docs(spire): revocation cascade timing + Keylime SPIRE server config

Document the trust withdrawal cascade:
  Keylime breach → posture degraded → sessions downgraded
  → SPIRE re-attestation fails → SVIDs expire
  → service mTLS fails → quorum degrades

No new code for the cascade — it's emergent from existing
re-attestation behavior + the Keylime attestor plugin.
SPIRE federation handles cross-edge propagation through
standard certificate expiration.

Three timing profiles: Standard (~1hr), Enhanced (~15min),
Critical (~5min) with SVID TTL configuration guidance.

Example SPIRE server config with Keylime attestor + k8s_psat
fallback for nodes without hardware TPM.

Signed-off-by: Tyler King <tking@guildhouse.dev>
Signed-off-by: Tyler J King <tking727@gmail.com>

deploy/cascade-timing.md

@@ -0,0 +1,63 @@
+# Revocation Cascade Timing
+
+When Keylime detects a TPM attestation failure, trust withdrawal cascades
+through the stack automatically. No custom revocation protocol — each
+layer reacts to the posture change produced by the layer above it.
+
+## Cascade Stages
+
+| # | Stage | Default Interval | Trigger |
+|---|-------|-----------------|---------|
+| 1 | Keylime detects failure | 300s (pull) / varies (push) | TPM quote mismatch, IMA violation, boot integrity |
+| 2 | Posture evaluator updates ConfigMap | 300s | Keylime verdict changes |
+| 3 | Bascule session downgrade | 30s | posture-current ConfigMap poll |
+| 4 | SPIRE re-attestation fails | varies | Keylime attestor reads ConfigMap |
+| 5 | SVID expiry (identity loss) | 3600s (1 hour) | SPIRE agent can't renew |
+| 6 | Service mTLS failures | immediate after 5 | Peer cert expired/missing |
+| 7 | Quorum degradation | immediate after 6 | SPIRE federation — other members see expired SVIDs |
+
+## Timing Profiles
+
+### Standard (default) — ~1 hour total cascade
+
+Acceptable for most workloads. SVID TTL provides grace period for
+transient failures.
+
+### Enhanced — ~15 minute total cascade
+
+```yaml
+# SVID TTL
+default_x509_svid_ttl: 15m
+# SPIRE re-attestation (implicit via SVID rotation interval)
+# Keylime poll: default 300s is fine
+```
+
+Higher renewal overhead, faster trust withdrawal.
+
+### Critical — ~5 minute total cascade
+
+```yaml
+default_x509_svid_ttl: 5m
+```
+
+Significant renewal overhead. Use only for high-security workloads
+where fast trust withdrawal justifies the cost.
+
+## Cross-Edge (Quorum) Propagation
+
+When one quorum member's edge fails Keylime attestation:
+
+1. That edge's SPIRE server stops issuing SVIDs (Keylime attestor rejects)
+2. Existing SVIDs expire (per TTL)
+3. Other members' services see TLS handshake failures (expired peer cert)
+4. No explicit cross-member notification needed — SPIRE federation's
+   standard certificate lifecycle handles it
+
+This is automatic. SPIRE federation trusts Member A's SVIDs via the
+bundle exchange. When those SVIDs expire and aren't renewed, Member B's
+services can't verify them.
+
+## Configuration
+
+See `spire-server-keylime.yaml` for the SPIRE server configuration with
+the Keylime node attestor plugin and timing parameters.

deploy/spire-server-keylime.yaml

@@ -0,0 +1,72 @@
+# SPIRE Server configuration with Keylime node attestor.
+#
+# Replaces tpm_devid attestor with Keylime-backed attestation.
+# Keylime is the single TPM authority; this plugin queries its
+# attestation results from the posture-current ConfigMap.
+#
+# See deploy/cascade-timing.md for revocation cascade timing.
+
+server:
+  bind_address: 0.0.0.0
+  bind_port: 8081
+  data_dir: /var/lib/spire/server
+  log_level: INFO
+  trust_domain: guild-a.guildhouse.io
+  ca_ttl: 8760h       # 1 year
+  default_x509_svid_ttl: 1h
+  default_jwt_svid_ttl: 5m
+
+plugins:
+  NodeAttestor:
+    # Primary: Keylime-backed attestation for nodes with hardware TPM.
+    # Reads posture-current ConfigMap via volume mount.
+    keylime:
+      plugin_cmd: /opt/spire/plugins/keylime-attestor
+      plugin_data:
+        source: configmap
+        posture_configmap_path: /var/run/posture/posture-current
+        max_attestation_age_secs: 600
+
+    # Fallback: K8s PSAT for cloud nodes without hardware TPM.
+    k8s_psat:
+      plugin_data:
+        clusters:
+          local:
+            service_account_allow_list:
+              - spire:spire-agent
+
+  KeyManager:
+    guildhouse_substrate:
+      plugin_cmd: /opt/spire/plugins/substrate-keymanager
+      plugin_data:
+        trust_domain: guild-a.guildhouse.io
+        governance_addr: governance.quartermaster.svc.cluster.local:50051
+        notary_addr: notary.quartermaster.svc.cluster.local:50051
+        cluster_id: guild-a
+        governance_epoch_seconds: 300
+
+  CredentialComposer:
+    guildhouse_ssh:
+      plugin_cmd: /opt/spire/plugins/ssh-credential-composer
+      plugin_data:
+        trust_domain: guild-a.guildhouse.io
+        governance_addr: governance.quartermaster.svc.cluster.local:50051
+        default_cert_ttl: 5m
+        max_cert_ttl: 1h
+
+  Notifier:
+    guildhouse_governance:
+      plugin_cmd: /opt/spire/plugins/governance-notifier
+      plugin_data:
+        governance_addr: governance.quartermaster.svc.cluster.local:50051
+        ceremony_addr: ceremony.bascule.svc.cluster.local:50052
+        notary_addr: notary.quartermaster.svc.cluster.local:50051
+        cluster_id: guild-a
+        trust_domain: guild-a.guildhouse.io
+        governance_epoch_seconds: 300
+
+  DataStore:
+    sql:
+      plugin_data:
+        database_type: sqlite3
+        connection_string: /var/lib/spire/server/datastore.sqlite3