/policy-algebra <target>                      # generate rules
/policy-algebra <target> --write <path>       # generate + persist raw block
/policy-algebra --verify <frozen> <candidate> # drift check

if target is a readable file path:
    mode = SHALLOW
    input = read(target)
else:
    mode = DEEP
    input = target

ALGEBRA:
```starlark
<raw frozen starlark block, as /review-loop approved>

If `--write <path>` was supplied, write the raw Starlark block to that path and include `FILE: <path>` in the return block.

## `--verify` flow

1. Read both files.
2. Extract first ` ```starlark ` fenced block from each file.
3. Normalize both blocks (strip trailing whitespace, collapse blank lines, trim edges).
4. If equal → print `MATCH`, exit 0. Else → print `DRIFT` + unified diff, exit 1.

Use the following bash to verify drift — no external dependencies needed:

```bash
# policy-algebra verify — inline, no dependencies
# Usage: bash verify.sh <frozen_file> <candidate_file>
normalize() { sed 's/[[:space:]]*$//' | sed '/^$/d'; }
extract_starlark() { sed -n '/^```starlark/,/^```$/p' "$1" | sed '1d;$d'; }

FROZEN=$(extract_starlark "$1" | normalize)
CANDIDATE=$(extract_starlark "$2" | normalize)

if [ "$FROZEN" = "$CANDIDATE" ]; then
  echo "MATCH"
  exit 0
else
  echo "DRIFT"
  diff <(echo "$FROZEN") <(echo "$CANDIDATE")
  exit 1
fi

# policy-algebra governance — self-hosted
# FROZEN — do not edit; regenerate via /policy-algebra

DEFAULTS = {
    "min_invariants": 2,
    "exit_codes": {"match": 0, "drift": 1, "input_error": 2, "internal_error": 3},
    "required_output_fields": ["ALGEBRA", "REVIEW_ROUNDS", "PANEL", "STATUS"],
    "converged_status": "CONVERGED",
}

# SELECT_MODE: file path → SHALLOW; intent string → DEEP.
def SELECT_MODE(target):
    if is_readable_file(target):
        return "SHALLOW"
    return "DEEP"

# SHALLOW_OR_DEEP: fall through to DEEP when extraction yields < min_invariants or is ambiguous.
def SHALLOW_OR_DEEP(invariants, ambiguous):
    if len(invariants) < DEFAULTS["min_invariants"] or ambiguous:
        return "DEEP"
    return "SHALLOW"

# EXTRACT_BLOCK: use first starlark fence only; multiple blocks → first wins.
def EXTRACT_BLOCK(fences):
    if len(fences) == 0:
        return None
    return fences[0]

# OUTPUT_VALID: output must carry all required fields; STATUS=CONVERGED only after review-loop.
def OUTPUT_VALID(output, review_loop_passed):
    fields_present = all([f in output for f in DEFAULTS["required_output_fields"]])
    converged_ok = output.get("STATUS") != DEFAULTS["converged_status"] or review_loop_passed
    return fields_present and converged_ok

# VERIFY: canonicalize both blocks and compare; never modify source files.
def VERIFY(frozen_canon, candidate_canon):
    if frozen_canon == candidate_canon:
        return DEFAULTS["exit_codes"]["match"]
    return DEFAULTS["exit_codes"]["drift"]

# EXIT_CODE: map outcome strings to numeric codes.
def EXIT_CODE(outcome):
    return DEFAULTS["exit_codes"].get(outcome, DEFAULTS["exit_codes"]["internal_error"])