch field is NC_WEBDAV_TOKEN (AGE is
+    # recovery escrow; fetch only for restore drills with --field not required —
+    # use bao as caller or extend fetch). EXPOSED taint set on version 2 (T05).
     auth_method: "caller's own OpenBao token (OIDC netkingdom role railiance-backup-workload-kv-read)"
     path_template: "platform/workloads/railiance/backup/offsite-lane"
-    fetch_command: "bao kv get -field=<FIELD> platform/workloads/railiance/backup/offsite-lane"
+    fetch_command: "bao kv get -field=NC_WEBDAV_TOKEN platform/workloads/railiance/backup/offsite-lane"
     exec_capable: true
     lane: secret
     # Mixed lane: NC_WEBDAV_TOKEN rotates (provider re-mint); AGE_PRIVATE_KEY
@@ -344,6 +353,7 @@ entries:
         - "Re-establish AGE_PRIVATE_KEY: generate a new keypair (`age-keygen`), decrypt existing offsite artifacts with the old key and re-encrypt to the new recipient, then `bao kv put ... AGE_PRIVATE_KEY=@file` (mode-0600 file, shred after)."
         - "Because AGE_PRIVATE_KEY is recovery escrow, retain the old key offline until re-encryption of all retained backups is confirmed."
         - "Verify capabilities-safe on the data path (`bao token capabilities`); run a restore drill against a re-encrypted artifact."
+        - "After rotation, clear EXPOSED taint: remove custom_metadata exposed_at/exposed_version (see `warden taint railiance-backup-offsite-lane`)."
 
   - id: forgejo-admin-api-token
     title: Forgejo operator/admin API token (PAT)
@@ -355,7 +365,8 @@ entries:
     canon_ref: railiance-platform/docs/workload-kv-access-lanes.md
     reviewed: "2026-07-13"
     status: active
-    resolvable: true
+    # High-risk: site-admin PAT (WP-0026 T04).
+    risk: high
     # CCR-2026-0006: approved by platform-operator 2026-07-12; policy
     # workload-kv-read-forgejo-admin + OIDC role forgejo-admin-workload-kv-read live on
     # bao.coulomb.social; PAT attended-minted and stored under field API_TOKEN at
diff --git a/src/warden/cli.py b/src/warden/cli.py
index fa2f7ea..6236da1 100644
--- a/src/warden/cli.py
+++ b/src/warden/cli.py
@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 import json
+import os
 from datetime import datetime, timedelta, timezone
 from pathlib import Path
 from typing import Annotated, List, Optional
@@ -630,6 +631,9 @@ def _entry_summary(entry) -> dict:
         "canon_ref": entry.canon_ref,
         "reviewed": entry.reviewed,
         "status": entry.status,
+        # Agent read-boundary (WP-0026 T04) — high-risk lanes deny raw agent data reads.
+        "risk": entry.risk,
+        "high_risk": entry.is_high_risk,
         # Renewal guidance (WP-0026 T06) — advisory, no secret values. `has_rotation`
         # lets a caller gate before asking for the full block via `warden rotate-guide`.
         "has_rotation": entry.has_rotation,
@@ -803,6 +807,63 @@ def route_show(
         )
 
 
+@app.command("taint")
+def taint_show(
+    entry_id: Annotated[str, typer.Argument(help="Catalog entry id (see `warden route list`)")],
+    output_json: Annotated[bool, typer.Option("--json", help="Output JSON")] = False,
+) -> None:
+    """Report whether a lane's OpenBao secret is marked EXPOSED (WP-0026 T05).
+
+    Reads KV v2 *metadata only* (custom_metadata: exposed_at, exposed_version, …).
+    Never reads secret data. Advisory — does not rotate or clear taint.
+    """
+    from warden.taint import TaintError, fetch_taint_status
+
+    catalog = _load_catalog()
+    entry = catalog.get(entry_id)
+    if entry is None:
+        # Drafts are findable by exact id via get even when not listed.
+        err.print(
+            f"[red]Unknown routing id {entry_id!r}.[/red] Try: warden route find {entry_id!r} --all"
+        )
+        raise typer.Exit(1)
+
+    try:
+        status = fetch_taint_status(entry)
+    except TaintError as e:
+        err.print(f"[red]taint status unavailable:[/red] {e}")
+        raise typer.Exit(2)
+
+    if output_json:
+        print(json.dumps(status.to_dict(), indent=2))
+        return
+
+    console.print(f"[bold]Taint status — {entry.title}[/bold]  ([cyan]{entry.id}[/cyan])")
+    console.print(f"  path            : {status.path}")
+    if status.error:
+        console.print(f"  [yellow]query error[/yellow] : {status.error}")
+        console.print(
+            "  [dim]Need caller OpenBao auth with metadata-read on the path "
+            "(agent-high-risk-boundary allows metadata; workload-kv-read allows both).[/dim]"
+        )
+        raise typer.Exit(3)
+    if status.tainted:
+        console.print("  tainted         : [red]yes (EXPOSED)[/red]")
+        console.print(f"  exposed_at      : {status.exposed_at}")
+        console.print(f"  exposed_version : {status.exposed_version}")
+        console.print(f"  exposed_reason  : {status.exposed_reason}")
+        console.print(f"  exposed_ref     : {status.exposed_ref}")
+        console.print(f"  current_version : {status.current_version}")
+        console.print(
+            "\n[yellow]Advisory:[/yellow] rotate/re-establish per "
+            f"`warden rotate-guide {entry.id}` then clear custom_metadata keys "
+            "(exposed_at, exposed_version, …). No auto-rotation (Strand B)."
+        )
+    else:
+        console.print("  tainted         : [green]no[/green]")
+        console.print(f"  current_version : {status.current_version}")
+
+
 @app.command("rotate-guide")
 def rotate_guide(
     entry_id: Annotated[str, typer.Argument(help="Catalog entry id (see `warden route list`)")],
@@ -1059,11 +1120,30 @@ def _access_proxy(
             err.print(f"[red]{e}[/red]")
             raise typer.Exit(2)
 
+    # T04 — agent identity on a high-risk lane: never stream raw secret data.
+    # Agents may use sanctioned transports (--out / --exec / --wrap / --fingerprint).
+    agent_id = os.environ.get("WARDEN_AGENT_ID", "").strip()
+    raw_value_stream = (
+        not is_login and not do_exec and not wrap and not out_path and not fingerprint
+    )
+    if raw_value_stream and entry.is_high_risk and agent_id:
+        err.print(
+            f"[red]Agent read-boundary:[/red] {entry.id!r} is risk=high; "
+            f"agent identity {agent_id!r} must not stream raw secret data.\n"
+            "Use a sanctioned transport (value stays off the session transcript):\n"
+            "  --out FILE     write to a mode-0600 file\n"
+            "  --exec -- CMD  inject into a child process env only\n"
+            "  --wrap         single-use OpenBao wrapping token (unwrap out-of-band)\n"
+            "  --fingerprint  masked presence/length/hash only\n"
+            "OpenBao policy `agent-high-risk-boundary` also denies data-read for agents."
+        )
+        raise typer.Exit(7)
+
     # T02 — the sanctioned fetch transports (file / env / wrapping token) never put a
     # secret value on stdout. Streaming a value to stdout is the documented anti-pattern:
     # allowed only to an interactive terminal, and only with an explicit acknowledgment
     # when stdout is captured/piped (the logged-context disclosure risk).
-    if not is_login and not do_exec and not wrap and not out_path and not fingerprint:
+    if raw_value_stream:
         import sys as _sys
 
         if not _sys.stdout.isatty() and not unsafe_stdout:
diff --git a/src/warden/routing/catalog.py b/src/warden/routing/catalog.py
index fde5313..3589256 100644
--- a/src/warden/routing/catalog.py
+++ b/src/warden/routing/catalog.py
@@ -22,7 +22,7 @@ from typing import List, Optional
 
 import yaml
 
-from warden.routing.models import RotationGuide, RouteEntry
+from warden.routing.models import VALID_RISK, RotationGuide, RouteEntry
 
 # Structured handoff string fields (WP-0014) — templates and pointers only.
 # Every one is scanned for accidental secret material; see _assert_no_secret_material.
@@ -303,6 +303,12 @@ def _parse_entry(raw: dict, index: int) -> RouteEntry:
             f"entry {entry_id!r} has invalid lane {lane!r} (expected one of {_VALID_LANES})"
         )
 
+    risk = str(raw.get("risk", "standard")).strip() or "standard"
+    if risk not in VALID_RISK:
+        raise CatalogError(
+            f"entry {entry_id!r} has invalid risk {risk!r} (expected one of {VALID_RISK})"
+        )
+
     return RouteEntry(
         id=entry_id,
         title=str(raw["title"]),
@@ -326,6 +332,7 @@ def _parse_entry(raw: dict, index: int) -> RouteEntry:
         exec_command=handoff["exec_command"],
         pointer_command=handoff["pointer_command"],
         rotation=_parse_rotation(entry_id, raw.get("rotation")),
+        risk=risk,
     )
 
 
diff --git a/src/warden/routing/models.py b/src/warden/routing/models.py
index f87a8d6..9120f77 100644
--- a/src/warden/routing/models.py
+++ b/src/warden/routing/models.py
@@ -28,6 +28,13 @@ class RotationGuide:
     automatable: bool = False
 
 
+# Risk classes for agent read-boundary (WARDEN-WP-0026 T04).
+# high  — recovery escrow, upload tokens, admin PATs, high-spend provider keys.
+#         Agent identities must not hold raw data-read (metadata/capabilities only).
+# standard — ordinary workload secrets (ESO-fed, non-escrow); normal least-privilege.
+VALID_RISK = ("standard", "high")
+
+
 @dataclass
 class RouteEntry:
     id: str
@@ -69,11 +76,18 @@ class RouteEntry:
     pointer_command: Optional[str] = None    # e.g. "secrets-engine route <id> --json"
     # Rotation / re-establishment guidance (WP-0026 T06) — advisory, no secret values.
     rotation: Optional[RotationGuide] = None
+    # Agent read-boundary risk class (WP-0026 T04). high → agents use wrap/out/exec only.
+    risk: str = "standard"  # "standard" | "high"
 
     @property
     def is_active(self) -> bool:
         return self.status == "active"
 
+    @property
+    def is_high_risk(self) -> bool:
+        """True when this lane is on the agent raw-read deny list (WP-0026 T04)."""
+        return self.risk == "high"
+
     @property
     def has_rotation(self) -> bool:
         """True when this lane carries renewal guidance (WP-0026 T06)."""
diff --git a/src/warden/taint.py b/src/warden/taint.py
new file mode 100644
index 0000000..abd18f7
--- /dev/null
+++ b/src/warden/taint.py
@@ -0,0 +1,149 @@
+"""EXPOSED taint convention for OpenBao KV secrets (WARDEN-WP-0026 T05).
+
+Convention (KV v2 ``custom_metadata`` on the secret, never on secret *data*):
+
+* ``exposed_at`` — ISO-8601 UTC datetime when disclosure was recognized
+* ``exposed_version`` — KV version that was (or may have been) disclosed
+* ``exposed_reason`` — short machine-safe reason slug (optional)
+* ``exposed_ref`` — pointer to a lessons note / CCR / incident doc (optional)
+
+A lane is **tainted** when ``exposed_at`` is set and non-empty. Clearing taint
+(after rotation) is an operator action: remove those keys from custom_metadata.
+ops-warden only *reports* taint — it never auto-rotates (Strand B / WP-0027).
+
+This module only shells out to ``bao kv metadata get`` (or equivalent). It never
+reads secret data values.
+"""
+from __future__ import annotations
+
+import json
+import os
+import subprocess
+from dataclasses import dataclass
+from typing import Any, Optional
+
+from warden.routing.models import RouteEntry
+
+# Canonical custom_metadata keys (WP-0026 T05).
+EXPOSED_AT = "exposed_at"
+EXPOSED_VERSION = "exposed_version"
+EXPOSED_REASON = "exposed_reason"
+EXPOSED_REF = "exposed_ref"
+
+_TAINT_KEYS = (EXPOSED_AT, EXPOSED_VERSION, EXPOSED_REASON, EXPOSED_REF)
+
+
+@dataclass(frozen=True)
+class TaintStatus:
+    """Advisory taint view for a lane — no secret values."""
+
+    lane_id: str
+    path: str
+    tainted: bool
+    exposed_at: Optional[str] = None
+    exposed_version: Optional[str] = None
+    exposed_reason: Optional[str] = None
+    exposed_ref: Optional[str] = None
+    current_version: Optional[int] = None
+    error: Optional[str] = None
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "id": self.lane_id,
+            "path": self.path,
+            "tainted": self.tainted,
+            "exposed_at": self.exposed_at,
+            "exposed_version": self.exposed_version,
+            "exposed_reason": self.exposed_reason,
+            "exposed_ref": self.exposed_ref,
+            "current_version": self.current_version,
+            **({"error": self.error} if self.error else {}),
+        }
+
+
+class TaintError(Exception):
+    """Raised when taint status cannot be determined (auth, path, tool)."""
+
+
+def kv_metadata_path(path_template: str) -> str:
+    """Return the logical KV path suitable for ``bao kv metadata get``.
+
+    Catalog paths are logical (``platform/workloads/...``), not API data paths.
+    """
+    return path_template.strip().strip("/")
+
+
+def parse_custom_metadata(meta: dict[str, Any]) -> TaintStatus:
+    """Build a TaintStatus from a ``bao kv metadata get -format=json`` data blob.
+
+    ``meta`` is the ``data`` object (with ``custom_metadata``, ``current_version``).
+    """
+    custom = meta.get("custom_metadata") or {}
+    if not isinstance(custom, dict):
+        custom = {}
+    exposed_at = (custom.get(EXPOSED_AT) or "").strip() or None
+    return TaintStatus(
+        lane_id="",
+        path="",
+        tainted=bool(exposed_at),
+        exposed_at=exposed_at,
+        exposed_version=(custom.get(EXPOSED_VERSION) or "").strip() or None,
+        exposed_reason=(custom.get(EXPOSED_REASON) or "").strip() or None,
+        exposed_ref=(custom.get(EXPOSED_REF) or "").strip() or None,
+        current_version=meta.get("current_version"),
+    )
+
+
+def fetch_taint_status(entry: RouteEntry, *, bao_bin: str = "bao") -> TaintStatus:
+    """Query OpenBao metadata for a catalog entry (never reads secret data).
+
+    Uses the caller's ``BAO_TOKEN`` / ``VAULT_TOKEN`` / ``~/.vault-token`` — same
+    G1 rule as the access proxy. Requires ``path_template`` on the entry.
+    """
+    if not entry.path_template or "<" in entry.path_template:
+        raise TaintError(
+            f"{entry.id!r} has no concrete path_template — cannot query taint metadata."
+        )
+    path = kv_metadata_path(entry.path_template)
+    try:
+        proc = subprocess.run(
+            [bao_bin, "kv", "metadata", "get", "-format=json", path],
+            capture_output=True,
+            text=True,
+            env=os.environ.copy(),
+            check=False,
+        )
+    except FileNotFoundError as e:
+        raise TaintError(f"{bao_bin!r} not found on PATH") from e
+
+    if proc.returncode != 0:
+        err = (proc.stderr or proc.stdout or "metadata get failed").strip().splitlines()
+        # Never echo tokens if somehow present.
+        safe = " ".join(err[:3])[:300]
+        return TaintStatus(
+            lane_id=entry.id,
+            path=path,
+            tainted=False,
+            error=safe or f"bao exit {proc.returncode}",
+        )
+
+    try:
+        payload = json.loads(proc.stdout)
+    except json.JSONDecodeError as e:
+        raise TaintError(f"invalid JSON from bao metadata get: {e}") from e
+
+    data = payload.get("data") if isinstance(payload, dict) else None
+    if not isinstance(data, dict):
+        raise TaintError("bao metadata response missing data object")
+
+    status = parse_custom_metadata(data)
+    return TaintStatus(
+        lane_id=entry.id,
+        path=path,
+        tainted=status.tainted,
+        exposed_at=status.exposed_at,
+        exposed_version=status.exposed_version,
+        exposed_reason=status.exposed_reason,
+        exposed_ref=status.exposed_ref,
+        current_version=status.current_version,
+    )
diff --git a/tests/test_proxy.py b/tests/test_proxy.py
index 0f7bbcd..be0d190 100644
--- a/tests/test_proxy.py
+++ b/tests/test_proxy.py
@@ -383,3 +383,39 @@ def test_access_fingerprint_masks_and_bypasses_stdout_guard(monkeypatch, tmp_pat
     assert r.exit_code == 0
     assert "top-secret-token-value" not in r.output   # value never shown
     assert "hidden" in r.output and "sha256:" in r.output
+
+
+def test_access_agent_high_risk_raw_stream_refused(tmp_path, monkeypatch):
+    """WP-0026 T04: WARDEN_AGENT_ID + risk=high refuses raw value stream (exit 7)."""
+    _proxy_env(monkeypatch, tmp_path)
+    monkeypatch.setenv("VAULT_TOKEN", "caller-token")
+    monkeypatch.setenv("WARDEN_AGENT_ID", "grok")
+    # Prefer high-risk lane; use --unsafe-stdout so T02 would allow if T04 failed.
+    r = runner.invoke(
+        app,
+        [
+            "access", "railiance-backup-offsite-lane",
+            "--fetch", "--no-policy", "--unsafe-stdout",
+        ],
+    )
+    assert r.exit_code == 7, r.output
+    assert "agent read-boundary" in r.output.lower() or "risk=high" in r.output.lower()
+
+
+def test_access_agent_high_risk_fingerprint_allowed(tmp_path, monkeypatch):
+    """Agents may use --fingerprint on high-risk lanes (no raw value)."""
+    _proxy_env(monkeypatch, tmp_path)
+    monkeypatch.setenv("VAULT_TOKEN", "caller-token")
+    monkeypatch.setenv("WARDEN_AGENT_ID", "grok")
+
+    class _Fake:
+        returncode = 0
+        stdout = "should-not-appear"
+
+    monkeypatch.setattr("warden.proxy.subprocess.run", lambda *a, **k: _Fake())
+    r = runner.invoke(
+        app,
+        ["access", "railiance-backup-offsite-lane", "--fingerprint", "--no-policy"],
+    )
+    assert r.exit_code == 0, r.output
+    assert "should-not-appear" not in r.output
diff --git a/tests/test_routing.py b/tests/test_routing.py
index 76fcc10..a3f7587 100644
--- a/tests/test_routing.py
+++ b/tests/test_routing.py
@@ -531,3 +531,47 @@ def test_rotate_guide_cli_ssh_lane_is_graceful():
     # SSH renewal is re-issuance, not a static rotation — exit 0, not an error.
     result = runner.invoke(app, ["rotate-guide", "ssh-cert-host-access"])
     assert result.exit_code == 0
+
+
+# ---------------------------------------------------------------------------
+# Agent read-boundary + risk class (WARDEN-WP-0026 T04)
+# ---------------------------------------------------------------------------
+
+def test_high_risk_lanes_classified():
+    catalog = load_catalog(_repo_catalog())
+    high = {e.id for e in catalog.entries if e.is_high_risk}
+    assert "railiance-backup-offsite-lane" in high
+    assert "forgejo-admin-api-token" in high
+    assert "openrouter-llm-connect" in high
+    # Ordinary workload secrets stay standard unless reclassified.
+    assert catalog.get("issue-core-ingestion-api-key").is_high_risk is False
+
+
+def test_invalid_risk_rejected(tmp_path):
+    bad = dict(ROUTED_ENTRY, risk="critical")
+    with pytest.raises(CatalogError, match="risk"):
+        load_catalog(_write_catalog(tmp_path, [SSH_ENTRY, bad]))
+
+
+def test_backup_lane_promoted_and_resolvable():
+    """WP-0026 T07 — CCR-2026-0004 lane is active, resolvable, high-risk, has rotation."""
+    catalog = load_catalog(_repo_catalog())
+    e = catalog.get("railiance-backup-offsite-lane")
+    assert e is not None
+    assert e.status == "active"
+    assert e.resolvable is True
+    assert e.is_high_risk is True
+    assert e.has_rotation is True
+    assert e.rotation.method == "re-establish"
+    assert "NC_WEBDAV_TOKEN" in (e.fetch_command or "")
+    assert "<" not in (e.fetch_command or "")
+
+
+def test_route_show_json_includes_risk():
+    result = runner.invoke(app, ["route", "show", "railiance-backup-offsite-lane", "--json"])
+    assert result.exit_code == 0
+    payload = json.loads(result.stdout)
+    assert payload["risk"] == "high"
+    assert payload["high_risk"] is True
+    assert payload["resolvable"] is True
+    assert payload["status"] == "active"
diff --git a/tests/test_taint.py b/tests/test_taint.py
new file mode 100644
index 0000000..362eb79
--- /dev/null
+++ b/tests/test_taint.py
@@ -0,0 +1,70 @@
+"""Tests for EXPOSED taint convention (WARDEN-WP-0026 T05)."""
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+from typer.testing import CliRunner
+
+from warden.cli import app
+from warden.taint import (
+    EXPOSED_AT,
+    TaintStatus,
+    parse_custom_metadata,
+    kv_metadata_path,
+)
+
+runner = CliRunner()
+
+
+def test_parse_custom_metadata_tainted():
+    status = parse_custom_metadata({
+        "custom_metadata": {
+            EXPOSED_AT: "2026-07-16T00:00:00Z",
+            "exposed_version": "2",
+            "exposed_reason": "test",
+            "exposed_ref": "history/x.md",
+        },
+        "current_version": 2,
+    })
+    assert status.tainted is True
+    assert status.exposed_at == "2026-07-16T00:00:00Z"
+    assert status.exposed_version == "2"
+    assert status.current_version == 2
+
+
+def test_parse_custom_metadata_clean():
+    status = parse_custom_metadata({"custom_metadata": None, "current_version": 1})
+    assert status.tainted is False
+    assert status.exposed_at is None
+
+
+def test_parse_empty_exposed_at_not_tainted():
+    status = parse_custom_metadata({"custom_metadata": {EXPOSED_AT: "  "}, "current_version": 1})
+    assert status.tainted is False
+
+
+def test_kv_metadata_path_strips():
+    assert kv_metadata_path("  platform/workloads/x  ") == "platform/workloads/x"
+
+
+def test_taint_status_to_dict():
+    s = TaintStatus(
+        lane_id="x", path="p", tainted=True,
+        exposed_at="t", exposed_version="1", current_version=1,
+    )
+    d = s.to_dict()
+    assert d["tainted"] is True
+    assert d["id"] == "x"
+
+
+def test_taint_cli_unknown_id():
+    result = runner.invoke(app, ["taint", "no-such-lane-xyz"])
+    assert result.exit_code == 1
+
+
+def test_taint_cli_template_lane_errors():
+    """openbao-api-key has <placeholders> — cannot query taint."""
+    result = runner.invoke(app, ["taint", "openbao-api-key", "--json"])
+    assert result.exit_code == 2
diff --git a/wiki/CredentialRouting.md b/wiki/CredentialRouting.md
index dc35d6c..772e69d 100644
--- a/wiki/CredentialRouting.md
+++ b/wiki/CredentialRouting.md
@@ -95,10 +95,14 @@ run the owner's tool as the caller and preserve owner custody.
 | `activity-core-issue-sink` | "activity-core + issue-core own emission — pair `ISSUE_CORE_*` env vars" | See `wiki/playbooks/activity-core-issue-sink.md` |
 | `inter-hub-bootstrap-ssh` | "Inter-Hub bootstrap SSH envelope — attended vs unattended branches" | See `wiki/InterHubBootstrapAccessLane.md` |
 | `issue-core-ingestion-api-key` | "railiance-platform OpenBao KV + ESO deliver `ISSUE_CORE_API_KEY` — here is the path" | ESO consumes in-cluster; `warden access issue-core-ingestion-api-key --fetch ISSUE_CORE_API_KEY` as yourself |
-| `openrouter-llm-connect` | "railiance-platform OpenBao KV + ESO deliver `OPENROUTER_API_KEY` to activity-core" | ESO consumes in-cluster; `warden access openrouter-llm-connect --fetch OPENROUTER_API_KEY` as yourself |
+| `openrouter-llm-connect` | "railiance-platform OpenBao KV + ESO deliver `OPENROUTER_API_KEY` to activity-core" | ESO consumes in-cluster; `warden access openrouter-llm-connect --fetch OPENROUTER_API_KEY` as yourself (`risk: high`) |
 | `reuse-surface-hub-write-token` | "railiance-platform OpenBao KV + ESO deliver `REUSE_SURFACE_TOKEN` to reuse-surface" | ESO consumes in-cluster; `warden access reuse-surface-hub-write-token --fetch` as yourself |
+| `railiance-backup-offsite-lane` | "railiance-platform OpenBao KV for Nextcloud WebDAV + age recovery" | `warden access railiance-backup-offsite-lane --out FILE` (`risk: high`; agents: no raw stream) |
+| `forgejo-admin-api-token` | "railiance-platform OpenBao KV for Forgejo admin PAT" | `warden access forgejo-admin-api-token --out FILE` (`risk: high`) |
 
-Promotion criteria: `wiki/playbooks/catalog-lane-promotion.md`.
+Promotion criteria: `wiki/playbooks/catalog-lane-promotion.md`.  
+High-risk / agent boundary: `wiki/playbooks/agent-read-boundary.md`.  
+EXPOSED taint: `wiki/playbooks/exposed-taint.md` · `warden taint <id>`.
 
 **Draft** (hidden from default lookup until owner path ships — `warden route list --all`):
 
diff --git a/wiki/playbooks/agent-read-boundary.md b/wiki/playbooks/agent-read-boundary.md
new file mode 100644
index 0000000..5795c53
--- /dev/null
+++ b/wiki/playbooks/agent-read-boundary.md
@@ -0,0 +1,77 @@
+# Agent read-boundary on high-risk lanes
+
+Date: 2026-07-16  
+Workplan: WARDEN-WP-0026 T04  
+OpenBao policy: `railiance-platform/openbao/policies/agent-high-risk-boundary.hcl`
+
+Coding agents must not hold **raw data-read** on high-risk secrets. They may
+inspect **capabilities** and **metadata**, and may receive values only through
+sanctioned transports (file / exec env / response-wrapping token) under a human
+operator identity.
+
+---
+
+## Risk classification (catalog `risk:`)
+
+| Class | Criteria | Catalog default |
+| --- | --- | --- |
+| `high` | Recovery escrow (e.g. age private keys), upload tokens to external stores, site-admin PATs, high-spend provider keys | explicit `risk: high` |
+| `standard` | Ordinary workload secrets (ESO-fed API keys without escrow/admin blast radius) | omitted / `standard` |
+
+**Current high-risk lanes (ops-warden catalog):**
+
+| Catalog id | Why high |
+| --- | --- |
+| `railiance-backup-offsite-lane` | Nextcloud upload + `AGE_PRIVATE_KEY` recovery escrow |
+| `forgejo-admin-api-token` | Forgejo site-admin PAT |
+| `openrouter-llm-connect` | Provider key (spend + prompt-adjacent) |
+
+Keep this table in sync with `risk: high` rows in `registry/routing/catalog.yaml`
+and path denials in `agent-high-risk-boundary.hcl`.
+
+---
+
+## OpenBao side
+
+1. **Operator OIDC roles** keep `workload-kv-read-*` for the lane (data `read`).
+2. **Agent identities** attach `agent-high-risk-boundary` (or equivalent) and
+   **must not** also attach the lane's `workload-kv-read-*` policy.
+3. Verify with capabilities only (never `kv get` for deny tests):
+
+```bash
+# Agent-shaped token
+AGENT=$(bao token create -policy=agent-high-risk-boundary -ttl=5m -field=token)
+bao token capabilities "$AGENT" platform/data/workloads/railiance/backup/offsite-lane
+# → deny
+bao token capabilities "$AGENT" platform/metadata/workloads/railiance/backup/offsite-lane
+# → read
+bao token revoke "$AGENT"
+```
+
+Wrapped/proxied access for agents: a human operator (or credential broker with
+response-wrap) fetches under an operator identity and delivers via
+`warden access … --wrap` / `--out` / `--exec`. Agents do not unwrap into chat.
+
+---
+
+## ops-warden side
+
+When `WARDEN_AGENT_ID` is set and the lane is `risk: high`, `warden access --fetch`
+**refuses raw value streaming** (exit 7). Use:
+
+```bash
+export WARDEN_AGENT_ID=grok   # or claude, codex
+warden access railiance-backup-offsite-lane --no-policy --out /tmp/nc.token
+warden access railiance-backup-offsite-lane --no-policy --wrap
+warden access railiance-backup-offsite-lane --no-policy --fingerprint
+```
+
+`warden route show <id> --json` includes `"risk"` and `"high_risk"`.
+
+---
+
+## See also
+
+- `.claude/rules/credential-routing.md` — safe transports
+- `wiki/playbooks/exposed-taint.md` — EXPOSED metadata convention
+- `history/2026-07-16-credential-disclosure-lessons.md`
diff --git a/wiki/playbooks/catalog-lane-promotion.md b/wiki/playbooks/catalog-lane-promotion.md
index 4e71d3f..e1352fd 100644
--- a/wiki/playbooks/catalog-lane-promotion.md
+++ b/wiki/playbooks/catalog-lane-promotion.md
@@ -87,13 +87,17 @@ out on the OpenBao-delivered value, positive + negative verification audit-logge
 
 ---
 
-## Draft lanes (2026-07-02)
+## Draft lanes (2026-07-16)
 
 | Catalog `id` | Blocker |
 | --- | --- |
 | `object-storage-sts` | NK-WP-0007 vending path not production-exercised |
 | `database-dynamic-credentials` | OpenBao database engine role paths TBD per workload |
 
+**Promoted 2026-07-16:** `railiance-backup-offsite-lane` — CCR-2026-0004
+capabilities-safe re-verify (WP-0026 T07); primary field `NC_WEBDAV_TOKEN`;
+`risk: high` + EXPOSED taint on version 2 (operator may rotate optionally).
+
 Re-run promotion when the owning repo closes the blocker; do not promote on
 playbook prose alone.
 
diff --git a/wiki/playbooks/exposed-taint.md b/wiki/playbooks/exposed-taint.md
new file mode 100644
index 0000000..4875d22
--- /dev/null
+++ b/wiki/playbooks/exposed-taint.md
@@ -0,0 +1,71 @@
+# EXPOSED taint convention (OpenBao KV v2)
+
+Date: 2026-07-16  
+Workplan: WARDEN-WP-0026 T05
+
+Mark a secret as **EXPOSED** when it may have landed in a logged or shared context
+(agent transcript, chat, CI log). Taint is **advisory**: it does not revoke access
+or rotate values. Strand B (`WARDEN-WP-0027`) may later drive rotation of tainted
+lanes; Strand A only records and reports.
+
+---
+
+## Custom metadata keys
+
+Set on the KV v2 secret **metadata** (never in secret data values):
+
+| Key | Required | Meaning |
+| --- | --- | --- |
+| `exposed_at` | yes | ISO-8601 UTC when disclosure was recognized |
+| `exposed_version` | recommended | KV version that was (or may have been) disclosed |
+| `exposed_reason` | optional | short slug, e.g. `agent-session-kv-get-disclosure` |
+| `exposed_ref` | optional | pointer to lessons note / CCR / incident doc |
+
+A lane is **tainted** when `exposed_at` is present and non-empty.
+
+---
+
+## Mark EXPOSED
+
+```bash
+bao kv metadata put \
+  -custom-metadata=exposed_at=2026-07-16T00:00:00Z \
+  -custom-metadata=exposed_version=2 \
+  -custom-metadata=exposed_reason=agent-session-kv-get-disclosure \
+  -custom-metadata=exposed_ref=history/2026-07-16-credential-disclosure-lessons.md \
+  platform/workloads/railiance/backup/offsite-lane
+```
+
+## Report taint (no secret values)
+
+```bash
+warden taint railiance-backup-offsite-lane
+warden taint railiance-backup-offsite-lane --json
+# or:
+bao kv metadata get platform/workloads/railiance/backup/offsite-lane
+```
+
+## Clear taint (after rotation)
+
+After following `warden rotate-guide <id>` and verifying the new version:
+
+```bash
+# Rewrite metadata without the exposed_* keys (preserve any other custom_metadata).
+bao kv metadata put platform/workloads/<lane-path>
+# Or put only non-taint keys you still need.
+warden taint <id>   # expect tainted: no
+```
+
+---
+
+## Semi-automatic candidates
+
+Reads of high-risk paths from agent/shared identities in the OpenBao audit log
+are candidates for marking EXPOSED. Marking remains an operator decision; do not
+auto-taint from noisy audit alone without human review.
+
+## See also
+
+- `history/2026-07-16-credential-disclosure-lessons.md`
+- `wiki/playbooks/catalog-lane-promotion.md` (capabilities-safe verify)
+- OpenBao policy `agent-high-risk-boundary` (WP-0026 T04)
diff --git a/wiki/playbooks/railiance-backup-offsite-lane.md b/wiki/playbooks/railiance-backup-offsite-lane.md
index d000b82..5bde5ee 100644
--- a/wiki/playbooks/railiance-backup-offsite-lane.md
+++ b/wiki/playbooks/railiance-backup-offsite-lane.md
@@ -1,7 +1,7 @@
 # Railiance Offsite Backup Lane
 
-Date: 2026-07-07  
-Catalog: `railiance-backup-offsite-lane` (status `draft`, `resolvable: false` until verified)  
+Date: 2026-07-16  
+Catalog: `railiance-backup-offsite-lane` (status `active`, `resolvable: true`, `risk: high`)  
 Owner: `railiance-platform` (CCR-2026-0004)
 
 Nextcloud WebDAV upload token and URL for age-encrypted offsite backups (Option A).
@@ -15,9 +15,11 @@ Used by `railiance-backup` (workstation) and `forgejo-backup` (platform).
 | --- | --- |
 | Mount | `platform` |
 | Path | `platform/workloads/railiance/backup/offsite-lane` |
-| Fields | `NC_WEBDAV_TOKEN`, `NC_WEBDAV_URL`, `AGE_PRIVATE_KEY` |
-| Policy | `workload-kv-read-railiance-backup-offsite-lane` |
+| Fields | `NC_WEBDAV_TOKEN` (primary fetch), `NC_WEBDAV_URL`, `AGE_PRIVATE_KEY` (recovery escrow) |
+| Policy | `workload-kv-read-railiance-backup-offsite-lane` (operator OIDC) |
+| Agent policy | `agent-high-risk-boundary` — **deny** data-read; metadata only |
 | OIDC role | `railiance-backup-workload-kv-read` (`groups=net-kingdom-admins`) |
+| Risk | `high` (upload token + age recovery escrow) |
 
 ---
 
@@ -29,7 +31,16 @@ Used by `railiance-backup` (workstation) and `forgejo-backup` (platform).
    bao login -method=oidc -path=netkingdom role=railiance-backup-workload-kv-read
    ```
 
-2. **Export for a backup run** (value streams to your shell — never paste into chat):
+2. **Export for a backup run** (sanctioned transports — never paste into chat):
+
+   ```bash
+   # Preferred: file or exec injection via warden
+   warden access railiance-backup-offsite-lane --no-policy --out /tmp/nc.token
+   # or:
+   warden access railiance-backup-offsite-lane --no-policy --exec -- env | grep -v .
+   ```
+
+   If you must use raw bao in an interactive human shell (not an agent session):
 
    ```bash
    export RAILIANCE_BACKUP_NC_TOKEN=$(
@@ -40,10 +51,11 @@ Used by `railiance-backup` (workstation) and `forgejo-backup` (platform).
    )
    ```
 
-3. **Or proxy via warden access** (after catalog promotion):
+3. **Proxy via warden access** (catalog active + resolvable):
 
    ```bash
-   warden access railiance-backup-offsite-lane --no-policy --fetch --field NC_WEBDAV_TOKEN
+   warden access railiance-backup-offsite-lane --no-policy --fetch --out /tmp/nc.token
+   # Primary field is NC_WEBDAV_TOKEN. AGE_PRIVATE_KEY is recovery escrow only.
    ```
 
 4. **Run backup**:
@@ -57,6 +69,8 @@ Used by `railiance-backup` (workstation) and `forgejo-backup` (platform).
    ```
 
 `AGE_PRIVATE_KEY` in the same path is recovery escrow — fetch only for restore drills.
+**Agents** (`WARDEN_AGENT_ID` set) cannot stream raw high-risk values; use `--out` /
+`--exec` / `--wrap`. See `wiki/playbooks/agent-read-boundary.md`.
 
 ---
 
@@ -67,17 +81,51 @@ value to "confirm" it triggered the 2026-07-16 disclosure of `NC_WEBDAV_TOKEN` /
 `NC_WEBDAV_URL` / `AGE_PRIVATE_KEY` (see `history/2026-07-16-credential-disclosure-lessons.md`).
 
 ```bash
-# Positive: lane OIDC identity can read the data path
-bao login -method=oidc -path=netkingdom role=railiance-backup-workload-kv-read
-bao token capabilities "$(bao print token)" platform/data/workloads/railiance/backup/offsite-lane
+# Positive: lane policy identity can read the data path
+LANE=$(bao token create -policy=workload-kv-read-railiance-backup-offsite-lane -ttl=2m -field=token)
+bao token capabilities "$LANE" platform/data/workloads/railiance/backup/offsite-lane
 #   → expect: read
+bao token revoke "$LANE"
 
 # Negative: default-only identity is denied (no value is read)
 DEFAULT_TOKEN=$(bao token create -policy=default -field=token)   # if this is denied, that IS the pass — do NOT fall back
 bao token capabilities "$DEFAULT_TOKEN" platform/data/workloads/railiance/backup/offsite-lane
 #   → expect: deny
+bao token revoke "$DEFAULT_TOKEN"
+
+# Agent boundary: data deny, metadata allow
+AGENT=$(bao token create -policy=agent-high-risk-boundary -ttl=2m -field=token)
+bao token capabilities "$AGENT" platform/data/workloads/railiance/backup/offsite-lane   # deny
+bao token capabilities "$AGENT" platform/metadata/workloads/railiance/backup/offsite-lane # read
+bao token revoke "$AGENT"
 ```
 
 The capability lists contain no secret material — safe to record on
 `CCR-2026-0004` as promotion evidence. Full pattern:
-`wiki/playbooks/catalog-lane-promotion.md#capabilities-safe-lane-verification`.
\ No newline at end of file
+`wiki/playbooks/catalog-lane-promotion.md#capabilities-safe-lane-verification`.
+
+### Evidence recorded 2026-07-16 (WP-0026 T07)
+
+| Check | Result |
+| --- | --- |
+| Policy `workload-kv-read-railiance-backup-offsite-lane` present | pass |
+| OIDC role `railiance-backup-workload-kv-read` bound to `net-kingdom-admins` + lane policy | pass |
+| Lane-policy token capabilities on data path | `read` |
+| Default-policy token capabilities on data path | `deny` |
+| Agent-boundary token on data / metadata | `deny` / `read` |
+| Field presence (keys only, lengths; no values) | `NC_WEBDAV_TOKEN`, `NC_WEBDAV_URL`, `AGE_PRIVATE_KEY` present |
+| EXPOSED taint on version 2 | set (see `warden taint railiance-backup-offsite-lane`) |
+| Rotation guidance | `warden rotate-guide railiance-backup-offsite-lane` |
+
+---
+
+## Taint / rotation
+
+```bash
+warden taint railiance-backup-offsite-lane
+warden rotate-guide railiance-backup-offsite-lane
+```
+
+Rotation of exposed values is the **operator's optional call** (buildup mode);
+promotion is not blocked on rotation. After rotation, clear `exposed_*`
+custom_metadata keys (`wiki/playbooks/exposed-taint.md`).
diff --git a/workplans/WARDEN-WP-0026-credential-disclosure-hygiene.md b/workplans/WARDEN-WP-0026-credential-disclosure-hygiene.md
index f82db7f..c0bd296 100644
--- a/workplans/WARDEN-WP-0026-credential-disclosure-hygiene.md
+++ b/workplans/WARDEN-WP-0026-credential-disclosure-hygiene.md
@@ -4,7 +4,7 @@ type: workplan
 title: "Credential disclosure hygiene + rotation guidance (Strand A)"
 domain: infotech
 repo: ops-warden
-status: active
+status: finished
 owner: codex
 topic_slug: custodian
 planning_priority: high
@@ -140,11 +140,21 @@ limitation documented.
 
 ```task
 id: WARDEN-WP-0026-T04
-status: todo
+status: done
 priority: high
 state_hub_task_id: "f95d4381-f995-4c9d-b438-70b4f0ed90c5"
 ```
 
+Done 2026-07-16: Catalog `risk: high|standard` (default standard). High-risk:
+`railiance-backup-offsite-lane`, `forgejo-admin-api-token`, `openrouter-llm-connect`.
+OpenBao policy `agent-high-risk-boundary` (railiance-platform + live write) grants
+metadata/capabilities only and **denies** data-read on those paths — verified with
+minted agent token (data=deny, metadata=read). `warden access` with
+`WARDEN_AGENT_ID` set refuses raw value stream on high-risk lanes (exit 7);
+`--out`/`--exec`/`--wrap`/`--fingerprint` remain. Playbook:
+`wiki/playbooks/agent-read-boundary.md`. Tests in `tests/test_routing.py` +
+`tests/test_proxy.py`.
+
 **Repo: railiance-platform (OpenBao policy/roles).** Agent identities receive
 `capabilities`/metadata and wrapping tokens on high-risk lanes, not raw data
 reads. Align with the existing credential-routing rule ("ops-warden proxies reads
@@ -158,11 +168,19 @@ while still allowing wrapped/proxied access, verified via capabilities checks.
 
 ```task
 id: WARDEN-WP-0026-T05
-status: todo
+status: done
 priority: medium
 state_hub_task_id: "e989f8f0-930e-4d2f-9037-221e04f34199"
 ```
 
+Done 2026-07-16: Convention documented in `wiki/playbooks/exposed-taint.md`
+(`exposed_at`, `exposed_version`, `exposed_reason`, `exposed_ref` on KV v2
+custom_metadata). First worked mark applied to
+`platform/workloads/railiance/backup/offsite-lane` version 2 (disclosure
+incident). `warden taint <id>` (+ `--json`) reports taint via metadata-only
+`bao kv metadata get` — never secret data (`src/warden/taint.py`). Tests in
+`tests/test_taint.py`.
+
 **Repo: railiance-platform (OpenBao) + ops-warden surface.** Establish a KV v2
 `custom_metadata` convention to mark a tainted secret: `exposed_at=<datetime>`
 and the affected `version`. Identify semi-automatic candidates from the OpenBao
@@ -208,17 +226,19 @@ every active lane, and the scorecard fails if any active lane lacks guidance.
 
 ```task
 id: WARDEN-WP-0026-T07
-status: progress
+status: done
 priority: medium
 state_hub_task_id: "9944f46d-3706-43a4-9300-7f63bf87c9ff"
 ```
 
-Lessons-learned note written 2026-07-16:
-`history/2026-07-16-credential-disclosure-lessons.md` (buildup context, exposure
-accepted, three root causes). Remaining: capabilities-based live re-verify of
-CCR-2026-0004 on `bao.coulomb.social` (uses T01 pattern) and its `rotation:` block
-(depends on T06 registry) so the lane can promote to `resolvable: true` and unblock
-RAILIANCE-WP-0015.
+Done 2026-07-16: Lessons note present. Capabilities-safe live re-verify on
+`bao.coulomb.social`: lane-policy token → `read` on data path; default + agent
+boundary → `deny`; field keys present (no values printed). Catalog promoted
+`draft`→`active`, `fetch_command` pinned to `NC_WEBDAV_TOKEN` (no placeholders)
+so `resolvable: true`; `risk: high`; rotation guidance + EXPOSED taint on v2.
+CCR-2026-0004 evidence + `access_frontdoor.resolvable: true` / `readiness: ready`.
+Playbook + `wiki/CredentialRouting.md` updated. Operator may still rotate the
+exposed values optionally (buildup) — not a promotion blocker.
 
 Write a short lessons-learned note (buildup context; exposure accepted; the three
 root causes). Apply T01 + T06 to `CCR-2026-0004` as the first worked lane: