# Token firewalling is mandatory — error logs and deep history never bubble up to high-tier models

## The firewall

The 4-tier MMA is built around a sharp boundary: each tier's input is *abstracted* relative to the tier above it. Per `docs/MMA_Support/Overview.md:15`:

> "Token Firewalling: Error logs and deep history are never allowed to bubble up to high-tier models. The system relies heavily on abstracted AST views (Skeleton, Curated) rather than raw code when context allows."

The four abstraction layers, in increasing detail:

| Tier | View | What it contains |
|---|---|---|
| 1 (Orchestrator) | Directory map | file names + nested paths only |
| 2 (Tech Lead) | Skeleton View | class/def signatures, params, type hints (no docstrings, no bodies) |
| 2 (Tech Lead) | Curated View | class definitions, docstrings, `# [HOT]` / `@core_logic` bodies; standard bodies replaced with `... # Hidden` |
| 3 (Worker) | Raw View | unredacted, line-by-line source code of the single target file only |

## Why

- The most expensive models (Tier 1, Tier 2) burn context on architectural reasoning. They do not need (and should not receive) raw implementation noise.
- The cheapest models (Tier 3) can read raw code because they only read one file at a time.

## What this means in practice

- A Tier 2 agent reading foreign modules sees Skeleton View, not Raw View.
- A Tier 1 agent does not see code at all — only directory trees + architecture docs.
- AST view generation is the responsibility of `file_cache.py` (or equivalent) — never an LLM call.
- The boundary is enforced by the tool dispatcher, not by prompt instructions.