#!/usr/bin/env python3
# /// script
# requires-python = ">=3.10"
# dependencies = []
# ///
"""
tome knowledge.py — Deterministic knowledge-layer tool for the tome skill family.

Subcommands:
  bootstrap             Scaffold wiki/ and navigate skill supporting files.
  refresh               Re-generate status:generated files; report authored/stub candidates.
  context <path>        Resolve navigation context for a target path.
  check                 Validate knowledge-layer health; exit 1 on errors.
  impact [paths...]     Analyze which wiki docs are affected by changed source paths.

Usage (from repo root, via Justfile module):
  just tome <subcommand> [args]

Or directly:
  uv run -q --script <path-to-tome>/bin/knowledge.py <subcommand> [args]
"""

from __future__ import annotations

import argparse
import json
import re
import subprocess
import sys
from pathlib import Path, PurePosixPath
from typing import Any, NamedTuple

# ---------------------------------------------------------------------------
# Constants
# ---------------------------------------------------------------------------

EXCLUDED_DIRS = {
    ".git", "target", "node_modules", "wiki", "dist", "archive", "__pycache__",
}

CONTROL_NAMES = ("CLAUDE.md", "AGENTS.md")
WIKI_SUBDIR = "wiki"
CODEBASE_SUBDIR = "codebase"
BOOT_MD_REL = "wiki/boot.md"
WIKI_README_REL = "wiki/README.md"
WIKI_NAV_REL = "wiki/NAV.md"
WIKI_CODEBASE_NAV_REL = "wiki/codebase/NAV.md"
WIKI_INVENTORY_REL = "wiki/.inventory.md"
WIKI_CODEBASE_INVENTORY_REL = "wiki/codebase/.inventory.md"

# Canonical H2 order
CANONICAL_SECTIONS = ["Load", "Warnings", "Handoff"]

# Top-level dirs that are clearly source/code (not meta)
TOP_LEVEL_SOURCE_DIRS_HINTS = {"src", "crates", "scripts", "assets", "docs", "experiments"}

# ---------------------------------------------------------------------------
# Exit codes
# ---------------------------------------------------------------------------

EXIT_OK = 0
EXIT_CHECK_ERRORS = 1   # check: >=1 error-severity finding
EXIT_USAGE = 2           # context: path outside repo / nonexistent / invalid args
EXIT_REPO_DISCOVERY = 3  # not a git repo
EXIT_PARSE = 4           # parse failure (context)
EXIT_INTERNAL = 5        # internal error (bootstrap/refresh)

# ---------------------------------------------------------------------------
# Repository root discovery
# ---------------------------------------------------------------------------

def find_repo_root() -> Path:
    """Discover repo root via git rev-parse --show-toplevel."""
    try:
        result = subprocess.run(
            ["git", "rev-parse", "--show-toplevel"],
            capture_output=True, text=True, check=True
        )
        return Path(result.stdout.strip())
    except (subprocess.CalledProcessError, FileNotFoundError):
        print("Repository discovery failed: not a git repository", file=sys.stderr)
        sys.exit(EXIT_REPO_DISCOVERY)


def to_posix_rel(path: Path, root: Path) -> str:
    """Return a POSIX-separator, repo-relative string for a path."""
    try:
        rel = path.relative_to(root)
    except ValueError:
        rel = path
    return rel.as_posix()


def posix_rel(path: Path, root: Path) -> str:
    return to_posix_rel(path, root)

# ---------------------------------------------------------------------------
# Filesystem traversal helpers
# ---------------------------------------------------------------------------

def should_exclude(name: str) -> bool:
    """Return True if a directory name should be excluded from traversal."""
    return name in EXCLUDED_DIRS or name.startswith(".")


def walk_dirs(root: Path, include_root: bool = False):
    """Yield all non-excluded directories under root (breadth-first), optionally root itself."""
    if include_root:
        yield root
    stack = [root]
    while stack:
        current = stack.pop()
        try:
            entries = sorted(current.iterdir(), key=lambda p: p.name)
        except PermissionError:
            continue
        for entry in entries:
            if entry.is_dir() and not should_exclude(entry.name):
                yield entry
                stack.append(entry)


def top_level_dirs(root: Path) -> list[Path]:
    """Return sorted top-level directories that are not excluded."""
    result = []
    try:
        for entry in sorted(root.iterdir(), key=lambda p: p.name):
            if entry.is_dir() and not should_exclude(entry.name):
                result.append(entry)
    except PermissionError:
        pass
    return result


def find_control_file(directory: Path) -> Path | None:
    """Return the effective control file for a directory (CLAUDE.md wins, else AGENTS.md)."""
    claude = directory / "CLAUDE.md"
    agents = directory / "AGENTS.md"
    if claude.exists():
        return claude
    if agents.exists():
        return agents
    return None


def has_both_control_files(directory: Path) -> bool:
    return (directory / "CLAUDE.md").exists() and (directory / "AGENTS.md").exists()


def find_all_control_files(root: Path) -> list[Path]:
    """Return sorted list of all control files in the repo (excluding excluded dirs)."""
    result = []
    for d in walk_dirs(root, include_root=True):
        for name in CONTROL_NAMES:
            f = d / name
            if f.exists():
                result.append(f)
    return sorted(result)


# ---------------------------------------------------------------------------
# Front-matter parsing (hand-rolled, stdlib only)
# ---------------------------------------------------------------------------

class FrontMatter(NamedTuple):
    status: str | None        # generated / authored / stub / None
    source_paths: list[str]   # list of repo-relative POSIX paths
    raw: str                  # the raw front-matter block (without --- delimiters)
    present: bool             # was a front-matter block found at all?


def parse_frontmatter(text: str) -> tuple[FrontMatter, str]:
    """
    Parse YAML front-matter from a markdown file.
    Returns (FrontMatter, body_without_frontmatter).
    Only handles 'status:' and 'source-paths:' fields.
    """
    if not text.startswith("---"):
        return FrontMatter(None, [], "", False), text

    # Find closing ---
    rest = text[3:]
    # skip optional newline
    if rest.startswith("\n"):
        rest = rest[1:]
    end = rest.find("\n---")
    if end == -1:
        return FrontMatter(None, [], "", False), text

    raw = rest[:end]
    body = rest[end + 4:]  # skip \n---
    if body.startswith("\n"):
        body = body[1:]

    status = None
    source_paths: list[str] = []

    in_source_paths = False
    for line in raw.splitlines():
        stripped = line.strip()
        # Continuation of a multi-line YAML list (indented "- item" lines)
        if in_source_paths:
            if stripped.startswith("- "):
                val = stripped[2:].strip().strip('"').strip("'")
                if val:
                    source_paths.append(val)
                continue
            else:
                in_source_paths = False
        if stripped.startswith("status:"):
            val = stripped[len("status:"):].strip().strip('"').strip("'")
            status = val
        elif stripped.startswith("source-paths:"):
            val = stripped[len("source-paths:"):].strip()
            # parse simple inline list: [a, b] or []
            if val.startswith("[") and val.endswith("]"):
                inner = val[1:-1].strip()
                if inner:
                    source_paths = [p.strip().strip('"').strip("'") for p in inner.split(",") if p.strip()]
            elif not val:
                # Multi-line YAML list follows on subsequent lines
                in_source_paths = True

    return FrontMatter(status, source_paths, raw, True), body


def render_frontmatter(status: str, source_paths: list[str]) -> str:
    """Render a front-matter block string (without outer --- lines)."""
    if source_paths:
        paths_str = ", ".join(f"{p}" for p in source_paths)
        sp_line = f"source-paths: [{paths_str}]"
    else:
        sp_line = "source-paths: []"
    return f"status: {status}\n{sp_line}"


def render_frontmatter_block(status: str, source_paths: list[str]) -> str:
    """Render complete ---...--- front-matter block."""
    return f"---\n{render_frontmatter(status, source_paths)}\n---\n"


# ---------------------------------------------------------------------------
# Control file parsing (CLAUDE.md / AGENTS.md)
# ---------------------------------------------------------------------------

INCLUDE_LINE_RE = re.compile(r"^@([A-Za-z0-9_./\\-]+)\s*$")


def expand_includes(text: str, base_dir: Path, depth: int = 0) -> str:
    """Expand `@path` include lines (the Claude Code @-include convention).

    A line consisting solely of `@relative/path` is replaced by that file's
    content, resolved relative to base_dir. Recursion is capped to avoid cycles.
    Unresolvable includes are kept verbatim.
    """
    if depth >= 3 or "@" not in text:
        return text
    out_lines = []
    for line in text.splitlines():
        m = INCLUDE_LINE_RE.match(line.strip())
        if m:
            inc_path = (base_dir / m.group(1)).resolve()
            if inc_path.is_file():
                try:
                    inc_text = inc_path.read_text(encoding="utf-8", errors="replace")
                    out_lines.append(expand_includes(inc_text, inc_path.parent, depth + 1))
                    continue
                except OSError:
                    pass
        out_lines.append(line)
    return "\n".join(out_lines)


def is_pure_include(path: Path) -> bool:
    """True if a control file's non-blank lines are all `@path` includes."""
    try:
        text = path.read_text(encoding="utf-8", errors="replace")
    except OSError:
        return False
    lines = [l.strip() for l in text.splitlines() if l.strip()]
    return bool(lines) and all(INCLUDE_LINE_RE.match(l) for l in lines)

class LoadItem(NamedTuple):
    kind: str         # wiki_nav / domain / pattern / layer / link / prose
    label: str        # original label text
    target: str | None  # resolved target path or None for prose
    raw: str          # original bullet text


class ControlFile(NamedTuple):
    path: Path
    rel: str           # repo-relative POSIX
    title: str | None
    area: str | None          # Area: value
    knowledge: str | None     # Knowledge: link target
    load_items: list[LoadItem]
    warnings: list[str]
    handoff: list[str]
    first_para: str | None    # first paragraph after H1 (for purpose seeding)
    section_order: list[str]  # recognized sections in parse order


LOAD_LABEL_MAP = {
    "Local navigation:": "wiki_nav",
    "Domain semantics:": "domain",
    "Required pattern:": "pattern",
    "Layer context:": "layer",
}


def classify_load_label(label: str) -> str:
    for prefix, kind in LOAD_LABEL_MAP.items():
        if label.strip().startswith(prefix.rstrip(":")):
            return kind
    return "link"


MD_LINK_RE = re.compile(r"\[([^\]]*)\]\(([^)]*)\)")


def parse_md_link(text: str) -> tuple[str, str] | None:
    """Return (label, target) or None."""
    m = MD_LINK_RE.search(text)
    if m:
        return m.group(1), m.group(2)
    return None


def parse_control_file(path: Path, root: Path) -> ControlFile:
    """Parse a control file, gracefully degrading on free-form files."""
    try:
        text = path.read_text(encoding="utf-8", errors="replace")
    except OSError:
        return ControlFile(path, posix_rel(path, root), None, None, None, [], [], [], None, [])

    rel = posix_rel(path, root)
    control_dir = path.parent
    text = expand_includes(text, control_dir)

    lines = text.splitlines()

    title: str | None = None
    area: str | None = None
    knowledge: str | None = None
    load_items: list[LoadItem] = []
    warnings_list: list[str] = []
    handoff_list: list[str] = []
    first_para: str | None = None
    section_order: list[str] = []

    current_section: str | None = None
    in_preamble = False
    preamble_lines: list[str] = []
    after_h1 = False

    for line in lines:
        stripped = line.strip()

        # H1
        if stripped.startswith("# ") and not stripped.startswith("## "):
            if title is None:
                raw_title = stripped[2:].strip()
                # Strip suffix after " — "
                if " — " in raw_title:
                    raw_title = raw_title.split(" — ")[0].strip()
                title = raw_title
                in_preamble = True
                after_h1 = True
                current_section = None
            continue

        # H2 section headers
        if stripped.startswith("## "):
            section_name = stripped[3:].strip()
            if in_preamble:
                in_preamble = False
            if section_name in CANONICAL_SECTIONS:
                section_order.append(section_name)
                current_section = section_name
            else:
                current_section = None
            continue

        # Deeper headers — end current section processing but track for H3+
        if stripped.startswith("#"):
            if in_preamble:
                in_preamble = False
            current_section = None
            continue

        # Preamble: Area: and Knowledge: lines
        if in_preamble and after_h1:
            if stripped.startswith("Area:"):
                val = stripped[len("Area:"):].strip()
                if val.startswith("`") and val.endswith("`"):
                    val = val[1:-1]
                area = val if val else None
            elif stripped.startswith("Knowledge:"):
                val = stripped[len("Knowledge:"):].strip()
                link = parse_md_link(val)
                if link:
                    target = link[1]
                    # Resolve: /path = repo-root-relative, else relative to control_dir
                    if target.startswith("/"):
                        resolved = (root / target.lstrip("/")).resolve()
                    else:
                        resolved = (control_dir / target).resolve()
                    knowledge = posix_rel(resolved, root)
                else:
                    knowledge = val if val else None
            elif stripped and not stripped.startswith("#"):
                preamble_lines.append(stripped)

        # Section content
        if current_section == "Load" and stripped.startswith("- "):
            bullet = stripped[2:].strip()
            link = parse_md_link(bullet)
            if link:
                label, target = link
                kind = classify_load_label(label)
                # Resolve target: /path = repo-root-relative, else relative to control_dir
                if not target.startswith(("http://", "https://", "mailto:")):
                    if target.startswith("/"):
                        resolved = (root / target.lstrip("/")).resolve()
                    else:
                        resolved = (control_dir / target).resolve()
                    target_rel = posix_rel(resolved, root)
                else:
                    target_rel = target
                load_items.append(LoadItem(kind, label, target_rel, bullet))
            else:
                load_items.append(LoadItem("prose", "", None, bullet))

        elif current_section == "Warnings" and stripped.startswith("- "):
            warnings_list.append(stripped[2:].strip())

        elif current_section == "Handoff" and stripped.startswith("- "):
            handoff_list.append(stripped[2:].strip())

    # Extract first paragraph from preamble
    if preamble_lines:
        # Join consecutive non-empty preamble lines into paragraph
        para_parts = []
        for pl in preamble_lines:
            if pl:
                para_parts.append(pl)
            else:
                break
        if para_parts:
            first_para = " ".join(para_parts)

    return ControlFile(path, rel, title, area, knowledge, load_items, warnings_list, handoff_list, first_para, section_order)


# ---------------------------------------------------------------------------
# Wiki file helpers
# ---------------------------------------------------------------------------

def read_wiki_file(path: Path) -> tuple[FrontMatter, str]:
    """Read a wiki file, returning parsed front-matter and body."""
    if not path.exists():
        return FrontMatter(None, [], "", False), ""
    text = path.read_text(encoding="utf-8", errors="replace")
    return parse_frontmatter(text)


def write_generated_file(path: Path, content: str, status: str = "generated",
                          source_paths: list[str] | None = None):
    """Write a generated file with front-matter, only if status allows.

    Returns:
        True  = file was created or updated
        False = file was skipped (authored/stub or identical content)
    """
    path.parent.mkdir(parents=True, exist_ok=True)

    full_content = render_frontmatter_block(status, source_paths or []) + "\n" + content

    # If file exists, check status and content
    if path.exists():
        existing = path.read_text(encoding="utf-8", errors="replace")
        fm, _ = parse_frontmatter(existing)
        if fm.present and fm.status in ("authored", "stub"):
            return False  # never clobber authored/stub
        if existing == full_content:
            return False  # already up to date; report as skipped

    path.write_text(full_content, encoding="utf-8")
    return True


def file_is_generated(path: Path) -> bool:
    """Return True if file has status: generated front-matter."""
    if not path.exists():
        return False
    fm, _ = parse_frontmatter(path.read_text(encoding="utf-8", errors="replace"))
    return fm.present and fm.status == "generated"


def find_wiki_docs_for_path(target_dir: Path, root: Path, wiki_root: Path) -> list[dict]:
    """Find wiki documents relevant to a source path.

    Searches:
    1. Codebase mirror: wiki/codebase/<rel>/ — README.md, NAV.md, DOMAIN.md, any .md
    2. All wiki branches: scan wiki/<branch>/ trees for docs whose source-paths
       include the target (or an ancestor of it).
    3. Knowledge: links from the target's control file.

    Returns list of dicts: {path, label, kind, status}
    """
    target_rel = posix_rel(target_dir, root)
    results = []
    seen_paths: set[str] = set()

    def add_doc(doc_path: Path, label: str, kind: str):
        p = posix_rel(doc_path, root)
        if p not in seen_paths and doc_path.exists():
            fm, _ = read_wiki_file(doc_path)
            results.append({
                "path": p,
                "label": label,
                "kind": kind,
                "status": fm.status or "unknown",
            })
            seen_paths.add(p)

    # 1. Codebase mirror — walk up from target to root looking for mirror docs
    check_dir = target_dir
    while True:
        rel = posix_rel(check_dir, root)
        mirror_dir = wiki_root / CODEBASE_SUBDIR / rel if rel and rel != "." else wiki_root / CODEBASE_SUBDIR
        if mirror_dir.exists():
            for md_file in sorted(mirror_dir.glob("*.md")):
                name = md_file.stem.upper()
                if name == "README":
                    add_doc(md_file, "Code orientation", "wiki_readme")
                elif name == "NAV":
                    add_doc(md_file, "Local navigation", "wiki_nav")
                elif name == "DOMAIN":
                    add_doc(md_file, "Domain overview", "wiki_domain")
                else:
                    add_doc(md_file, md_file.stem, "wiki_doc")
            if any(mirror_dir.glob("*.md")):
                break  # found the nearest mirror with content
        if check_dir == root:
            break
        parent = check_dir.parent
        if parent == check_dir:
            break
        check_dir = parent

    # 2. Scan non-codebase wiki branches for docs with matching source-paths
    if wiki_root.exists():
        for branch_dir in sorted(wiki_root.iterdir()):
            if not branch_dir.is_dir():
                continue
            if branch_dir.name == CODEBASE_SUBDIR:
                continue  # already handled above
            if branch_dir.name.startswith("."):
                continue
            # Walk this branch for .md files with source-paths that match target
            for md_file in branch_dir.rglob("*.md"):
                fm, _ = read_wiki_file(md_file)
                if not fm.source_paths:
                    continue
                for sp in fm.source_paths:
                    sp_normalized = sp.rstrip("/")
                    target_normalized = target_rel.rstrip("/")
                    # Match if source-path is the target, an ancestor, or a child
                    if (sp_normalized == target_normalized
                            or target_normalized.startswith(sp_normalized + "/")
                            or sp_normalized.startswith(target_normalized + "/")):
                        name = md_file.stem.upper()
                        branch = branch_dir.name
                        if name == "README":
                            add_doc(md_file, f"Domain knowledge ({branch})", "domain_readme")
                        elif name == "NAV":
                            add_doc(md_file, f"Navigation ({branch})", "domain_nav")
                        else:
                            add_doc(md_file, f"{md_file.stem} ({branch})", "domain_doc")
                        break  # don't add same file twice for multiple source-paths

    # 3. Knowledge: link from control file
    cf = find_control_file(target_dir)
    if cf:
        parsed = parse_control_file(cf, root)
        if parsed.knowledge:
            knowledge_path = root / parsed.knowledge
            if knowledge_path.is_dir():
                # Look for README.md or index in the knowledge dir
                for candidate in ["README.md", "readme.md", "NAV.md"]:
                    kf = knowledge_path / candidate
                    if kf.exists():
                        add_doc(kf, "Knowledge link", "knowledge_ref")
            elif knowledge_path.exists():
                add_doc(knowledge_path, "Knowledge link", "knowledge_ref")

    return results


# ---------------------------------------------------------------------------
# Justfile parsing
# ---------------------------------------------------------------------------

def parse_justfile(root: Path) -> list[tuple[str, str]]:
    """
    Parse a Justfile and return list of (recipe_name, comment) pairs.
    Comments are the # line immediately preceding a recipe.
    """
    justfile = root / "Justfile"
    if not justfile.exists():
        return []

    try:
        text = justfile.read_text(encoding="utf-8", errors="replace")
    except OSError:
        return []

    recipes = []
    lines = text.splitlines()
    last_comment = ""

    for line in lines:
        stripped = line.strip()
        if stripped.startswith("#"):
            last_comment = stripped[1:].strip()
        elif stripped and not stripped.startswith(" ") and not stripped.startswith("\t"):
            # Possible recipe line: name [params]:
            m = re.match(r"^([a-zA-Z0-9_-]+)(?:\s+[^:]+)?:", stripped)
            if m and not stripped.startswith("set ") and not stripped.startswith("export"):
                recipe_name = m.group(1)
                if recipe_name not in ("default",):
                    recipes.append((recipe_name, last_comment))
                last_comment = ""
            else:
                last_comment = ""
        else:
            if not stripped:
                last_comment = ""

    return recipes


# ---------------------------------------------------------------------------
# Toolchain detection
# ---------------------------------------------------------------------------

def detect_toolchains(root: Path) -> dict[str, Any]:
    """Detect toolchains from manifests and files."""
    toolchains = {}

    if (root / "Cargo.toml").exists():
        toolchains["cargo"] = True
        # Read rust edition / toolchain
        rust_toolchain = root / "rust-toolchain.toml"
        if rust_toolchain.exists():
            try:
                t = rust_toolchain.read_text(encoding="utf-8")
                m = re.search(r'channel\s*=\s*"([^"]+)"', t)
                if m:
                    toolchains["rust_channel"] = m.group(1)
            except OSError:
                pass

    if (root / "scripts" / "pyproject.toml").exists():
        toolchains["uv"] = True
        toolchains["uv_project"] = "scripts"

    if (root / "pyproject.toml").exists():
        toolchains["uv"] = True

    if (root / "package.json").exists():
        toolchains["node"] = True

    if (root / "Justfile").exists():
        toolchains["just"] = True

    return toolchains


# ---------------------------------------------------------------------------
# Navigation table generation
# ---------------------------------------------------------------------------

_MD_LINK_RE = re.compile(r"\[([^\]]+)\]\([^)]*\)")


def sanitize_purpose(text: str) -> str:
    """Make text safe for a Markdown table Purpose cell.

    Control-file paragraphs can contain Markdown links, pipes, and newlines.
    Embedding those verbatim corrupts the table and creates false broken-link
    findings (the links resolve relative to the wiki file, not the source file).
    Flatten links to their label, escape pipes, collapse whitespace, truncate.
    """
    if not text:
        return ""
    text = _MD_LINK_RE.sub(r"\1", text)        # [label](url) -> label
    text = " ".join(text.split())               # collapse whitespace/newlines
    text = text.replace("|", "\\|")             # don't break table columns
    if len(text) > 100:
        text = text[:100].rstrip() + "..."
    return text


def get_dir_purpose(directory: Path, root: Path) -> str:
    """
    Return a purpose string for a directory.
    Source: Area: or Knowledge: label in control file, else H1/first_para, else "".
    NEVER invent from dir name. Output is sanitized for table cells.
    """
    cf = find_control_file(directory)
    if cf:
        parsed = parse_control_file(cf, root)
        if parsed.area:
            return sanitize_purpose(parsed.area)
        if parsed.knowledge:
            return sanitize_purpose(parsed.knowledge)
        if parsed.first_para:
            return sanitize_purpose(parsed.first_para)
        if parsed.title:
            return sanitize_purpose(parsed.title)
    return ""


def generate_nav_table(dirs: list[Path], root: Path, wiki_root: Path,
                        nav_from: Path, *, include_empty: bool = False) -> str:
    """
    Generate a markdown nav table using repo-root-relative /path links.
    nav_from: the file that will contain this table (kept for signature compat).
    include_empty: if False, skip rows with no purpose AND no knowledge link.
    """
    rows = []
    for d in dirs:
        rel = posix_rel(d, root)
        purpose = get_dir_purpose(d, root)
        # Local control link — repo-root-relative /path
        cf = find_control_file(d)
        if cf:
            cf_repo_rel = posix_rel(cf, root)
            cf_cell = f"[{cf.name}](/{cf_repo_rel})"
        else:
            cf_cell = "—"

        # Knowledge link: wiki/codebase/<rel>/ if exists — repo-root-relative /path
        wiki_dir = wiki_root / CODEBASE_SUBDIR / rel
        if wiki_dir.exists() and any(wiki_dir.glob("*.md")):
            wiki_repo_rel = posix_rel(wiki_dir, root)
            knowledge_cell = f"[wiki](/{wiki_repo_rel}/)"
        else:
            knowledge_cell = "—"

        # Skip rows with no useful content unless include_empty is True
        if not include_empty and not purpose and knowledge_cell == "—":
            continue

        rows.append((f"`{rel}/`", purpose, cf_cell, knowledge_cell))

    lines = [
        "| Path | Purpose | Local control | Knowledge |",
        "|------|---------|---------------|-----------|",
    ]
    for path_cell, purpose, cf_cell, knowledge_cell in rows:
        lines.append(f"| {path_cell} | {purpose} | {cf_cell} | {knowledge_cell} |")

    return "\n".join(lines)


# ---------------------------------------------------------------------------
# Content generators
# ---------------------------------------------------------------------------

def generate_boot_md(root: Path) -> str:
    """Generate content for boot.md (without front-matter)."""
    sections = []

    # --- What This Project Is ---
    readme = root / "README.md"
    project_name = root.name
    project_desc = ""
    if readme.exists():
        try:
            rtext = readme.read_text(encoding="utf-8", errors="replace")
            rlines = rtext.splitlines()
            for line in rlines:
                s = line.strip()
                if s.startswith("# "):
                    project_name = s[2:].strip()
                    break
            # First non-empty paragraph after H1
            found_h1 = False
            para_lines = []
            for line in rlines:
                s = line.strip()
                if not found_h1:
                    if s.startswith("# "):
                        found_h1 = True
                    continue
                if s.startswith("#"):
                    break
                if s:
                    para_lines.append(s)
                elif para_lines:
                    break
            if para_lines:
                project_desc = " ".join(para_lines)
        except OSError:
            pass

    what_section = f"## What This Project Is\n\n**{project_name}**"
    if project_desc:
        what_section += f"\n\n{project_desc}"
    sections.append(what_section)

    # --- Toolchains ---
    toolchains = detect_toolchains(root)
    tc_lines = ["## Toolchains", ""]
    if toolchains.get("cargo"):
        channel = toolchains.get("rust_channel", "stable")
        tc_lines.append(f"- **Rust / Cargo** — `{channel}` channel")
    if toolchains.get("uv"):
        uv_proj = toolchains.get("uv_project", "scripts")
        tc_lines.append(f"- **Python / uv** — project: `{uv_proj}/`")
    if toolchains.get("node"):
        tc_lines.append("- **Node.js / npm** — `package.json` present")
    if toolchains.get("just"):
        tc_lines.append("- **Just** — task runner (`just --list` for all recipes)")
    sections.append("\n".join(tc_lines))

    # --- Key Folders ---
    dirs = top_level_dirs(root)
    folder_rows = []
    for d in dirs:
        purpose = get_dir_purpose(d, root)
        if purpose:
            folder_rows.append(f"| `{d.name}/` | {purpose} |")
    folder_lines = ["## Key Folders", ""]
    if folder_rows:
        folder_lines.extend(["| Folder | Purpose |", "|--------|---------|"])
        folder_lines.extend(folder_rows)
        folder_lines.append("")
        folder_lines.append("Run `ls` (or check `wiki/codebase/NAV.md`) for the full directory listing.")
    else:
        folder_lines.append("No folder descriptions available yet. Run `ls` to see the directory structure.")
    sections.append("\n".join(folder_lines))

    # --- Essential Commands ---
    recipes = parse_justfile(root)
    cmd_lines = ["## Essential Commands", ""]

    if toolchains.get("just") and recipes:
        essential = {"run", "dev", "server", "check", "build", "test", "test-net", "test-one"}
        cmd_lines.append("**Core recipes** (run via `just <recipe>`):")
        cmd_lines.append("")
        for name, comment in recipes:
            if name in essential:
                if comment:
                    cmd_lines.append(f"- `just {name}` — {comment}")
                else:
                    cmd_lines.append(f"- `just {name}`")
        cmd_lines.append("")
        cmd_lines.append("Run `just --list` for the full set.")
        cmd_lines.append("")

    if toolchains.get("cargo"):
        cmd_lines.append("**Cargo** (Rust build system):")
        cmd_lines.append("")
        cmd_lines.append("- `cargo check --workspace` — type-check all crates")
        cmd_lines.append("- `cargo test --workspace` — run all tests")
        cmd_lines.append("- `cargo build --workspace` — build all crates")
        cmd_lines.append("")

    if toolchains.get("uv"):
        uv_proj = toolchains.get("uv_project", "scripts")
        cmd_lines.append("**Python scripts** (via uv):")
        cmd_lines.append("")
        cmd_lines.append(f"- `uv run --project {uv_proj} scripts/<name>.py` — run a Python script")
        cmd_lines.append("")

    sections.append("\n".join(cmd_lines))

    # --- Where the Knowledge Layer Lives ---
    kl_section = (
        "## Where the Knowledge Layer Lives\n\n"
        "- `wiki/` — Authored and generated wiki documents (navigation, concepts, patterns)\n"
        "- `wiki/boot.md` — This file (project identity and orientation)\n\n"
        "Navigate the wiki via `wiki/NAV.md` or `wiki/codebase/NAV.md`.\n"
        "See the root `CLAUDE.md` for full project guidelines, conventions, and platform notes."
    )
    sections.append(kl_section)

    # --- Where Executable Truth Lives ---
    et_section = (
        "## Where Executable Truth Lives\n\n"
        "Source code is authoritative for current behavior. "
        "Wiki documents describe concepts and provide navigation — they may lag implementation.\n\n"
        "Always inspect source before making claims about current executable behavior."
    )
    sections.append(et_section)

    # --- Critical Universal Warnings ---
    root_cf = find_control_file(root)
    universal_warnings = []
    if root_cf:
        parsed = parse_control_file(root_cf, root)
        universal_warnings = parsed.warnings

    warn_section = "## Critical Universal Warnings\n\n"
    if universal_warnings:
        warn_section += "\n".join(f"- {w}" for w in universal_warnings)
    else:
        warn_section += "(none — see root CLAUDE.md for full project guidelines)"
    sections.append(warn_section)

    body = "# Repository Boot\n\n" + "\n\n".join(sections)
    return body


def generate_wiki_readme(root: Path, wiki_root: Path) -> str:
    """Generate wiki/README.md content (without front-matter)."""
    return (
        "# Wiki\n\n"
        "This directory contains the knowledge layer for the codebase: "
        "navigation maps, authored wiki documents, and generated resources.\n\n"
        "| Section | Description |\n"
        "|---------|-------------|\n"
        "| [`codebase/`](/wiki/codebase/) | Codebase navigation — mirrors the source tree |\n\n"
        "**Note**: Wiki documents describe concepts and provide navigation. "
        "Source code is authoritative for current behavior.\n\n"
        "See [`NAV.md`](/wiki/NAV.md) for a top-level navigation table."
    )


def generate_wiki_nav(root: Path, wiki_root: Path) -> str:
    """Generate wiki/NAV.md content (without front-matter)."""
    dirs = top_level_dirs(root)
    nav_file = wiki_root / "NAV.md"
    table = generate_nav_table(dirs, root, wiki_root, nav_file)
    return (
        "# Repository Navigation\n\n"
        f"{table}\n\n"
        "Only directories with known purpose or wiki coverage are listed. "
        "Run `ls` for the complete directory listing."
    )


def generate_wiki_codebase_nav(root: Path, wiki_root: Path) -> str:
    """Generate wiki/codebase/NAV.md content (without front-matter).

    Maps every directory that holds a control file (the existing CLAUDE.md /
    AGENTS.md structure), so the wiki is a real index of authored guidance from
    day one. The repository root control file is excluded — it is covered by
    boot.md. Directories are listed in repository order.
    """
    cf_dirs = sorted(
        {cf.parent for cf in find_all_control_files(root) if cf.parent != root},
        key=lambda d: posix_rel(d, root),
    )
    nav_file = wiki_root / CODEBASE_SUBDIR / "NAV.md"
    table = generate_nav_table(cf_dirs, root, wiki_root, nav_file)
    intro = (
        "Directories below carry a local control file (`CLAUDE.md` / `AGENTS.md`). "
        "This is the existing authored guidance the wiki ingests and grows from. "
        "Use `just tome context <path>` to resolve the full ancestor chain for any path."
    )
    return f"# Codebase Navigation\n\n{intro}\n\n{table}"


# ---------------------------------------------------------------------------
# Inventory generation (gitignored, curation input)
# ---------------------------------------------------------------------------

def generate_codebase_inventory(root: Path, wiki_root: Path) -> str:
    """Generate exhaustive codebase inventory for curation agents.

    Lists every directory with a control file, plus metadata to help curation
    agents decide what belongs in NAV.md without extra tool calls.
    """
    cf_dirs = sorted(
        {cf.parent for cf in find_all_control_files(root) if cf.parent != root},
        key=lambda d: posix_rel(d, root),
    )

    lines = [
        "# Codebase Inventory",
        "",
        "Generated by `knowledge.py refresh`. **Do not edit** — this file is gitignored",
        "and regenerated on every refresh. Curation agents read this to discover what",
        "exists; they write to `NAV.md` only what earns its place.",
        "",
        "| Path | Purpose | Control file | Wiki mirror | Wiki branches |",
        "|------|---------|-------------|-------------|---------------|",
    ]

    for d in cf_dirs:
        rel = posix_rel(d, root)
        purpose = get_dir_purpose(d, root)

        # Control file info
        cf = find_control_file(d)
        cf_name = cf.name if cf else "—"

        # Wiki codebase mirror
        mirror_dir = wiki_root / CODEBASE_SUBDIR / rel
        has_mirror = mirror_dir.exists() and any(mirror_dir.glob("*.md"))
        mirror_cell = "yes" if has_mirror else "—"

        # Non-codebase wiki branches that reference this path
        branch_hits = []
        if wiki_root.exists():
            for branch_dir in sorted(wiki_root.iterdir()):
                if not branch_dir.is_dir() or branch_dir.name == CODEBASE_SUBDIR:
                    continue
                if branch_dir.name.startswith("."):
                    continue
                for md_file in branch_dir.rglob("*.md"):
                    fm, _ = read_wiki_file(md_file)
                    for sp in fm.source_paths:
                        sp_n = sp.rstrip("/")
                        rel_n = rel.rstrip("/")
                        if sp_n == rel_n or rel_n.startswith(sp_n + "/") or sp_n.startswith(rel_n + "/"):
                            branch_hits.append(branch_dir.name)
                            break
                    else:
                        continue
                    break
        branches_cell = ", ".join(sorted(set(branch_hits))) if branch_hits else "—"

        lines.append(f"| `{rel}/` | {sanitize_purpose(purpose)} | {cf_name} | {mirror_cell} | {branches_cell} |")

    lines.append("")
    lines.append(f"Total: {len(cf_dirs)} directories with control files.")
    lines.append("")
    return "\n".join(lines)


def generate_wiki_inventory(root: Path, wiki_root: Path) -> str:
    """Generate top-level wiki inventory for curation agents.

    Lists all wiki branches and their contents to help curators understand
    wiki coverage without globbing.
    """
    lines = [
        "# Wiki Inventory",
        "",
        "Generated by `knowledge.py refresh`. **Do not edit** — this file is gitignored",
        "and regenerated on every refresh.",
        "",
    ]

    if not wiki_root.exists():
        lines.append("Wiki directory does not exist yet. Run `tome init` to bootstrap.")
        return "\n".join(lines)

    # List wiki branches
    branches = []
    for entry in sorted(wiki_root.iterdir()):
        if not entry.is_dir() or entry.name.startswith("."):
            continue
        md_files = list(entry.rglob("*.md"))
        authored = sum(1 for f in md_files if _file_status(f) == "authored")
        generated = sum(1 for f in md_files if _file_status(f) == "generated")
        stub = sum(1 for f in md_files if _file_status(f) == "stub")
        branches.append((entry.name, len(md_files), authored, generated, stub))

    if branches:
        lines.append("## Branches")
        lines.append("")
        lines.append("| Branch | Files | Authored | Generated | Stub |")
        lines.append("|--------|-------|----------|-----------|------|")
        for name, total, auth, gen, stb in branches:
            lines.append(f"| `{name}/` | {total} | {auth} | {gen} | {stb} |")
        lines.append("")

    # List top-level .md files
    top_files = sorted(f for f in wiki_root.glob("*.md") if not f.name.startswith("."))
    if top_files:
        lines.append("## Top-level files")
        lines.append("")
        for f in top_files:
            status = _file_status(f)
            lines.append(f"- `{f.name}` ({status})")
        lines.append("")

    # Top-level source dirs without any wiki coverage
    lines.append("## Uncovered source directories")
    lines.append("")
    lines.append("Top-level source directories with control files but no wiki branch coverage:")
    lines.append("")
    uncovered = []
    for d in top_level_dirs(root):
        if not find_control_file(d):
            continue
        rel = posix_rel(d, root)
        mirror = wiki_root / CODEBASE_SUBDIR / rel
        has_mirror = mirror.exists() and any(mirror.glob("*.md"))
        if not has_mirror:
            uncovered.append(rel)
    if uncovered:
        for rel in uncovered:
            lines.append(f"- `{rel}/`")
    else:
        lines.append("(all covered)")
    lines.append("")

    return "\n".join(lines)


def _file_status(path: Path) -> str:
    """Return the front-matter status of a wiki file, or 'unknown'."""
    fm, _ = read_wiki_file(path)
    return fm.status or "unknown"


def write_inventory_file(path: Path, content: str):
    """Write an inventory file (always overwritten, no front-matter)."""
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(content, encoding="utf-8")


def seed_nav_stub(path: Path, title: str, intro: str) -> bool:
    """Create a NAV.md as status:stub if it doesn't exist. Never overwrites.

    Returns True if created, False if already exists.
    """
    if path.exists():
        return False
    path.parent.mkdir(parents=True, exist_ok=True)
    content = render_frontmatter_block("stub", []) + "\n"
    content += f"# {title}\n\n"
    content += f"{intro}\n\n"
    content += "<!-- Curate this file: read .inventory.md for the full listing, -->\n"
    content += "<!-- then add only entries that earn their place here. -->\n\n"
    content += "| Path | Why it matters |\n"
    content += "|------|----------------|\n"
    path.write_text(content, encoding="utf-8")
    return True


# ---------------------------------------------------------------------------
# bootstrap subcommand
# ---------------------------------------------------------------------------

def cmd_bootstrap(root: Path) -> int:
    """Create missing scaffold files. Never clobber status:authored files."""
    created = []
    skipped = []
    inventories = []

    wiki_root = root / WIKI_SUBDIR

    # 1. boot.md
    boot_path = root / BOOT_MD_REL
    boot_content = generate_boot_md(root)
    if write_generated_file(boot_path, boot_content):
        created.append(BOOT_MD_REL)
    else:
        skipped.append(BOOT_MD_REL)

    # 2. wiki/README.md
    wiki_readme_path = root / WIKI_README_REL
    wiki_readme_content = generate_wiki_readme(root, wiki_root)
    if write_generated_file(wiki_readme_path, wiki_readme_content):
        created.append(WIKI_README_REL)
    else:
        skipped.append(WIKI_README_REL)

    # 3. wiki/NAV.md — seed as stub if missing, never overwrite
    wiki_nav_path = root / WIKI_NAV_REL
    if seed_nav_stub(wiki_nav_path,
                     "Repository Navigation",
                     "Selective pointers to the most important areas. Not a complete listing — use `ls` for that."):
        created.append(WIKI_NAV_REL)
    else:
        skipped.append(WIKI_NAV_REL)

    # 4. wiki/codebase/NAV.md — seed as stub if missing, never overwrite
    wiki_codebase_nav_path = root / WIKI_CODEBASE_NAV_REL
    if seed_nav_stub(wiki_codebase_nav_path,
                     "Codebase Navigation",
                     "Key entry points into the source tree. Curated from `.inventory.md` — only directories that matter for orientation."):
        created.append(WIKI_CODEBASE_NAV_REL)
    else:
        skipped.append(WIKI_CODEBASE_NAV_REL)

    # 5. Inventory files (always regenerated, gitignored)
    inv_path = root / WIKI_INVENTORY_REL
    write_inventory_file(inv_path, generate_wiki_inventory(root, wiki_root))
    inventories.append(WIKI_INVENTORY_REL)

    cb_inv_path = root / WIKI_CODEBASE_INVENTORY_REL
    write_inventory_file(cb_inv_path, generate_codebase_inventory(root, wiki_root))
    inventories.append(WIKI_CODEBASE_INVENTORY_REL)

    # Report conceptual knowledge: control files without wiki mirrors
    control_files = find_all_control_files(root)
    no_mirror = []
    for cf in control_files:
        cf_dir = cf.parent
        rel = posix_rel(cf_dir, root)
        wiki_mirror = wiki_root / CODEBASE_SUBDIR / rel
        if not wiki_mirror.exists():
            no_mirror.append(rel if rel else "(root)")

    # Print report
    print("=" * 60)
    print("tome bootstrap report")
    print("=" * 60)
    print()
    if created:
        print("Created:")
        for f in created:
            print(f"  + {f}")
        print()
    if skipped:
        print("Skipped (already exist or status:authored/stub):")
        for f in skipped:
            print(f"  ~ {f}")
        print()
    if inventories:
        print("Inventories (gitignored, for curation agents):")
        for f in inventories:
            print(f"  * {f}")
        print()
    if no_mirror:
        print(f"Conceptual knowledge available for authoring later ({len(no_mirror)} dirs):")
        for rel in sorted(no_mirror)[:20]:  # cap display at 20
            print(f"  ? {rel}/CLAUDE.md -> wiki/codebase/{rel}/")
        if len(no_mirror) > 20:
            print(f"  ... and {len(no_mirror) - 20} more")
        print()
    print(f"Control files found: {len(control_files)}")
    print()

    return EXIT_OK


# ---------------------------------------------------------------------------
# refresh subcommand
# ---------------------------------------------------------------------------

def cmd_refresh(root: Path) -> int:
    """Refresh status:generated files and inventories; report authored/stub for review."""
    wiki_root = root / WIKI_SUBDIR
    updated = []
    inventories = []
    proposed = []

    # Files to auto-refresh if status:generated (NAV files excluded — they are
    # now authored/stub and curated by agents, not regenerated by the tool)
    generated_files = [
        (root / BOOT_MD_REL,  lambda: generate_boot_md(root),  []),
    ]

    for path, content_fn, src_paths in generated_files:
        rel = posix_rel(path, root)
        if not path.exists():
            proposed.append(f"{rel} — missing (run bootstrap first)")
            continue
        if not file_is_generated(path):
            proposed.append(f"{rel} — status is not 'generated'; skipped")
            continue
        new_content = content_fn()
        full_content = render_frontmatter_block("generated", src_paths) + "\n" + new_content
        existing = path.read_text(encoding="utf-8", errors="replace")
        if existing != full_content:
            path.write_text(full_content, encoding="utf-8")
            updated.append(rel)

    # Inventory files (always regenerated, gitignored)
    inv_path = root / WIKI_INVENTORY_REL
    write_inventory_file(inv_path, generate_wiki_inventory(root, wiki_root))
    inventories.append(WIKI_INVENTORY_REL)

    cb_inv_path = root / WIKI_CODEBASE_INVENTORY_REL
    write_inventory_file(cb_inv_path, generate_codebase_inventory(root, wiki_root))
    inventories.append(WIKI_CODEBASE_INVENTORY_REL)

    # Scan control files
    control_files = find_all_control_files(root)
    dirs = top_level_dirs(root)

    # Stale checks: wiki mirrors for removed source dirs
    wiki_codebase = wiki_root / CODEBASE_SUBDIR
    if wiki_codebase.exists():
        for wiki_sub in sorted(wiki_codebase.iterdir()):
            if wiki_sub.is_dir():
                source_candidate = root / wiki_sub.name
                if not source_candidate.exists():
                    proposed.append(
                        f"wiki/codebase/{wiki_sub.name}/ — "
                        f"source dir '{wiki_sub.name}/' no longer exists"
                    )

    # New top-level dirs without wiki coverage
    for d in dirs:
        rel = posix_rel(d, root)
        mirror = wiki_root / CODEBASE_SUBDIR / rel
        if not mirror.exists() and find_control_file(d):
            proposed.append(
                f"{rel}/ — has CLAUDE.md but no wiki mirror (candidate for wiki/codebase/{rel}/)"
            )

    # NAV files that are still status:generated (legacy — should be curated)
    for nav_rel in [WIKI_NAV_REL, WIKI_CODEBASE_NAV_REL]:
        nav_path = root / nav_rel
        if nav_path.exists() and file_is_generated(nav_path):
            proposed.append(
                f"{nav_rel} — still status:generated (should be curated to status:authored)"
            )

    # Print report
    print("=" * 60)
    print("tome refresh report")
    print("=" * 60)
    print()
    if updated:
        print("Automatically updated:")
        for f in updated:
            print(f"  * {f}")
        print()
    else:
        print("Automatically updated: (none — all generated files are up to date)")
        print()

    if inventories:
        print("Inventories regenerated (gitignored, for curation agents):")
        for f in inventories:
            print(f"  * {f}")
        print()

    if proposed:
        print("Proposed for review (not automatically changed):")
        for msg in proposed:
            print(f"  ? {msg}")
        print()

    print(f"Control-file inventory: {len(control_files)} files found")
    print()

    return EXIT_OK


# ---------------------------------------------------------------------------
# context subcommand
# ---------------------------------------------------------------------------

class Finding(NamedTuple):
    id: str
    severity: str   # error / warning
    path: str
    message: str
    target: str = ""


def cmd_context(root: Path, target_str: str, as_json: bool = False) -> int:
    """Resolve navigation context for a target path."""
    # 1. Normalize path. Relative paths are repository-relative (the documented
    #    contract), not cwd-relative — the tool is usually invoked from outside
    #    the repo root (e.g. the `just tome` module runs from the plugin dir).
    target = Path(target_str)
    if not target.is_absolute():
        target = root / target
    target = target.resolve()

    # Check outside repo
    try:
        target.relative_to(root)
    except ValueError:
        msg = f"Path '{target_str}' is outside the repository root '{root}'"
        if as_json:
            print(json.dumps({"error": msg, "exit_code": EXIT_USAGE}))
        else:
            print(f"Error: {msg}", file=sys.stderr)
        return EXIT_USAGE

    # Check exists
    if not target.exists():
        msg = f"Path '{target_str}' does not exist"
        if as_json:
            print(json.dumps({"error": msg, "exit_code": EXIT_USAGE}))
        else:
            print(f"Error: {msg}", file=sys.stderr)
        return EXIT_USAGE

    target_rel = posix_rel(target, root)
    target_kind = "directory" if target.is_dir() else "file"

    # 2. Target dir
    target_dir = target if target.is_dir() else target.parent

    # 3. Enumerate ancestor dirs root -> target (inclusive)
    ancestors: list[Path] = []
    current = target_dir
    while True:
        ancestors.append(current)
        if current == root:
            break
        parent = current.parent
        if parent == current:
            break
        current = parent
    ancestors.reverse()  # root first

    # 4. Per ancestor: pick effective control file
    effective_controls: list[dict] = []
    findings: list[Finding] = []

    all_warnings: list[dict] = []
    all_handoff: list[dict] = []
    all_load: list[dict] = []

    for anc in ancestors:
        anc_rel = posix_rel(anc, root)
        # Root is represented as "" not "."
        if anc_rel == ".":
            anc_rel = ""
        cf = find_control_file(anc)
        if cf is None:
            continue

        cf_rel = posix_rel(cf, root)
        effective_controls.append({"path": cf_rel, "ancestor": anc_rel})

        # 5. Parse
        parsed = parse_control_file(cf, root)

        # Aggregate warnings
        for w in parsed.warnings:
            all_warnings.append({"text": w, "source": cf_rel})

        # Aggregate handoff
        for h in parsed.handoff:
            all_handoff.append({"text": h, "source": cf_rel})

        # Aggregate load items
        for item in parsed.load_items:
            if item.target:
                target_path = root / item.target
                if not target_path.exists() and not item.target.startswith(("http://", "https://")):
                    findings.append(Finding(
                        "control.load-link.broken", "warning", cf_rel,
                        f"Load link target not found: '{item.target}'",
                        item.target
                    ))
            all_load.append({
                "label": item.label,
                "kind": item.kind,
                "target": item.target,
                "source": cf_rel,
            })

    # 7. Wiki document discovery
    wiki_root = root / WIKI_SUBDIR
    wiki_docs = find_wiki_docs_for_path(target_dir, root, wiki_root)

    # Mirror info for backward compat (JSON output)
    mirror_info: dict | None = None
    if wiki_docs:
        # First codebase mirror doc determines the mirror path
        for wd in wiki_docs:
            if wd["kind"].startswith("wiki_"):
                mirror_path = str(PurePosixPath(wd["path"]).parent)
                mirror_info = {
                    "path": mirror_path,
                    "documents": wiki_docs,
                }
                break
        if not mirror_info:
            mirror_info = {"path": "", "documents": wiki_docs}

    # 8. Required reading (resolvable Load link targets + wiki docs)
    required_reading = []
    for item in all_load:
        if item["target"] and not item["target"].startswith(("http://", "https://")):
            t_path = root / item["target"]
            if t_path.exists():
                required_reading.append({
                    "path": item["target"],
                    "label": item["label"],
                    "source": item["source"],
                    "kind": item["kind"],
                })

    # Add wiki documents to required reading — authored docs first, then generated
    for wd in wiki_docs:
        if not any(r["path"] == wd["path"] for r in required_reading):
            required_reading.append({
                "path": wd["path"],
                "label": wd["label"],
                "source": "wiki",
                "kind": wd["kind"],
            })

    # 9. Quick top commands from Justfile
    recipes = parse_justfile(root)
    top_commands = []
    important_recipes = ["check", "test", "build", "run", "dev", "tome-check", "tome-context"]
    for name, comment in recipes:
        if name in important_recipes:
            top_commands.append(f"just {name}")
    if not top_commands and recipes:
        top_commands = [f"just {recipes[0][0]}"]

    # Sort findings
    findings.sort(key=lambda f: (0 if f.severity == "error" else 1, f.path))

    if as_json:
        # Enrich required_reading and effective_controls with root_relative_path (/ prefix)
        rr_enriched = [
            {**r, "root_relative_path": f"/{r['path']}"}
            for r in required_reading
        ]
        ec_enriched = [
            {**ec, "root_relative_path": f"/{ec['path']}"}
            for ec in effective_controls
        ]
        output = {
            "schema_version": 2,
            "repository_root": root.as_posix(),
            "target": target_rel,
            "target_kind": target_kind,
            "effective_controls": ec_enriched,
            "warnings": all_warnings,
            "handoff": all_handoff,
            "required_reading": rr_enriched,
            "mirror": mirror_info,
            "top_commands": top_commands,
            "findings": [
                {
                    "id": f.id,
                    "severity": f.severity,
                    "path": f.path,
                    "message": f.message,
                    "target": f.target,
                }
                for f in findings
            ],
        }
        print(json.dumps(output, indent=2))
    else:
        # Human output
        print(f"Context: {target_rel} ({target_kind})")
        print()

        print("Warnings:")
        if all_warnings:
            for w in all_warnings:
                print(f"  - {w['text']} [from {w['source']}]")
        else:
            print("  (none)")
        print()

        print("Read first:")
        if required_reading:
            for r in required_reading:
                status_hint = ""
                # Show authored wiki docs prominently
                if r["source"] == "wiki":
                    wd_match = next((w for w in wiki_docs if w["path"] == r["path"]), None)
                    if wd_match and wd_match["status"] == "authored":
                        status_hint = " (authored)"
                    elif wd_match and wd_match["status"] == "generated":
                        status_hint = " (generated)"
                print(f"  /{r['path']}{status_hint}  — {r['label']}")
        else:
            print("  (none)")
        print()

        if wiki_docs:
            print("Wiki knowledge:")
            for wd in wiki_docs:
                print(f"  /{wd['path']}  [{wd['status']}] — {wd['label']}")
            print("  Use `ls` to verify current directory contents — wiki may lag.")
        else:
            print("Wiki knowledge: (none — no wiki documents cover this path yet)")
        print()

        print("Useful commands:")
        if top_commands:
            for cmd in top_commands:
                print(f"  {cmd}")
        else:
            print("  (run `just --list` for available recipes)")
        print()

        print("Relevant control files:")
        if effective_controls:
            for ec in effective_controls:
                print(f"  /{ec['path']}")
        else:
            print("  (none)")
        print()

        if findings:
            print("Findings:")
            for f in findings:
                print(f"  [{f.severity.upper()}] {f.id}: {f.message} ({f.path})")
            print()

    return EXIT_OK


# ---------------------------------------------------------------------------
# check subcommand
# ---------------------------------------------------------------------------

def strip_fenced_code(text: str) -> str:
    """Return a version of text with fenced code block contents replaced by blank lines."""
    lines = text.splitlines(keepends=True)
    result = []
    in_fence = False
    fence_marker = ""
    for line in lines:
        stripped = line.strip()
        if not in_fence:
            if stripped.startswith("```") or stripped.startswith("~~~"):
                in_fence = True
                fence_marker = stripped[:3]
                result.append(line)  # keep the fence line itself
            else:
                result.append(line)
        else:
            if stripped.startswith(fence_marker) and stripped == fence_marker:
                in_fence = False
                result.append(line)
            else:
                # Replace with blank line to preserve line numbers
                result.append("\n")
    return "".join(result)


def count_h1(text: str) -> int:
    """Count H1 headings in markdown text, skipping fenced code blocks."""
    clean = strip_fenced_code(text)
    count = 0
    for line in clean.splitlines():
        s = line.strip()
        if s.startswith("# ") and not s.startswith("## "):
            count += 1
    return count


def resolve_link_target(target: str, file_dir: Path, root: Path) -> Path:
    """Resolve a markdown link target to an absolute Path.

    Resolution rules:
    - ``/path`` — repo-root-relative (strip leading ``/``, join with ``root``)
    - ``http://`` / ``https://`` — external (caller must skip before calling this)
    - anything else — relative to ``file_dir`` (existing behaviour)
    """
    if target.startswith("/"):
        return (root / target.lstrip("/")).resolve()
    return (file_dir / target).resolve()


def check_markdown_links(path: Path, root: Path) -> list[Finding]:
    """Check local markdown links in a file, skipping fenced code blocks."""
    findings = []
    try:
        text = path.read_text(encoding="utf-8", errors="replace")
    except OSError:
        return findings

    # Strip code blocks so we don't check links inside them
    text = strip_fenced_code(text)

    file_dir = path.parent
    # Find all markdown links
    for m in MD_LINK_RE.finditer(text):
        target = m.group(2).strip()
        # Skip external links, mailto, anchors-only
        if target.startswith(("http://", "https://", "mailto:", "#")):
            continue
        # Strip fragment
        if "#" in target:
            target = target[:target.index("#")]
        if not target:
            continue
        # Resolve: /path = repo-root-relative, else relative to file dir
        resolved = resolve_link_target(target, file_dir, root)
        if not resolved.exists():
            rel_path = posix_rel(path, root)
            findings.append(Finding(
                "link.broken", "error", rel_path,
                f"Broken link target: '{target}'",
                target
            ))
    return findings


def cmd_check(root: Path, as_json: bool = False) -> int:
    """Validate knowledge-layer health."""
    findings: list[Finding] = []
    wiki_root = root / WIKI_SUBDIR

    # --- Check nav resources ---
    boot_path = root / BOOT_MD_REL

    if not boot_path.exists():
        findings.append(Finding(
            "nav.resource.missing", "error",
            BOOT_MD_REL,
            "boot.md is missing — run 'knowledge.py bootstrap' to create it",
        ))

    wiki_readme = root / WIKI_README_REL
    wiki_nav = root / WIKI_NAV_REL
    if not wiki_readme.exists():
        findings.append(Finding(
            "nav.wiki.missing", "warning",
            WIKI_README_REL,
            "wiki/README.md is missing — run 'knowledge.py bootstrap'",
        ))
    if not wiki_nav.exists():
        findings.append(Finding(
            "nav.wiki.missing", "warning",
            WIKI_NAV_REL,
            "wiki/NAV.md is missing — run 'knowledge.py bootstrap'",
        ))

    # --- Check control files ---
    control_files = find_all_control_files(root)
    checked_dirs: set[Path] = set()

    for cf in control_files:
        cf_dir = cf.parent
        rel = posix_rel(cf, root)

        # coexist check — the @AGENTS.md router pattern (CLAUDE.md that is a
        # pure include of AGENTS.md) is a recommended convention, not a clash
        if cf_dir not in checked_dirs:
            checked_dirs.add(cf_dir)
            if has_both_control_files(cf_dir):
                if not (is_pure_include(cf_dir / "CLAUDE.md") or is_pure_include(cf_dir / "AGENTS.md")):
                    findings.append(Finding(
                        "control.coexist", "warning",
                        posix_rel(cf_dir, root),
                        "Both CLAUDE.md and AGENTS.md exist in this directory",
                    ))

        # Pure-include routers delegate all content; the included file is
        # checked on its own, so skip structural checks here
        if is_pure_include(cf):
            continue

        # Parse
        parsed = parse_control_file(cf, root)

        # H1 checks (on include-expanded text, matching how agents see the file)
        try:
            text = expand_includes(cf.read_text(encoding="utf-8", errors="replace"), cf_dir)
        except OSError:
            continue

        h1_count = count_h1(text)
        if h1_count == 0:
            findings.append(Finding(
                "control.h1.missing", "error", rel,
                "Control file has no H1 heading",
            ))
        elif h1_count > 1:
            findings.append(Finding(
                "control.h1.multiple", "error", rel,
                f"Control file has {h1_count} H1 headings (expected 1)",
            ))

        # Section order
        if len(parsed.section_order) > 1:
            expected = [s for s in CANONICAL_SECTIONS if s in parsed.section_order]
            if parsed.section_order != expected:
                findings.append(Finding(
                    "control.section.order", "warning", rel,
                    f"Recognized sections out of canonical order: {parsed.section_order} (expected {expected})",
                ))

        # Load link broken (only for files that actually have Load sections)
        for item in parsed.load_items:
            if item.kind != "prose" and item.target:
                if not item.target.startswith(("http://", "https://")):
                    t_path = root / item.target
                    if not t_path.exists():
                        findings.append(Finding(
                            "control.load-link.broken", "error", rel,
                            f"Load link target not found: '{item.target}'",
                            item.target,
                        ))

        # Check links in control files
        link_findings = check_markdown_links(cf, root)
        # Filter out same findings already caught by load-link.broken
        for lf in link_findings:
            findings.append(lf)

    # --- Check wiki files ---
    if wiki_root.exists():
        for wiki_file in sorted(wiki_root.rglob("*.md")):
            if wiki_file.name.startswith("."):
                continue  # skip inventory files (.inventory.md)
            wrel = posix_rel(wiki_file, root)
            try:
                text = wiki_file.read_text(encoding="utf-8", errors="replace")
            except OSError:
                continue

            fm, body = parse_frontmatter(text)

            if not fm.present:
                findings.append(Finding(
                    "wiki.frontmatter.missing", "warning",
                    wrel,
                    "Wiki file has no front-matter block (add ---\\nstatus: generated\\nsource-paths: []\\n---)",
                ))
            else:
                if fm.status not in ("generated", "authored", "stub"):
                    findings.append(Finding(
                        "wiki.frontmatter.status.invalid", "error",
                        wrel,
                        f"Invalid status value '{fm.status}' (must be generated/authored/stub)",
                    ))
                for sp in fm.source_paths:
                    sp_path = root / sp
                    if not sp_path.exists():
                        findings.append(Finding(
                            "wiki.source-path.missing", "warning",
                            wrel,
                            f"source-paths entry '{sp}' does not exist",
                        ))

            # Check links in wiki files
            link_findings = check_markdown_links(wiki_file, root)
            for lf in link_findings:
                findings.append(lf)

    # --- nav.stale: check nav tables ---
    dirs = top_level_dirs(root)
    dir_names = {d.name for d in dirs}
    dir_rels = {posix_rel(d, root) for d in dirs}

    # Check wiki/NAV.md for stale entries
    for nav_path_rel in [WIKI_NAV_REL, WIKI_CODEBASE_NAV_REL]:
        nav_path = root / nav_path_rel
        if not nav_path.exists():
            continue
        fm_nav, nav_body = parse_frontmatter(
            nav_path.read_text(encoding="utf-8", errors="replace")
        )
        # Extract dir entries from nav table
        for line in nav_body.splitlines():
            m = re.match(r"\|\s*`([^`/]+)/`", line)
            if m:
                listed_name = m.group(1)
                listed_path = root / listed_name
                if not listed_path.exists():
                    findings.append(Finding(
                        "nav.stale", "warning",
                        nav_path_rel,
                        f"Nav table lists '{listed_name}/' but directory does not exist",
                    ))

    # Check for dirs present but not in nav (only top-level that have control
    # files). Applies only to status:generated NAVs — authored NAVs are
    # selective by design (curated pointers, not complete inventories).
    for nav_path_rel in [WIKI_NAV_REL, WIKI_CODEBASE_NAV_REL]:
        nav_path = root / nav_path_rel
        if not nav_path.exists() or not file_is_generated(nav_path):
            continue
        fm_nav, nav_body = parse_frontmatter(
            nav_path.read_text(encoding="utf-8", errors="replace")
        )
        listed_names: set[str] = set()
        for line in nav_body.splitlines():
            m = re.match(r"\|\s*`([^`/]+)/`", line)
            if m:
                listed_names.add(m.group(1))
        for d in dirs:
            if d.name not in listed_names and find_control_file(d):
                findings.append(Finding(
                    "nav.stale", "warning",
                    nav_path_rel,
                    f"Nav table omits '{d.name}/' which has a control file",
                ))

    # Sort: errors first, then by path
    findings.sort(key=lambda f: (0 if f.severity == "error" else 1, f.path))

    error_count = sum(1 for f in findings if f.severity == "error")
    warning_count = sum(1 for f in findings if f.severity == "warning")

    if as_json:
        output = {
            "schema_version": 2,
            "findings": [
                {
                    "id": f.id,
                    "severity": f.severity,
                    "path": f.path,
                    "message": f.message,
                    "remediation": _remediation(f.id),
                }
                for f in findings
            ],
            "summary": {
                "errors": error_count,
                "warnings": warning_count,
            },
        }
        print(json.dumps(output, indent=2))
    else:
        if error_count > 0:
            print("Errors:")
            for f in findings:
                if f.severity == "error":
                    print(f"  {f.path} [{f.id}]")
                    print(f"    {f.message}")
                    rem = _remediation(f.id)
                    if rem:
                        print(f"    -> {rem}")
            print()

        if warning_count > 0:
            print("Warnings:")
            for f in findings:
                if f.severity == "warning":
                    print(f"  {f.path} [{f.id}]")
                    print(f"    {f.message}")
            print()

        if error_count == 0 and warning_count == 0:
            print("No findings. Knowledge layer is healthy.")
            print()

        print(f"Summary: {error_count} errors, {warning_count} warnings")

    return EXIT_CHECK_ERRORS if error_count > 0 else EXIT_OK


# ---------------------------------------------------------------------------
# impact subcommand
# ---------------------------------------------------------------------------

class ImpactHit(NamedTuple):
    wiki_doc: str       # repo-relative POSIX path to the wiki doc
    changed_file: str   # the changed path that triggered the match
    hit_type: str       # direct, directory, control, potential


def cmd_impact(root: Path, changed_paths: list[str]) -> int:
    """Analyze which wiki documents are affected by a set of changed source paths."""
    wiki_root = root / WIKI_SUBDIR

    # Normalize input paths: strip whitespace, make repo-relative POSIX, skip empty
    normalized: list[str] = []
    for p in changed_paths:
        p = p.strip()
        if not p:
            continue
        # Normalize to forward slashes, strip leading ./ or /
        p = p.replace("\\", "/")
        if p.startswith("./"):
            p = p[2:]
        if p.startswith("/"):
            p = p[1:]
        normalized.append(p)

    if not normalized:
        print("No changed paths provided.")
        print()
        print("Usage:")
        print("  knowledge.py impact <path1> [path2 ...]")
        print("  git diff --name-only | knowledge.py impact")
        return EXIT_OK

    # Collect all wiki docs with their source-paths
    wiki_docs: list[tuple[str, list[str]]] = []  # (wiki_rel_path, source_paths)
    if wiki_root.exists():
        for md_file in sorted(wiki_root.rglob("*.md")):
            if md_file.name.startswith("."):
                continue
            fm, _ = read_wiki_file(md_file)
            if fm.source_paths:
                wiki_docs.append((posix_rel(md_file, root), fm.source_paths))

    hits: list[ImpactHit] = []
    seen: set[tuple[str, str, str]] = set()  # (wiki_doc, changed_file, hit_type)

    def add_hit(wiki_doc: str, changed_file: str, hit_type: str):
        key = (wiki_doc, changed_file, hit_type)
        if key not in seen:
            seen.add(key)
            hits.append(ImpactHit(wiki_doc, changed_file, hit_type))

    for changed in normalized:
        changed_normalized = changed.rstrip("/")

        # 1. Direct hits: wiki doc source-paths lists the exact changed file
        for wiki_path, source_paths in wiki_docs:
            for sp in source_paths:
                sp_normalized = sp.rstrip("/")
                if sp_normalized == changed_normalized:
                    add_hit(wiki_path, changed, "direct")

        # 2. Directory hits: wiki doc source-paths lists a parent directory
        for wiki_path, source_paths in wiki_docs:
            for sp in source_paths:
                sp_normalized = sp.rstrip("/")
                # sp is a parent directory of the changed file
                if changed_normalized.startswith(sp_normalized + "/"):
                    add_hit(wiki_path, changed, "directory")

        # 3. Control file hits: CLAUDE.md in directories containing changed files
        # Walk ancestor directories of the changed file
        changed_path = PurePosixPath(changed_normalized)
        parents = list(changed_path.parents)
        # Include the file's directory (parent of the file)
        for parent in parents:
            parent_str = str(parent)
            if parent_str == ".":
                parent_dir = root
            else:
                parent_dir = root / parent_str
            cf = find_control_file(parent_dir)
            if cf:
                cf_rel = posix_rel(cf, root)
                add_hit(cf_rel, changed, "control")

        # 4. Potential stale: wiki docs whose source-paths reference files in
        #    the same module (same top-level directory subtree) as changed files
        # Determine the module prefix of the changed file (first two path segments, or first one)
        parts = changed_normalized.split("/")
        if len(parts) >= 2:
            module_prefix = parts[0] + "/" + parts[1]
        elif len(parts) == 1:
            module_prefix = parts[0]
        else:
            continue

        for wiki_path, source_paths in wiki_docs:
            for sp in source_paths:
                sp_normalized = sp.rstrip("/")
                # Same module but not already a direct or directory hit
                if (sp_normalized.startswith(module_prefix + "/") or sp_normalized == module_prefix):
                    # Only add if not already matched as direct or directory
                    if (wiki_path, changed, "direct") not in seen and \
                       (wiki_path, changed, "directory") not in seen:
                        add_hit(wiki_path, changed, "potential")
                        break  # one match per wiki doc per changed file is enough

    # Output report
    if not hits:
        print("No impact detected.")
        print()
        print(f"Checked {len(normalized)} changed path(s) against {len(wiki_docs)} wiki document(s).")
        return EXIT_OK

    # Group by hit type
    direct_hits = [h for h in hits if h.hit_type == "direct"]
    directory_hits = [h for h in hits if h.hit_type == "directory"]
    control_hits = [h for h in hits if h.hit_type == "control"]
    potential_hits = [h for h in hits if h.hit_type == "potential"]

    print("=" * 60)
    print("tome impact report")
    print("=" * 60)
    print()
    print(f"Changed paths: {len(normalized)}")
    print(f"Wiki documents checked: {len(wiki_docs)}")
    print()

    if direct_hits:
        print("Direct hits (wiki doc source-paths lists the exact changed file):")
        for h in direct_hits:
            print(f"  {h.wiki_doc}")
            print(f"    <- {h.changed_file}")
        print()

    if directory_hits:
        print("Directory hits (wiki doc source-paths lists a parent directory):")
        for h in directory_hits:
            print(f"  {h.wiki_doc}")
            print(f"    <- {h.changed_file}")
        print()

    if control_hits:
        print("Control file hits (CLAUDE.md in ancestor directories of changed files):")
        for h in control_hits:
            print(f"  {h.wiki_doc}")
            print(f"    <- {h.changed_file}")
        print()

    if potential_hits:
        print("Potential stale (wiki docs referencing same module as changed files):")
        for h in potential_hits:
            print(f"  {h.wiki_doc}")
            print(f"    <- {h.changed_file}")
        print()

    # Summary
    total = len(direct_hits) + len(directory_hits) + len(control_hits) + len(potential_hits)
    print(f"Total: {total} impact(s) — "
          f"{len(direct_hits)} direct, {len(directory_hits)} directory, "
          f"{len(control_hits)} control, {len(potential_hits)} potential")

    return EXIT_OK


def _remediation(finding_id: str) -> str:
    return {
        "control.h1.missing": "Add a '# Title' heading as the first H1 in the control file",
        "control.h1.multiple": "Keep exactly one H1 heading in the control file",
        "control.section.order": "Reorder recognized sections: Load -> Warnings -> Handoff",
        "control.load-link.broken": "Fix the link target path in the ## Load section",
        "control.coexist": "Remove one of CLAUDE.md or AGENTS.md from this directory",
        "wiki.frontmatter.missing": "Add YAML front-matter: ---\\nstatus: generated\\nsource-paths: []\\n---",
        "wiki.frontmatter.status.invalid": "Set status to one of: generated, authored, stub",
        "wiki.source-path.missing": "Update source-paths to list existing repo paths",
        "link.broken": "Fix or remove the broken markdown link",
        "nav.resource.missing": "Run 'knowledge.py bootstrap' to create missing resources",
        "nav.wiki.missing": "Run 'knowledge.py bootstrap' to create missing wiki files",
        "nav.stale": "Run 'knowledge.py refresh' to regenerate nav tables",
    }.get(finding_id, "")


# ---------------------------------------------------------------------------
# Main entry point
# ---------------------------------------------------------------------------

def main():
    # Emit UTF-8 regardless of the host console code page (Windows consoles
    # default to cp1252/cp437 and would mangle em-dashes in reports).
    for stream in (sys.stdout, sys.stderr):
        try:
            stream.reconfigure(encoding="utf-8")
        except (AttributeError, ValueError):
            pass

    parser = argparse.ArgumentParser(
        prog="knowledge.py",
        description="tome — deterministic knowledge-layer tool",
    )
    subparsers = parser.add_subparsers(dest="subcommand", required=True)

    # bootstrap
    subparsers.add_parser("bootstrap", help="Scaffold wiki/ and navigate skill supporting files")

    # refresh
    subparsers.add_parser("refresh", help="Refresh status:generated files; report stale knowledge")

    # context
    ctx_parser = subparsers.add_parser("context", help="Resolve navigation context for a path")
    ctx_parser.add_argument("path", help="Target path (repo-relative or absolute)")
    ctx_parser.add_argument("--json", action="store_true", help="Output as JSON")

    # check
    chk_parser = subparsers.add_parser("check", help="Validate knowledge-layer health")
    chk_parser.add_argument("--json", action="store_true", help="Output as JSON")

    # impact
    imp_parser = subparsers.add_parser("impact", help="Analyze wiki impact of changed source paths")
    imp_parser.add_argument("paths", nargs="*", help="Changed file paths (or pipe via stdin)")

    args = parser.parse_args()

    root = find_repo_root()

    if args.subcommand == "bootstrap":
        sys.exit(cmd_bootstrap(root))
    elif args.subcommand == "refresh":
        sys.exit(cmd_refresh(root))
    elif args.subcommand == "context":
        sys.exit(cmd_context(root, args.path, getattr(args, "json", False)))
    elif args.subcommand == "check":
        sys.exit(cmd_check(root, getattr(args, "json", False)))
    elif args.subcommand == "impact":
        # Accept paths from positional args or stdin
        paths = args.paths if args.paths else []
        if not paths and not sys.stdin.isatty():
            paths = [line for line in sys.stdin.read().splitlines() if line.strip()]
        sys.exit(cmd_impact(root, paths))
    else:
        parser.print_help()
        sys.exit(EXIT_USAGE)


if __name__ == "__main__":
    main()