#1133 Reject an anchor link that names no heading - #1135

Rulebook, skill, and subagent bodies are checked for anchor-only link targets before any rewriting, so an anchor naming no heading (or more than one) in the same body fails the run instead of shipping as a dead locator. `sync` inherits the check through its three pre-write render gates, which means a dry run reports it with nothing written.

Each renderer validates its include-expanded text, so an anchor authored in a partial is resolved against the artifact that inlines it. Validating ahead of the rewrite also keeps a heading carrying a `{tool:NAME}` token unaddressable, which it must be: its slug differs per harness, so no single fragment reaches it.

The harness guidance files `install` renders and the shared guidance files it copies are checked for anchor-only link targets that name no heading, so the delivery path with no render gate of its own no longer ships a dead in-body locator.

Both checks run above the dry-run gate, so a preview reports the failure with nothing written. Harness guidance is checked on its include-expanded text, where the render already holds it. Shared guidance ships verbatim, so its check reads the source, and it applies in link mode too: a symlink carries the same dead locator a copy would.

…ution suite

`content-link-resolution.test.ts` derives heading slugs and blanks non-declaring regions through `anchor-resolution` instead of its own copies, so the repo-wide suite and the render-pass gate cannot disagree about what an anchor resolves to. Blanking now covers frontmatter as well as fenced blocks.

The suite keeps its full scope. It reports every violation across the tree at once where the gate throws on the first artifact, and a fragment on a cross-file target is checked nowhere else.

The specification states that an anchor-only link must name exactly one heading in its own body, across rulebooks, skills, subagents, and the guidance files `install` ships, and moves that rule from the test-enforced class to the run-failing one.

It also records what the rule exempts and what it forbids: frontmatter and fenced code blocks count on neither side, an anchor authored in a partial is reported against the artifact that inlines it, and a heading carrying a token cannot be anchored, since its slug differs per harness.

…tal error

A regular `.md` sitting directly under `content/skills/` no longer aborts `install`. The skill-directory probe stats `<entry>/SKILL.md` and read only ENOENT as "not a skill", so a file there raised ENOTDIR and propagated; `isMissingFile` covers both codes and is documented for this exact probe.

With the probe fixed, `installSkillEntry`'s single-file branch is reachable from its caller, so it gains the same anchor check the directory branch runs.

Four shapes of valid Markdown no longer fail the gate. A link target carrying a Markdown link title resolves on its fragment alone. A tilde-delimited fence is blanked alongside a backtick one, and a fence now closes only on a marker of its own character and at least its length. A link inside an inline code span is read as an illustration rather than a request.

A body opening on a thematic break keeps its headings. Frontmatter is recognized by a top-level YAML key between the delimiters rather than by the delimiters alone; a YAML comment cannot serve as the discriminator, since `# Text` is also an ATX heading.

Inline code spans are blanked on the link-scanning side only. A span inside a heading contributes to that heading's slug, which the slugifier reaches by stripping backticks as punctuation, so blanking it there would break every anchor into a heading that names a symbol.

An indented code block stays scanned: telling one from a nested list item takes block-level parsing, and a wrong call would blank a real anchor. The specification records that boundary along with the widened exemptions.

The failure hint now offers an inlined partial as a lead rather than asserting one, and the helper's contract and the specification both name the paths that expand includes. A rulebook body and a shared guidance file are checked as authored, so neither can have a partial behind its error.

…he rest

A fence with no closing run stops the anchor gate for the remainder of the body, and it now fails the run rather than reporting a clean pass. Everything below an open fence reads as code, so no anchor there can be checked, and a silent pass over an unchecked remainder is indistinguishable from a checked one.

The route is a closing run shorter than its opening: a four-backtick fence wrapping a three-backtick example is closed only by four, so the typo lands in exactly the case run-length matching makes expressible.

The fence walk moves into `scanFences`, which returns the blanked lines and the opening run of any fence left open, so the assertion and `normalizeForAnchorScan` share one state machine.

The specification records the failure, and adds the case its exemption sentence left an author to guess at: a code span within a heading is part of that heading's text, so the heading still anchors with its backticks dropped as punctuation.

`content-link-resolution.test.ts` reports a host that leaves a code fence open instead of scanning the blanked remainder and passing. It is the only anchor coverage this repo runs over library artifacts it does not itself deploy, so a dead anchor hidden under an open fence would have reached a consumer's `sync` with nothing failing here first.

`findUnterminatedFence` exposes the verdict `scanFences` already computes, which `normalizeForAnchorScan` discards. The suite reports the fence and moves on to the next host, matching the order the render gate uses: once a fence is open to end of file, the anchors the host appears to carry are not the ones it carries.

The specification's enumeration of run-failing checks lists the fence condition as its own item rather than a parenthetical inside the anchor one.

Installing shared guidance dispatches each file to a dedicated `installSharedGuidanceEntry`, mirroring how support-directory installs dispatch to `installSkillEntry`, and brings `installSharedGuidance` back within the complexity ceiling the lint suite enforces.

The per-file function reports whether the install reached disk, so the manifest's recorded install time holds its previous value when a dry run or a skipped user-modified file writes nothing.