feat(harness): implement Plan-20 transparent agentic client bridge

Wave 0 + Wave 1 core of the transparent agentic-client integration: a
developer types prompts normally in Claude Code / Codex while every
certified turn still carries a full H1->H7 trace and an H6 record.

- agentic_bridge.py: stdlib-only lifecycle state machine (begin/pre-tool/
  post-tool/telemetry/finalize/abort + report/doctor). Single-model
  invariant (never calls a model), fail-closed at the side-effect point,
  admission TTL + canonical-project/session binding, atomic state under
  .specify/state/agentic-sessions/, secret redaction, null-not-zero H6.
- agentic-lifecycle.schema.json: client-agnostic JSON contract.
- adapters/claude-code + adapters/codex: thin hook renderers + config
  templates that call the core bridge.
- phase-agentic-bridge-tests.sh: C1-C12 acceptance + threat suite (30/30).
- devkit templates/{claude,codex} + windows/install-agentic.ps1
  (install/doctor/uninstall with manifest, path-safe).
- docs/casan Windows + security/bypass guides; plan status -> IMPLEMENTED.
- harden generate-agentops-dashboard.py aggregation against null H6 costs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/casan-devkit/templates/claude/README.md

@@ -0,0 +1,36 @@
+# CASAN Claude Code adoption template (Plan-20)
+
+Drop `settings.json` into the target repo as `.claude/settings.json` (the
+installer does this). It wires the four Claude Code lifecycle hooks
+(`UserPromptSubmit`, `PreToolUse`, `PostToolUse`, `Stop`) to the CASAN agentic
+bridge so a developer can type prompts normally while every certified turn still
+carries an H1→H7 trace and an H6 record.
+
+- The hook command resolves the repo root via `$CLAUDE_PROJECT_DIR`, so **no
+  machine-specific path is committed**.
+- It invokes `packages/casan-harness/adapters/claude-code/claude_hook.py`, a thin
+  renderer that calls the core bridge. The bridge **never runs a model** — Claude
+  remains the sole model executor (single-model invariant).
+- This is a **`project_hook`** integration: strong for a trusted project, but a
+  member who can edit `.claude/settings.json` can disable it. For organization
+  enforcement use a managed/pinned deployment (`managed_hook`) — see
+  `docs/casan/CASAN_AGENTIC_CLIENT_SECURITY.md`.
+
+## Install (cross-platform)
+
+```bash
+packages/casan-devkit/install.sh --target <repo> --project <id>
+# then enable the agentic client hooks:
+cp packages/casan-devkit/templates/claude/settings.json <repo>/.claude/settings.json
+```
+
+Windows: use `packages/casan-devkit/windows/install-agentic.ps1 -Client claude`.
+
+## Feature flags (environment)
+
+| Variable | Default | Meaning |
+|---|---|---|
+| `CASAN_AGENTIC_BRIDGE_ENABLED` | `1` | Master on/off. |
+| `CASAN_AGENTIC_ENFORCEMENT_MODE` | `observe` | `observe` (telemetry-only, never certified) → `enforce` (gates + certification). |
+| `CASAN_AGENTIC_INTEGRATION_MODE` | `project_hook` | `project_hook` / `managed_hook` / `casan_owned`. |
+| `CASAN_AGENTIC_CLIENT_ALLOWLIST` | (unset) | Comma list; clients outside it are `observed_only`. |

packages/casan-devkit/templates/claude/settings.json

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+{
+  "//": "CASAN Plan-20 Claude Code project hooks. Commit this as .claude/settings.json in the target repo (the devkit installer does this). Commands self-resolve the repo root via $CLAUDE_PROJECT_DIR — no machine-specific path is baked in. Secrets and absolute paths must NOT be added here.",
+  "hooks": {
+    "UserPromptSubmit": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 \"$CLAUDE_PROJECT_DIR/packages/casan-harness/adapters/claude-code/claude_hook.py\" --event UserPromptSubmit",
+            "timeout": 15
+          }
+        ]
+      }
+    ],
+    "PreToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 \"$CLAUDE_PROJECT_DIR/packages/casan-harness/adapters/claude-code/claude_hook.py\" --event PreToolUse",
+            "timeout": 15
+          }
+        ]
+      }
+    ],
+    "PostToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 \"$CLAUDE_PROJECT_DIR/packages/casan-harness/adapters/claude-code/claude_hook.py\" --event PostToolUse",
+            "timeout": 15
+          }
+        ]
+      }
+    ],
+    "Stop": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 \"$CLAUDE_PROJECT_DIR/packages/casan-harness/adapters/claude-code/claude_hook.py\" --event Stop",
+            "timeout": 15
+          }
+        ]
+      }
+    ]
+  }
+}