# Whole mutator-class lease gate

WI-2 adds the framework-native authorization boundary for Claude (including the supported Claudex overlay) and Pi. Every runtime-reported tool name reaches the lease broker before execution. The gate classifies capabilities by the whole tool class; it never parses a Bash command to decide whether that particular string looks read-only.

## Default-deny policy

While a session is not VERIFIED, only these exact classes are allowed:

- Claude: `Read`, `Grep`, `Glob`, `Ls`, `Find`
- Pi: `read`, `grep`, `find`, `ls`
- Both runtimes: the fixed `mosaic_context_recover` primitive

Every other built-in, unknown tool, and custom/MCP tool is consequential by default and is denied. This includes Claude `Bash`, `Edit`, `Write`, and `NotebookEdit`, plus Pi `bash`, `edit`, and `write`. A compromised model therefore cannot bypass Mosaic wrappers by selecting raw `git`, `curl`, `kubectl`, provider, deployment, or filesystem commands inside a generic mutator—the generic mutator itself is blocked before its input executes.

## Broker-owned transition order

The authenticated broker is the sole lease writer:

1. `begin_verification` revokes existing authority and pending tokens first, then records `PENDING_VERIFICATION` and mints one WI-1 single-use promotion token bound to the exact cycle.
2. `promote_lease` accepts only that session/generation/binding/token combination.
3. Token consumption commits before the volatile lease becomes VERIFIED. Promotion is last and cannot be reached directly from UNVERIFIED.
4. `revoke_lease`, a runtime-generation increase, broker restart, or monotonic expiry removes mutator authority.

The initial TTL is capped at the ratified 300-second maximum. A caller may request a shorter positive TTL but cannot lengthen the maximum. Dual compaction-hook miss within an unexpired lease remains the ratified bounded T-A residual; once either observer revokes or TTL expires, the next consequential tool is denied.

A receipt is only a future promotion prerequisite. It is not an obedience, residency, or safety proof and never replaces this mechanical gate.

## Runtime adapters

`launch-runtime.py` registers itself with the broker and then `exec`s Claude or Pi so PID/starttime remain the authenticated parent anchor. It exports only the broker-minted session ID and current generation to descendants.

- Claude installs `mutator-gate.py` as an all-tools (`.*`) `PreToolUse` hook.
- `mosaic claudex` and `mosaic yolo claudex` preserve their isolated `CLAUDE_CONFIG_DIR`, merge the mandatory hook into that isolated `settings.json`, and use the same register-before-exec launcher. Malformed or symlinked isolated settings deny launch.
- Pi invokes the same executable from its `tool_call` handler.

The executable submits the runtime's actual tool name to `authorize_tool`. Missing identity, malformed input/reply, timeout, broker unavailability, or denial exits with status 2 and blocks fail-closed.

## Runtime-launch choke-point and permanent guard

Every repository-owned Claude/Pi launch entry converges on `launch-runtime.py`, either directly or through `mosaic` → `execLeaseGatedRuntime`. PRDY init/update and QA remediation invoke the wrapper directly so their existing prompts, dangerous-permission flags, working directory, and environment survive without skipping broker registration. `@mosaicstack/coord` rewrites direct Claude commands to `mosaic claude` and rejects unknown custom Claude launchers.

`check-runtime-launches.py` is the permanent completeness guard. It scans production shell, TypeScript/JavaScript, Python, and data launch definitions under `packages/`, `apps/`, `plugins/`, and `tools/`; direct literal, absolute-path, process-API, and dynamic runtime launches fail. It is mandatory in `@mosaicstack/mosaic`'s test script, so root CI fails when a future entry does not name the wrapper, `execLeaseGatedRuntime`, or a gated `mosaic` launch. Synthetic scanner tests prove representative bypass forms are rejected, while real-socket tests prove PRDY init/update and QA receive broker sessions and deny an unverified mutator.

The live inventory is emitted by:

```bash
python3 packages/mosaic/framework/tools/lease-broker/check-runtime-launches.py --root . --json
```

| Production launch family                               | Gated entries |
| ------------------------------------------------------ | ------------: |
| `@mosaicstack/coord` default/configured Claude command |             2 |
| Fleet runtime start                                    |             1 |
| QA remediation + generated QA command                  |             2 |
| Orchestrator command construction/session launches     |             3 |
| PRDY init/update                                       |             2 |
| Mosaic Claude/Pi/Claudex adapter and wrapper boundary  |             4 |
| **Total**                                              |   **14 / 14** |

## Assurance boundary

This closes T-A after an observer fires or lease expiry and T-B for in-runtime tool calls. Hook/extension absence, a runtime executing outside the gated launcher, ptrace/same-UID broker replacement, and other fully rotted behavior remain T-C. Server-side branch protection and required PR review/CI remain the irreducible line for protected repository mutations.