docs(fermata): redesign READMEs with polished formatting and examples

Rewrote both the monorepo and export READMEs with a punchy tagline, status
table, realistic before/after scenarios (including the bash bypass case), full
configuration reference, and Claude Code hook integration guide.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -1,17 +1,46 @@
 # dirigent_fermata
 
-`𝄐 fermata` — a fast, harness-agnostic guard that blocks AI coding agents from reading, writing, or executing things they shouldn't.
+**A fast, harness-agnostic policy gate for AI coding agents.**
 
-Reads `.botignore` (gitignore syntax) and an optional `botignore.toml` for advanced rules. Designed to be called from agent hooks, used as an MCP server (future), or consumed as a library.
+Drop a `.botignore` file in your project root. Fermata reads it and blocks your agent from reading, writing, or running things it shouldn't — before the tool call happens.
 
-## Status
+```
+.env
+.env.*
+secrets/**
+conf/localsettings.yaml
+```
 
-v0.1 — first releasable slice:
+That's all it takes.
-- Library: `Op`, `Decision`, `Policy::check`, `Policy::check_command`, project-root walk-up, `.botignore` walker (via `ignore`), `botignore.toml` parsing, path identification heuristics.
-- CLI: `fermata check <path>...`, `fermata hook --harness <name>`.
-- Harness: Claude Code (PreToolUse) only.
 
-Out of scope for v0.1: Codex, Gemini, MCP server, audit log, filesystem watcher.
+---
+
+## Why Fermata
+
+AI coding agents are powerful, but they don't have an innate sense of "don't touch `.env`." Native hook systems in tools like Claude Code let you intercept every file operation — but wiring up your own secure, fast hook for each project is friction. Fermata is that hook, ready to drop in.
+
+- **Fast** — written in Rust; ~1–5ms per call. Hooks fire on every read, write, and bash operation. Python cold-start (~50–150ms) compounds fast. Fermata doesn't.
+- **Familiar syntax** — `.botignore` uses gitignore rules via the `ignore` crate (the same engine powering ripgrep).
+- **Per-operation control** — `botignore.toml` lets you block writes to `vendor/**` while still allowing reads, or deny specific bash patterns without touching path rules.
+- **Harness-agnostic** — plain CLI exit codes work from any shell wrapper; the hook adapter speaks Claude Code's JSON natively.
+
+---
+
+## Status: v0.1
+
+| Component | Status |
+|-----------|--------|
+| Library (`Op`, `Decision`, `Policy::check`, `Policy::check_command`) | Done |
+| `.botignore` walker (project-root walk-up, gitignore semantics) | Done |
+| `botignore.toml` parser (read / write / bash namespaces) | Done |
+| Path identification heuristics | Done |
+| CLI: `fermata check <path>...` | Done |
+| CLI: `fermata hook --harness claude` | Done |
+| Claude Code PreToolUse adapter | Done |
+
+Out of scope for v0.1: Codex / Gemini hook adapters, MCP server mode, audit log, filesystem watcher.
+
+---
 
 ## Install
 
@@ -23,41 +52,163 @@ cargo install --path crates/dirigent_fermata --features cli
 
 This installs the `fermata` binary into `~/.cargo/bin/`.
 
-## Quick start
+---
+
+## Usage
+
+### Checking a path
 
 ```bash
-# As a CLI
 fermata check --op read /path/to/.env
-echo $?  # 1 if blocked, 0 if allowed
+# exit 1 — blocked
+# stderr: blocked by rule ".env" in /your/project/.botignore
 
-# As a Claude Code hook
+fermata check --op write /path/to/src/main.rs
+# exit 0 — allowed
+```
+
+### Claude Code hook adapter
+
+```bash
 fermata hook --harness claude < hook_payload.json
 ```
 
+Reads the PreToolUse JSON from stdin, extracts the tool name and path or command, applies policy, and emits the Claude-shaped JSON response. The hook's exit code is always `0`; the verdict is in the JSON body.
+
+---
+
 ## Configuration
 
-`.botignore` (gitignore syntax, applies to read + write):
+### `.botignore` — the 80% case
-```
+
+Create a `.botignore` at your project root. Gitignore syntax. Blocks both reads and writes.
+
+```gitignore
+# Secrets
 .env
 .env.*
 secrets/**
+
+# Local config overrides
+conf/localsettings.yaml
+conf/localtestsettings.yaml
+
+# Generated files — let the tools rebuild them, not patch them
+dist/**
+*.lock
 ```
 
-`botignore.toml` (per-op rules):
+Fermata walks up from the target file to find the nearest `.botignore`, so it works correctly even when an agent changes directory.
+
+### `botignore.toml` — per-operation rules
+
+For cases where `.botignore`'s uniform read+write block isn't granular enough:
+
 ```toml
 [read]
-patterns = [".env*", "secrets/**"]
+# Block reading secrets outright
+patterns = [".env*", "secrets/**", "conf/localsettings.yaml"]
 
 [write]
+# Allow reading vendor code but block patching it
 patterns = ["vendor/**", "*.lock"]
 
 [bash]
-deny = ["rm -rf /", "git push --force*"]
+# Hard-block destructive or exfiltrating commands
+deny = [
+  "rm -rf /",
+  "curl * | sh",
+  "git push --force*",
+]
+# Ask before any removal or move
 ask = ["rm:*", "mv:*"]
+# Narrow allowlist for automated commands
 allow_prefixes = ["make test", "git checkout:*"]
 ```
 
+---
+
+## How it fits into Claude Code
+
+Add fermata as a `PreToolUse` hook in `.claude/settings.json`:
+
+```json
+{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "Bash|Read|Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "fermata hook --harness claude"
+          }
+        ]
+      }
+    ]
+  }
+}
+```
+
+When Claude attempts a `Read(.env)`, `Write(vendor/foo.js)`, or `Bash(rm ./secrets/key.pem)`, fermata intercepts the call, checks policy, and returns a deny with a human-readable reason — before any damage is done.
+
+---
+
+## Real-world scenario
+
+A project has `.env`, `conf/localsettings.yaml`, and a `vendor/` tree it doesn't want patched. With `.botignore`:
+
+```gitignore
+.env
+.env.*
+conf/localsettings.yaml
+vendor/**
+```
+
+Claude attempts to read credentials:
+
+```
+Tool: Read
+Path: ./conf/localsettings.yaml
+Decision: BLOCK — matched rule "conf/localsettings.yaml" (.botignore)
+```
+
+Claude attempts to read application code:
+
+```
+Tool: Read
+Path: ./src/app/main.rs
+Decision: ALLOW
+```
+
+Claude attempts to run `cat .env` via bash — which would bypass a path-only check:
+
+```toml
+# botignore.toml
+[bash]
+deny = ["cat .env*", "cat conf/localsettings*"]
+```
+
+```
+Tool: Bash
+Command: cat .env
+Decision: BLOCK — matched bash deny rule "cat .env*"
+```
+
+---
+
+## Architecture
+
+Three concentric layers; nothing inner imports from anything outer:
+
+- **`core/`** — harness-unaware, sync. Types, `.botignore` walker, `botignore.toml` parser, `Policy::check` / `check_command`, path extraction.
+- **`harness/`** — `HarnessAdapter` trait over a normalized `ToolCall`. Each adapter lives in its own submodule, feature-gated.
+- **`bin/fermata.rs`** — the only place `clap`, stdio, and exit codes appear.
+
+---
+
 ## See also
 
 - `docs/tools/fermata.md` — Dirigent integration plan
-- `docs/workpad/brainstorm/fermata.md` — full product spec
+- `docs/workpad/brainstorm/fermata.md` — full product spec and field notes
+- `docs/architecture/crates.md` — crate dependency map