feat(webui): console authorization, RBAC, redaction, and audit model (Closes #633)

Phase 1 of the MCP Control Plane Web Console (#631) defines the model that
future gated writes must pass through, and enables none of them.

The read-only MVP (#426-#436) ships with no authentication; protection comes
from network placement alone (#435). That is adequate while every route is a
GET and inadequate the moment Phase 2 wires a write. This lands the authority
first, so no write can later be added without something to check it against.

webui/console_authz.py
  Identity sources (none / local-dev / access-proxy), a four-role matrix
  (viewer, operator, controller, admin), the privileged-action list, and a
  fail-closed authorize(). Every action maps to a task_key in
  task_capability_map, so the console cannot invent an authority the MCP layer
  does not already define. Roles are always server-side configuration, never a
  client assertion. Deny reasons are closed and enumerated; there is no
  implicit allow branch, and even an allow reports execution_enabled=false
  while ACTIVE_PHASE is 1.

webui/console_redaction.py
  One redaction pass for API payloads, rendered HTML, logs, and audit records.
  Reuses gitea_audit.redact as the shared authority rather than forking it,
  then adds console patterns for keychain references, credential assignments,
  PEM private-key blocks, and JWTs. Never raises: an unredactable value
  degrades to the placeholder rather than being emitted raw.

webui/console_audit.py
  Console-side audit records, which gitea_audit cannot supply: it records MCP
  mutations and carries no console actor, identity source, correlation id, or
  retention class, and an authorization denial is not a mutation at all. The
  two are additive and join on correlation.request_id. Records are redacted at
  build time, re-scanned at write time, and dropped rather than persisted if
  they still trip a detector. Retention is per-record; an unknown action is
  retained as privileged rather than standard.

webui/app.py
  Attaches an authorization block to the existing preview and attempt routes
  and records the decision. The terminal outcome is unchanged - gated_actions
  still fails closed for every action - so this cannot loosen anything. Adds
  GET /api/console/security-model publishing the three policies as JSON.

Probe authentication is deliberately declarative in this slice:
probe_auth_required() reports operator intent and no route consults it. The
documentation says so plainly and a regression test pins the not-enforced
status, so wiring it in Phase 2 is a deliberate change rather than a silent
one. An operator who sets the variable believing it protects a probe would be
worse off than one who knows it does not.

Tests: tests/test_webui_console_authz_audit.py - 75 passed, 93 subtests,
covering each acceptance criterion and each test the issue requires
(redaction units, default-deny for unauthenticated write stubs, audit record
creation for a simulated privileged preview).

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

webui/console_audit.py

@@ -0,0 +1,281 @@
+"""Console audit event schema, retention, and append-only sink (#633).
+
+``gitea_audit`` records MCP-side *mutations*: which profile and Gitea user
+performed which tool call. It carries no console actor, no identity source, no
+correlation identifier, and no retention class, so it cannot answer the
+question #633 exists to answer — *who sat at the console, what did they
+attempt, and was it authorized?* An authorization denial is not a mutation and
+would never appear there at all.
+
+This module adds the console-side record. It does not replace ``gitea_audit``:
+when a Phase 2 action eventually reaches MCP, both fire, correlated by
+``correlation.request_id``.
+
+Design constraints:
+
+- **Redact before persist.** Every record passes through
+  ``webui.console_redaction.redact_payload`` before serialization, so an
+  unredacted field is never durable.
+- **Append-only.** Records are appended as JSON lines. Nothing here updates or
+  deletes; retention is metadata on each record, enforced by an operator-run
+  policy, never by silent rewriting.
+- **Never raises.** Auditing must not break the request it describes. A failed
+  write returns ``False``.
+- **Off by default.** With ``WEBUI_CONSOLE_AUDIT_LOG`` unset, events are still
+  *built* (so callers and tests see the schema) but nothing is written.
+
+A record looks like this (synthetic values):
+
+    {"schema_version": 1, "event_id": "evt-0001",
+     "timestamp": "2026-07-22T10:16:42+00:00",
+     "actor": {"subject": "[email protected]", "role": "operator",
+               "identity_source": "access_proxy", "authenticated": true},
+     "action": "merge_pr", "action_class": "privileged",
+     "target": {"kind": "pr", "ref": "#123"},
+     "result": "denied", "reason_code": "insufficient_role",
+     "correlation": {"request_id": "req-abc", "session_id": null,
+                     "mcp_task": "merge_pr", "mcp_permission": "gitea.pr.merge"},
+     "retention": {"class": "privileged", "days": 365,
+                   "expires_at": "2027-07-22T10:16:42+00:00"},
+     "redacted": true}
+
+Timestamps are timezone-aware ISO-8601 in UTC.
+"""
+
+from __future__ import annotations
+
+import datetime
+import json
+import os
+import uuid
+from typing import Any
+
+from webui import console_authz
+from webui.console_redaction import redact_payload, scan_for_secrets
+
+SCHEMA_VERSION = 1
+
+AUDIT_LOG_ENV = "WEBUI_CONSOLE_AUDIT_LOG"
+
+# Result vocabulary. ``denied`` is the one ``gitea_audit`` has no equivalent
+# for: an authorization refusal never reaches the MCP layer.
+RESULT_ALLOWED = "allowed"
+RESULT_DENIED = "denied"
+RESULT_PREVIEWED = "previewed"
+RESULT_FAILED = "failed"
+RESULT_SUCCEEDED = "succeeded"
+
+RESULTS = frozenset(
+    {
+        RESULT_ALLOWED,
+        RESULT_DENIED,
+        RESULT_PREVIEWED,
+        RESULT_FAILED,
+        RESULT_SUCCEEDED,
+    }
+)
+
+# Retention classes and default lifetimes in days. Privileged and break-glass
+# records outlive routine ones because they are what an incident review needs.
+RETENTION_STANDARD = "standard"
+RETENTION_PRIVILEGED = "privileged"
+RETENTION_BREAK_GLASS = "break_glass"
+
+RETENTION_DAYS: dict[str, int] = {
+    RETENTION_STANDARD: 90,
+    RETENTION_PRIVILEGED: 365,
+    RETENTION_BREAK_GLASS: 730,
+}
+
+# Fields every record must carry. Asserted by the test suite so a future edit
+# cannot quietly drop one.
+REQUIRED_FIELDS: tuple[str, ...] = (
+    "schema_version",
+    "event_id",
+    "timestamp",
+    "actor",
+    "action",
+    "action_class",
+    "target",
+    "result",
+    "reason_code",
+    "correlation",
+    "retention",
+    "redacted",
+)
+
+REQUIRED_ACTOR_FIELDS: tuple[str, ...] = (
+    "subject",
+    "role",
+    "identity_source",
+    "authenticated",
+)
+
+REQUIRED_CORRELATION_FIELDS: tuple[str, ...] = (
+    "request_id",
+    "session_id",
+    "mcp_task",
+    "mcp_permission",
+)
+
+
+def audit_log_path() -> str | None:
+    """Configured sink path, or ``None`` when console auditing is off."""
+    return (os.environ.get(AUDIT_LOG_ENV) or "").strip() or None
+
+
+def audit_enabled() -> bool:
+    return audit_log_path() is not None
+
+
+def retention_class_for(action: console_authz.ConsoleAction | None) -> str:
+    """Classify retention from the action, defaulting to the longest-lived.
+
+    An unknown action is treated as privileged rather than standard: for a
+    safety control the conservative direction is to keep the record longer.
+    """
+    if action is None:
+        return RETENTION_PRIVILEGED
+    if action.break_glass:
+        return RETENTION_BREAK_GLASS
+    if action.privileged:
+        return RETENTION_PRIVILEGED
+    return RETENTION_STANDARD
+
+
+def _retention_block(
+    retention_class: str, now: datetime.datetime
+) -> dict[str, Any]:
+    days = RETENTION_DAYS.get(
+        retention_class, RETENTION_DAYS[RETENTION_PRIVILEGED]
+    )
+    return {
+        "class": retention_class,
+        "days": days,
+        "expires_at": (now + datetime.timedelta(days=days)).isoformat(),
+    }
+
+
+def build_event(
+    *,
+    action_id: str,
+    result: str,
+    decision: console_authz.AuthorizationDecision | None = None,
+    principal: console_authz.Principal | None = None,
+    target: dict[str, Any] | None = None,
+    reason_code: str | None = None,
+    request_id: str | None = None,
+    session_id: str | None = None,
+    detail: str | None = None,
+    metadata: dict[str, Any] | None = None,
+    now: datetime.datetime | None = None,
+    event_id: str | None = None,
+) -> dict[str, Any]:
+    """Build one redacted, JSON-able console audit record.
+
+    Redaction runs here rather than at write time so an in-memory record handed
+    to a template or an API response is already clean.
+    """
+    ts = now or datetime.datetime.now(datetime.timezone.utc)
+    action = console_authz.get_action(action_id)
+    who = principal or (
+        decision.principal if decision else console_authz.ANONYMOUS
+    )
+    resolved_result = result if result in RESULTS else RESULT_FAILED
+    resolved_reason = reason_code or (
+        decision.reason_code if decision else "unspecified"
+    )
+    retention_class = retention_class_for(action)
+
+    event: dict[str, Any] = {
+        "schema_version": SCHEMA_VERSION,
+        "event_id": event_id or f"evt-{uuid.uuid4().hex}",
+        "timestamp": ts.isoformat(),
+        "actor": who.to_dict(),
+        "action": action_id,
+        "action_class": action.action_class if action else "unknown",
+        "target": dict(target or {}),
+        "result": resolved_result,
+        "reason_code": resolved_reason,
+        "correlation": {
+            "request_id": request_id,
+            "session_id": session_id,
+            "mcp_task": action.task_key if action else None,
+            "mcp_permission": action.mcp_permission if action else None,
+        },
+        "retention": _retention_block(retention_class, ts),
+        "redacted": True,
+        "detail": detail,
+        "metadata": dict(metadata or {}),
+    }
+    if decision is not None:
+        # Deliberately *not* named "authorization": ``gitea_audit`` treats that
+        # substring as a secret key hint (it matches the HTTP Authorization
+        # header) and would replace this whole block with the placeholder.
+        event["decision"] = {
+            "allowed": decision.allowed,
+            "required_role": decision.required_role,
+            "requires_confirmation": decision.requires_confirmation,
+            "dual_control": decision.dual_control,
+            "break_glass": decision.break_glass,
+            "execution_enabled": decision.execution_enabled,
+        }
+
+    redacted = redact_payload(event)
+    if not isinstance(redacted, dict):  # pragma: no cover - defensive
+        return {"schema_version": SCHEMA_VERSION, "redacted": True}
+    return redacted
+
+
+def write_event(event: dict[str, Any], path: str | None = None) -> bool:
+    """Append *event* as one JSON line. Never raises.
+
+    Returns ``True`` when a line was written, ``False`` when auditing is off or
+    the write failed. A record that still trips a secret detector is dropped
+    rather than persisted.
+    """
+    sink = path or audit_log_path()
+    if not sink:
+        return False
+    try:
+        if scan_for_secrets(event):
+            return False
+        line = json.dumps(event, default=str, sort_keys=True)
+        with open(sink, "a", encoding="utf-8") as handle:
+            handle.write(line + "\n")
+        return True
+    except Exception:
+        return False
+
+
+def record_event(**kwargs: Any) -> dict[str, Any]:
+    """Build and persist one record; return the record either way.
+
+    Callers get the record back so it can be surfaced in a response or a test
+    regardless of whether a sink is configured.
+    """
+    event = build_event(**kwargs)
+    written = write_event(event)
+    return {"event": event, "written": written}
+
+
+def audit_policy() -> dict[str, Any]:
+    """Machine-readable audit schema and retention defaults (never secrets)."""
+    return {
+        "schema_version": SCHEMA_VERSION,
+        "required_fields": list(REQUIRED_FIELDS),
+        "required_actor_fields": list(REQUIRED_ACTOR_FIELDS),
+        "required_correlation_fields": list(REQUIRED_CORRELATION_FIELDS),
+        "results": sorted(RESULTS),
+        "retention_defaults_days": dict(RETENTION_DAYS),
+        "sink_env": AUDIT_LOG_ENV,
+        "enabled": audit_enabled(),
+        "append_only": True,
+        "redact_before_persist": True,
+        "timestamp_format": "ISO-8601, timezone-aware, UTC",
+        "relationship_to_mcp_audit": (
+            "webui.console_audit records console intent and authorization "
+            "outcomes; gitea_audit records MCP mutations. A Phase 2 action "
+            "emits both, correlated by correlation.request_id."
+        ),
+    }