feat(docs): add manual-section CLASSIFICATION tag, wire it into the build

A function with a dedicated manual section (docs/manual/16-agent-tooling.md,
so far) now carries manual-section(<slug>) in its own CLASSIFICATION line
instead of relying on a NOTES pointer nobody can grep for. Applied to
agents-init and agents-vault, both pointing at 16-agent-tooling.

docs/build-manual.py: _resolve_manual_section reads the target page's own
manTitle/title fresh at build time rather than duplicating a section
number into the tag, so a renumbered section (like this one, twice
already) never requires touching the tag -- only the slug (the filename)
does, and only if the page itself is renamed. render_entry and
render_entry_site both gained an optional root parameter and now emit a
'See also' line (plain text + relative path for the man page, a real
markdown link on the site) whenever the tag resolves; omitted silently
when it doesn't (a build isn't the place to fail on a bad slug).

docs/verify-manual.py: unit tests for the new resolver and both renderers,
plus a real-data scan (test_real_manual_section_tags_resolve) that fails
the suite if any function's manual-section(<slug>) tag points nowhere --
the actual enforcement half of the convention, since the build stays
silent about it.

docs/function-classification-schema.md, CONTRIBUTING.md: documents the
tag, and widens CLASSIFICATION's own framing from strictly hazard/shadow
tags to general-purpose (the user's call, not mine to make unilaterally --
scope-broadening an existing convention). The 'Dedicated manual sections'
subsection (added earlier this branch) now names the tag as the
machine-checked half of that convention, with NOTES demoted to a
nice-to-have for a header-only reader.

CONTRIBUTING.md

@@ -391,7 +391,7 @@ all optional except where noted:
 | `CATEGORY` | **Required to appear in the manual at all** — see below. |
 | `COMPONENT` | Only for functions gated by the [opinionated-component system](#opinionated-components). |
 | `DEPENDENCIES` | Other functions, and external CLI tools, this one needs for full functionality — required or optional-with-fallback alike. |
-| `CLASSIFICATION` | Hazard/shadow-interaction tags — see below. |
+| `CLASSIFICATION` | Hazard/shadow-interaction tags, plus a couple of general-purpose ones (`manual-section`) — see below. |
 | `SYNOPSIS` | One-line usage form. |
 | `DESCRIPTION` | Prose description; can span multiple paragraphs. |
 | `ARGUMENTS` | Flags/positional args, one per line. |
@@ -447,13 +447,17 @@ If your function genuinely doesn't fit any of these, add a new
 `docs/manual/05-functions/NN-your-category.md` stub (with frontmatter
 matching its siblings) rather than force-fitting it into an existing one.
 
-**`CLASSIFICATION` flags hazards and shadow interactions, optional and
-omitted when nothing applies:** whether the function calls a
+**`CLASSIFICATION` is the general-purpose tag field, optional and omitted
+when nothing applies:** mostly hazards and shadow interactions — whether
+the function calls a
 [C1-shadowed command](docs/manual/08-components-reference/01-c1-command-shadows.md)
 bare wanting the override (`uses-shadow(ls)`) or bypasses it deliberately
 via `command`/`builtin` (`bypasses-shadow(cat)`), and general hazards —
-`destructive`, `network`, `blocking-prompt`. Full tag definitions and
-placement rule: [`docs/function-classification-schema.md`](docs/function-classification-schema.md).
+`destructive`, `network`, `blocking-prompt` — but not exclusively: a
+function with its own dedicated manual section (below) carries
+`manual-section(<slug>)` here too, so that fact is grep-able without
+reading every `NOTES` field. Full tag definitions and placement rule:
+[`docs/function-classification-schema.md`](docs/function-classification-schema.md).
 
 ### Dedicated manual sections for complex subsystems
 
@@ -470,15 +474,24 @@ subsystem its own numbered top-level section under `docs/manual/`
 stay short and point there for the full picture, the same way this
 document points at other reference files rather than repeating them.
 
+A function with a dedicated section carries `manual-section(<slug>)` in
+its own `# CLASSIFICATION` (see `functions/agents-init.fish`; full tag
+definition in
+[`docs/function-classification-schema.md`](docs/function-classification-schema.md))
+— that's what makes the section discoverable without reading every
+function's `NOTES` by hand, and it's what `docs/build-manual.py` reads to
+render the "See also" line on the function's generated entry.
+`docs/verify-manual.py` fails the build if the slug doesn't resolve to a
+real page, so a typo or a renamed file can't go unnoticed — but it cannot
+check the *content* is current. A `# NOTES` line pointing at the same page
+(see the existing example) is worth adding too, for a reader who only
+reads the header text rather than the generated docs, but the tag is the
+part something else actually verifies.
+
 This is a genuine exception to "the doc-header is the single source of
-truth" above, and it comes with an obligation `verify-manual.py` cannot
-enforce for you: nothing checks that a dedicated section still describes
-the function's *current* behavior. **Whenever you change what one of
-these functions does, update its dedicated section in the same commit or
-pull request** — not as a follow-up. A function with a dedicated section
-should say so in its own `# NOTES` (see `functions/agents-init.fish` for
-the pattern), so a later reader of just the header still finds the fuller
-page.
+truth" above. **Whenever you change what one of these functions does,
+update its dedicated section in the same commit or pull request** — not
+as a follow-up.
 
 ### Private/internal helper functions
 

docs/build-manual.py

@@ -202,7 +202,7 @@ def build_concat(root: Path) -> str:
     Only bodies are passed: the pandoc metadata block above is not prose
     and must survive byte-for-byte.
     """
-    entries = build_entries(mt.parse_functions(FUNCTIONS))
+    entries = build_entries(mt.parse_functions(FUNCTIONS), root=root)
     chunks: list[str] = []
     pandoc_path = root / "_pandoc.yml"
     if pandoc_path.exists():
@@ -726,7 +726,44 @@ def _classification_tags(raw: list[str]) -> list[str]:
     return [t for t in tags if t]
 
 
-def render_entry(fn: dict[str, list[str]], used_by: list[str], link=None) -> str:
+MANUAL_SECTION_RE = re.compile(r"^manual-section\(([\w./-]+)\)$")
+
+
+def _manual_section_slug(tags: list[str]) -> str | None:
+    """Pull the slug out of a `manual-section(<slug>)` CLASSIFICATION tag, if present."""
+    for tag in tags:
+        m = MANUAL_SECTION_RE.match(tag)
+        if m:
+            return m.group(1)
+    return None
+
+
+def _resolve_manual_section(root: Path | None, slug: str) -> tuple[str, str, str] | None:
+    """Resolve a manual-section(<slug>) tag to (display label, site link, doc-relative path).
+
+    Looks for <slug>.md (a top-level single-file section) or <slug>/index.md
+    (a directory-based section), matching the two shapes docs/manual/
+    actually uses. The display label is read fresh from the target's own
+    frontmatter (manTitle, falling back to title) rather than duplicated in
+    the tag, so a renumbered section never needs its tag updated -- only
+    the slug (the filename) does, and that only changes if the page itself
+    is renamed. Returns None -- silently, this is a build, not a check;
+    verify-manual.py is where a dangling slug is a real failure -- when
+    <root> is unset or neither candidate exists.
+    """
+    if root is None:
+        return None
+    for relpath in (f"{slug}.md", f"{slug}/index.md"):
+        if (root / relpath).exists():
+            fm, _ = mt.parse(root / relpath)
+            label = fm.get("manTitle") or fm.get("title", slug)
+            return label, f"/{slug}/", relpath
+    return None
+
+
+def render_entry(
+    fn: dict[str, list[str]], used_by: list[str], link=None, root: Path | None = None
+) -> str:
     """Render one parsed function header as a manual entry body.
 
     Emits the same man-page shape Section 5 was authored in — one 4-space
@@ -759,15 +796,22 @@ def render_entry(fn: dict[str, list[str]], used_by: list[str], link=None) -> str
     def names(raw: list[str]) -> list[str]:
         return [n for n in re.split(r"[,\s]+", " ".join(raw)) if n]
 
+    classification = _classification_tags(fn.get("CLASSIFICATION", []))
     refs = []
     for label, values in (
         ("Dependencies", names(fn.get("DEPENDENCIES", []))),
-        ("Classification", _classification_tags(fn.get("CLASSIFICATION", []))),
+        ("Classification", classification),
         ("Used by", sorted(used_by)),
     ):
         if values:
             rendered = ", ".join(link(v) if link else f"`{v}`" for v in values)
             refs.append(f"**{label}:** {rendered}")
+    slug = _manual_section_slug(classification)
+    if slug:
+        resolved = _resolve_manual_section(root, slug)
+        if resolved:
+            label, _href, relpath = resolved
+            refs.append(f"**See also:** {label} (`docs/manual/{relpath}`)")
     if refs:
         block += "\n\n" + "\n\n".join(refs)
     return block
@@ -871,7 +915,9 @@ SITE_SECTIONS = (
 )
 
 
-def render_entry_site(fn: dict[str, list[str]], used_by: list[str], link=None) -> str:
+def render_entry_site(
+    fn: dict[str, list[str]], used_by: list[str], link=None, root: Path | None = None
+) -> str:
     """Render one parsed function header as a manual entry body for the site.
 
     Unlike `render_entry` (the single indented man-page block pandoc wants,
@@ -905,15 +951,22 @@ def render_entry_site(fn: dict[str, list[str]], used_by: list[str], link=None) -
     def names(raw: list[str]) -> list[str]:
         return [n for n in re.split(r"[,\s]+", " ".join(raw)) if n]
 
+    classification = _classification_tags(fn.get("CLASSIFICATION", []))
     refs = []
     for label, values in (
         ("Dependencies", names(fn.get("DEPENDENCIES", []))),
-        ("Classification", _classification_tags(fn.get("CLASSIFICATION", []))),
+        ("Classification", classification),
         ("Used by", sorted(used_by)),
     ):
         if values:
             rendered = ", ".join(link(v) if link else f"`{v}`" for v in values)
             refs.append(f"**{label}:** {rendered}")
+    slug = _manual_section_slug(classification)
+    if slug:
+        resolved = _resolve_manual_section(root, slug)
+        if resolved:
+            label, href, _relpath = resolved
+            refs.append(f"**See also:** [{label}]({href})")
     if refs:
         parts.append("\n\n".join(refs))
 
@@ -921,7 +974,7 @@ def render_entry_site(fn: dict[str, list[str]], used_by: list[str], link=None) -
 
 
 def build_entries(
-    functions: dict[str, dict], link=None, site: bool = False
+    functions: dict[str, dict], link=None, site: bool = False, root: Path | None = None
 ) -> dict[str, list[tuple[str, str]]]:
     """Group rendered entries by category stem, ordered by function name.
 
@@ -929,6 +982,9 @@ def build_entries(
     authored: a bidirectional link maintained by hand drifts the moment one
     side is edited. `site` selects `render_entry_site` (headings + tables)
     over `render_entry` (the man-page indented block `build_concat` needs).
+    `root` (docs/manual/) resolves any `manual-section(<slug>)`
+    CLASSIFICATION tag to that page's own title -- omitted, the default,
+    an entry with the tag just gets no "See also" line rather than failing.
     """
     used_by: dict[str, list[str]] = {}
     for name, fn in functions.items():
@@ -940,7 +996,7 @@ def build_entries(
     out: dict[str, list[tuple[str, str]]] = {}
     for name in sorted(functions):
         fn = functions[name]
-        body = render(fn, used_by.get(name, []), link)
+        body = render(fn, used_by.get(name, []), link, root=root)
         out.setdefault(fn["CATEGORY"][0], []).append((name, body))
     return out
 
@@ -1041,7 +1097,9 @@ def build_site(root: Path, out: Path) -> list[dict]:
     out.mkdir(parents=True)
 
     functions = mt.parse_functions(FUNCTIONS)
-    entries = build_entries(functions, link=lambda n: _entry_link(n, functions), site=True)
+    entries = build_entries(
+        functions, link=lambda n: _entry_link(n, functions), site=True, root=root
+    )
 
     sidebar: list[dict] = [{"label": "Home", "link": "/"}]
     standard_groups: dict = {}

docs/function-classification-schema.md

@@ -5,6 +5,14 @@ doc-header label. It's referenced from code comments and commit messages —
 link here, not to anything under `AGENTS/` (that tree is git-ignored local
 agent state, not part of the repo).
 
+`CLASSIFICATION` isn't limited to command-safety hazards, even though most
+of the closed set below is exactly that — it's the general-purpose place to
+tag what a function touches or how it behaves, whenever that's worth
+surfacing without reading the function's own body. `manual-section(<slug>)`
+is the one tag in the set that isn't a hazard at all: it marks a function
+that has its own dedicated manual section beyond this header (see
+[Dedicated manual sections for complex subsystems](../CONTRIBUTING.md#dedicated-manual-sections-for-complex-subsystems)).
+
 See [Public function documentation header](../CONTRIBUTING.md#public-function-documentation-header)
 in `CONTRIBUTING.md` for where `CLASSIFICATION` fits among the other header
 labels, and [C1 — Command Shadows](manual/08-components-reference/01-c1-command-shadows.md)
@@ -72,6 +80,22 @@ it empty as a placeholder.
   handler, an fzf-driven picker) — the hazard this tag exists for is a
   script or another function calling it unexpectedly, not a human running
   it themselves.
+- **`manual-section(<slug>)`** — this function has a dedicated manual
+  section beyond its own header; `<slug>` is that page's filename under
+  `docs/manual/` with the extension dropped (`16-agent-tooling` for
+  `docs/manual/16-agent-tooling.md`; a directory-based section like
+  `08-components-reference` uses its directory name the same way, resolved
+  against its `index.md`). `docs/build-manual.py` reads the target page's
+  own `manTitle`/`title` at build time and renders a **See also** line on
+  the function's generated entry — the tag only needs to keep pointing at
+  the right *file*; the displayed section number is never duplicated into
+  the tag, so it can't go stale on its own if the manual gets renumbered.
+  `docs/verify-manual.py` fails if the slug doesn't resolve to a real page.
+  Multiple functions may carry the same slug (`agents-init` and
+  `agents-vault` both point at `16-agent-tooling`, one section covering
+  both). See [Dedicated manual sections for complex subsystems](../CONTRIBUTING.md#dedicated-manual-sections-for-complex-subsystems)
+  in `CONTRIBUTING.md` for when a function's behavior has outgrown its
+  header and belongs in one of these instead.
 
 ## Placement
 

docs/verify-manual.py

@@ -1674,6 +1674,117 @@ def test_concat_section_five_stays_verbatim():
     assert not offenders, f"backticks inside verbatim entries: {offenders[:3]}"
 
 
+def test_manual_section_slug_extracts_tag():
+    """`manual-section(<slug>)` is found among other CLASSIFICATION tags, or not at all."""
+    import build_manual
+
+    assert build_manual._manual_section_slug(["destructive", "manual-section(foo-bar)"]) == "foo-bar"
+    assert build_manual._manual_section_slug(["network"]) is None
+    assert build_manual._manual_section_slug([]) is None
+
+
+def test_resolve_manual_section_reads_target_frontmatter():
+    """Resolves both page shapes (top-level file, directory index) and reports None cleanly."""
+    import build_manual
+
+    with tempfile.TemporaryDirectory() as d:
+        root = Path(d)
+        (root / "solo.md").write_text(
+            "---\ntitle: Solo\nmanTitle: 9. SOLO\n---\nbody\n"
+        )
+        (root / "grouped").mkdir()
+        (root / "grouped" / "index.md").write_text(
+            "---\ntitle: Grouped\nmanTitle: 10. GROUPED\n---\nbody\n"
+        )
+
+        label, href, relpath = build_manual._resolve_manual_section(root, "solo")
+        assert label == "9. SOLO", label
+        assert href == "/solo/", href
+        assert relpath == "solo.md", relpath
+
+        label, href, relpath = build_manual._resolve_manual_section(root, "grouped")
+        assert label == "10. GROUPED", label
+        assert href == "/grouped/", href
+        assert relpath == "grouped/index.md", relpath
+
+        assert build_manual._resolve_manual_section(root, "missing") is None
+        assert build_manual._resolve_manual_section(None, "solo") is None
+
+
+def test_render_entry_see_also_appears_only_when_root_resolves():
+    """The man-page See-also line needs both the tag and a root that resolves it."""
+    import build_manual
+
+    fn = {
+        "SYNOPSIS": ["thing"],
+        "DESCRIPTION": ["Does a thing."],
+        "CLASSIFICATION": ["manual-section(deep-dive)"],
+    }
+
+    with tempfile.TemporaryDirectory() as d:
+        root = Path(d)
+        (root / "deep-dive.md").write_text(
+            "---\ntitle: Deep Dive\nmanTitle: 20. DEEP DIVE\n---\nbody\n"
+        )
+
+        out = build_manual.render_entry(fn, [], root=root)
+        assert "**See also:** 20. DEEP DIVE (`docs/manual/deep-dive.md`)" in out, out
+
+        # No root at all -- same as every other existing caller that never
+        # passes one -- silently omits the line rather than raising.
+        out_no_root = build_manual.render_entry(fn, [])
+        assert "See also" not in out_no_root, out_no_root
+
+        # A root that exists but doesn't have the target page: also silent.
+        with tempfile.TemporaryDirectory() as empty:
+            out_missing = build_manual.render_entry(fn, [], root=Path(empty))
+            assert "See also" not in out_missing, out_missing
+
+
+def test_render_entry_site_see_also_is_a_real_link():
+    """The site's See-also line is a markdown link to the resolved page's site path."""
+    import build_manual
+
+    fn = {
+        "SYNOPSIS": ["thing"],
+        "DESCRIPTION": ["Does a thing."],
+        "CLASSIFICATION": ["manual-section(deep-dive)"],
+    }
+
+    with tempfile.TemporaryDirectory() as d:
+        root = Path(d)
+        (root / "deep-dive.md").write_text(
+            "---\ntitle: Deep Dive\nmanTitle: 20. DEEP DIVE\n---\nbody\n"
+        )
+        out = build_manual.render_entry_site(fn, [], root=root)
+        assert "**See also:** [20. DEEP DIVE](/deep-dive/)" in out, out
+
+
+def test_real_manual_section_tags_resolve():
+    """Every manual-section(<slug>) tag on a real function points at a real page.
+
+    This is the enforcement half of the convention: build-manual.py stays
+    silent about a dangling slug (it just skips the See-also line), so this
+    is the only thing that turns a typo'd or stale slug into a failure.
+    """
+    import build_manual
+
+    functions = mt.parse_functions(build_manual.FUNCTIONS)
+    checked = 0
+    for name, fn in functions.items():
+        tags = build_manual._classification_tags(fn.get("CLASSIFICATION", []))
+        slug = build_manual._manual_section_slug(tags)
+        if slug is None:
+            continue
+        checked += 1
+        resolved = build_manual._resolve_manual_section(build_manual.MANUAL, slug)
+        assert resolved is not None, (
+            f"{name}'s manual-section({slug}) tag doesn't resolve to "
+            f"docs/manual/{slug}.md or docs/manual/{slug}/index.md"
+        )
+    assert checked > 0, "expected at least one real function to carry manual-section(...)"
+
+
 TESTS = [v for k, v in sorted(globals().items()) if k.startswith("test_")]
 
 

functions/agents-init.fish

@@ -8,7 +8,7 @@
 #   _agents_init_sync_instructions, _agents_repo_install_tools, _agents_repo_sync, _agents_init_ensure_gitignore
 #
 # CLASSIFICATION
-#   self-limiting(rm,mkdir,grep), bypasses-shadow(mv)
+#   self-limiting(rm,mkdir,grep), bypasses-shadow(mv), manual-section(16-agent-tooling)
 #
 # SYNOPSIS
 #   agents-init [-a | --agents] [-p | --plugins] [-v | --verbose]

functions/agents-vault.fish

@@ -10,7 +10,7 @@
 #   _agents_repo_install_tools, git, hostname
 #
 # CLASSIFICATION
-#   self-limiting(rm,mkdir)
+#   self-limiting(rm,mkdir), manual-section(16-agent-tooling)
 #
 # SYNOPSIS
 #   agents-vault [--link] [--push] [--restore] [--status]