fix(gates): check body-level routing targets, not just descriptions

The ADR-0020 boundary resolver (boundary_targets()/unresolved_targets())
only ever read a SKILL.md's description. A target named in the BODY -- a
dispatch table row, a "run X" step, both routine in a 900-word procedure
-- was checked by nothing. Two real instances shipped before either was
caught by reading rather than by a gate: bin/write-docs routed twice to a
deleted `to-prd` skill, and bin/triage told an agent to run a nonexistent
`/setup-matt-pocock-skills` (both fixed in 03abcff; that fix was the
symptom, this gate is the actual ask per #124).

Added a separate, narrower extractor -- body_targets() /
unresolved_body_targets() in the shared lib-boundary-resolver.sh -- rather
than reusing the description resolver at wider scope. The description
gate's sentence-level heuristics (BOUNDARY_MARKER, the follower test,
in-sentence corroboration) are tuned for a one-to-three-sentence routing
clause and misfire on dispatch-table/procedure prose in both directions,
so the body gate reads only explicit route notation (`/name`,
backticked-or-slash-prefixed `-> name` / `-> name`), already the
description gate's own unconditionally-blocking tier.

Three guards were added after running the extractor over the real
39-skill corpus and reading every hit rather than assuming the design was
correct:

- a target must be hyphenated, even in notation -- single-word citations
  like `/fork` (forge, citing Claude Code's own /fork command) and
  `/name` (skill-author, a placeholder) are not routes.
- a bare hyphenated word after any arrow is not notation -- only
  ARROW_MARKED (backticked/slash-prefixed) is used, not NOTATION_ARROW's
  bare form, so ordinary process-chain prose ("prop -> new ref ->
  re-render", caveman) is not read as a route.
- a name immediately preceded by `<` is a closing tag
  (`</what-to-do>`, grill-with-docs), not /name notation.

Wired into both consumers that must agree by contract: scripts/
skill-size-check.sh (the pre-commit hook) and factory-audit's
lib-checks-skill.sh (the audit). Verified identical findings across both
over the whole corpus.

tests/test-adr0020-targets.sh gains a dedicated section pinning the two
live true positives and all three guards. docs/spec/gates.md and
ADR-0020 get a matching amendment.

Fixes: #124
ADR: 0020

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EGHFJextYtVQseaHPDDhxB

docs/spec/gates.md

@@ -360,6 +360,68 @@ at a real sentence end. **Read the second bullet forward as well as back:** a ba
 after a dotted filename is now extracted, resolved, and a blocking ERROR when it dangles, where the
 same clause used to pass unchecked in silence.
 
+### Body-level routing targets (issue #124)
+
+Everything above resolves targets named in the **description** — the one field `boundary_targets()`
+and `unresolved_targets()` read. Until issue #124, a target named in the **body** — a dispatch table
+or a "run X" step, both routine in a 900-word procedure — was checked by nothing: `bin/write-docs`
+routed twice to a deleted `to-prd` skill and `bin/triage` told an agent to run a nonexistent
+`/setup-matt-pocock-skills`, and both were found by reading, not by any gate (fixed in `03abcff`;
+the gate itself is the ask this section documents).
+
+`body_targets()` / `unresolved_body_targets()` (`lib-boundary-resolver.sh`) are a **separate,
+narrower** extractor, not a reuse of the description one at wider scope. A body is dispatch-table
+and procedure prose, not a one-to-three-sentence routing clause, so `BOUNDARY_MARKER`, the follower
+test and in-sentence corroboration all misfire on it in both directions — under-firing on a table
+row that carries no "do not"/"instead", over-firing on a procedure step that names a file, a CLI verb
+or a config key exactly the way a route names a skill. So the body gate reads only **notation**,
+already the description gate's own "always blocks" tier, and nothing softer:
+
+| Form | Pattern | Requires |
+|---|---|---|
+| `/name` | `NOTATION_SLASH` | a hyphen in `name`; not preceded by `<` |
+| `-> name` / `→ name` | `ARROW_MARKED` | the name **backticked or slash-prefixed** — `NOTATION_ARROW`'s bare form is not used here |
+
+Both constraints exist because the corpus, not intuition, said so — each is a real false positive
+this gate produced once and was narrowed to remove:
+
+- **No SUGGESTION tier, no continuation, one arrow per target.** Both forms are notation, and
+  notation is unconditionally blocking — there is no ambiguous prose reading left to soften, so
+  there is nothing to report at a softer tier. `CONT_MARKED`/`CONT_ANY` are not run either, so
+  `-> \`a\` or \`b\`` resolves only `a`, same as the one-arrow-one-target convention **#107** already
+  states for descriptions — enforced here by construction instead of by a second SUGGESTION.
+- **A bare hyphenated word after any arrow is not notation here.** `NOTATION_ARROW` (used for the
+  description gate's own `Not X -> name` sweep) matches a bare `-> name` unconditionally, and a body
+  is full of ordinary arrow prose that is not a route: `caveman`'s own `Inline obj prop -> new ref ->
+  re-render.` read as a dangling route to `re-render` under that pattern. `ARROW_MARKED` requires the
+  target to be backticked or slash-prefixed, which the one real historical target (`` -> `to-prd` ``,
+  per `03abcff`'s diff) already was, so the narrowing costs no real coverage.
+- **A single-word target is discarded, even in notation.** `` `/fork` `` (`forge/SKILL.md`,
+  contrasting `context: fork` with Claude Code's own `/fork` subagent command) and `` `/name` ``
+  (`skill-author/SKILL.md`, "the user types `/name`" — a placeholder for the skill's *own* name, not
+  a route) are both real corpus citations of a tool or a placeholder, not routes, and both hard-FAILed
+  with no escape hatch before the hyphen requirement was added. This is a real, accepted recall loss:
+  a body dispatch entry to a genuinely single-word skill (`forge`, `research`, `triage`, `tdd`,
+  `prototype`) cannot be checked through this extractor. Same trade the description gate already
+  makes for the *bare* form (the known gap above), extended here to notation as well because the body
+  genre has no boundary-sentence signal to lean on instead.
+- **A name immediately preceded by `<` is a closing tag, not a route.** `grill-with-docs/SKILL.md`
+  uses XML-style prompt delimiters (`<what-to-do>...</what-to-do>`, `<supporting-info>...`), and
+  `</what-to-do>` is indistinguishable from `/what-to-do` notation by every other rule above. No route
+  is ever written directly after `<` in this corpus, so the guard costs nothing else.
+
+Fenced code blocks are masked first (`mask_fenced()`, the same masking `gotcha_stats()` and the
+references/-pointer check already use): an illustrative ` ```/some-skill``` ` in `skill-author` or
+`factory-audit` — which document this very notation — is not a live dispatch entry.
+
+Both consumers agree by construction: `scripts/skill-size-check.sh` and
+`factory-audit/scripts/lib-checks-skill.sh` each call `body_targets()`/`unresolved_body_targets()`
+independently, over the same `known_targets()` universe the description check already computed, so
+the "DID NOT RUN" INFO tier covers both description and body targets in one message rather than
+firing twice. `tests/test-adr0020-targets.sh`'s "body-level routing targets (issue #124)" section
+pins both the two live true positives and every guard above; the corpus-wide dangling assertion
+(`EXPECTED_DANGLING`) covers body targets the same way it already covered description ones.
+
 ### SUGGESTION-only checks
 
 Deterministic to measure, judgment to act on: