feat(ledger): the consumer map reads transition names and concatenated prefixes (#2970)

Paying down #2962 measured `flag="unused-css"` against a hand audit and
found it had a permanent false-positive floor: roughly sixty classes it
called unused are alive and always would be, because two ordinary authoring
forms produce names no reader of `class=` attributes can see. A flag whose
list you cannot act on line by line is worse than no flag — act on it and
you delete live UI.

- A transition `name=` IS a class reference. `<Transition name="toast">`
  makes Vue apply `.toast-enter-active` and its siblings at runtime, and
  React's `<CSSTransition classNames="fade">` does the same with a different
  suffix set. Every spelling of the tag is read (`Transition`,
  `TransitionGroup`, `transition-group`), and the emitted suffix set is the
  union of Vue 3, Vue 2 and React: naming a class no rule defines costs
  nothing, since it resolves to no row. A bound `:name` stays unknowable.
- A concatenated name contributes its static head as a PREFIX reference.
  `` `status-${s}` ``, `'pri-' + p` and `class="card-{{ v }}"` all leave a
  head behind once the hole is blanked — and `_CLASS_TOKEN_RE` accepts a
  trailing hyphen, so until now the extractor emitted a junk token
  `"status-"` that matched nothing. It is now `status-*`, and
  resolve_consumers credits every row whose symbol starts with that head,
  each under the same own-file-else-fan-out rule as an exact token. `*`
  cannot occur in a class token, so the marker rides the existing
  dict[str, int] with no schema change. A head shorter than two characters
  says nothing and is dropped.

Crediting every candidate row is the honest reading: the template genuinely
does not say which one it built, and the alternative is reporting live rules
as dead. What the map still cannot see is a name assembled in a script —
`classList.add` — which stays deliberately out of scope; the skill, the
`flag=` docstring and the refresh payload docs all say so now.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scribe/services/coverage.py

@@ -294,6 +294,34 @@ _DYNAMIC_CLASS_RE = re.compile(
 )
 # Svelte's directive form: class:active={cond}.
 _SVELTE_CLASS_RE = re.compile(r"(?<![:\w.-])class:([A-Za-z_][A-Za-z0-9_-]*)\s*=")
+# Transition classes are applied by the FRAMEWORK, never written in markup:
+# <Transition name="toast"> makes Vue add .toast-enter-active et al at
+# runtime, and React's <CSSTransition classNames="fade"> does the same. A
+# reader of `class=` attributes alone therefore calls every one of those
+# rules unused, which is a false positive no amount of care in the
+# stylesheet can avoid (#2970). A dynamic `:name="…"` stays unknowable.
+_TRANSITION_NAME_RE = re.compile(
+    r"""<\s*[Tt]ransition(?:-[Gg]roup|Group)?\b[^>]*?(?<![:\w.-])name\s*=\s*"""
+    r"""(?:"([^"]*)"|'([^']*)')"""
+    r"""|(?<![:\w.-])classNames\s*=\s*(?:"([^"]*)"|'([^']*)')"""
+)
+# The union of what Vue 3, Vue 2 and React CSSTransition generate. Naming a
+# class that no rule defines costs nothing — it resolves to no row — so the
+# union is safer than guessing the framework from the file.
+_TRANSITION_SUFFIXES = (
+    "-enter", "-enter-from", "-enter-active", "-enter-to", "-enter-done",
+    "-leave", "-leave-from", "-leave-active", "-leave-to",
+    "-exit", "-exit-active", "-exit-done",
+    "-appear", "-appear-from", "-appear-active", "-appear-to", "-appear-done",
+    "-move",
+)
+# A name built by concatenation — `status-${s}`, 'pri-' + p, class="c-{{ v }}"
+# — leaves its static head behind once the hole is blanked. That head is a
+# PREFIX reference, spelled `status-*`: "*" cannot occur in a class token, so
+# the marker rides the plain token dict without a schema change. Needs a real
+# name before the separator; `a-` or a bare `-` says nothing worth matching.
+_PREFIX_MIN_STEM = 2
+PREFIX_MARK = "*"
 # Inside a dynamic expression: string literals (ternary arms, array items,
 # quoted object keys) and the bare keys of object literals.
 _STR_LIT_RE = re.compile(r"""'([^'\\]*)'|"([^"\\]*)"|`([^`]*)`""")
@@ -307,8 +335,20 @@ _MUSTACHE_RE = re.compile(r"\{[{%][^}]*[}%]\}")
 
 def _class_tokens(value: str) -> list[str]:
     """The class tokens of a static attribute value: whitespace-split, only
-    well-formed names (an interpolation like `{{ cls }}` contributes none)."""
-    return [t for t in _MUSTACHE_RE.sub(" ", value).split() if _CLASS_TOKEN_RE.match(t)]
+    well-formed names. An interpolation (`{{ cls }}`, `${cls}`) is blanked
+    before the split, so a name built around one leaves its static head —
+    `status-` from `status-{{ s }}` — which is emitted as the prefix
+    reference `status-*` rather than as a class nothing is called."""
+    out: list[str] = []
+    for t in _MUSTACHE_RE.sub(" ", value).split():
+        if not _CLASS_TOKEN_RE.match(t):
+            continue
+        if t.endswith(("-", "_")):
+            if len(t.rstrip("-_")) >= _PREFIX_MIN_STEM:
+                out.append(t + PREFIX_MARK)
+            continue
+        out.append(t)
+    return out
 
 
 def _dynamic_class_tokens(expr: str) -> list[str]:
@@ -336,7 +376,13 @@ def class_references(path: str, text: str) -> dict[str, int]:
     files that carry no markup (by suffix). Reads the static `class=` /
     `className=` attributes, the Vue and React dynamic forms and Svelte's
     `class:x` directive; never a CSS selector (`.x {` is a definition, read
-    by extract_definitions) and never a script's `querySelector('.x')`."""
+    by extract_definitions) and never a script's `querySelector('.x')`.
+
+    Two forms name classes without spelling them out, and both are read
+    (#2970): a transition `name=` stands for every class the framework
+    generates from it, and a concatenated name contributes the prefix
+    reference `head-*` — which resolve_consumers matches against every row
+    whose symbol starts with `head-`."""
     if not (path or "").lower().endswith(_TEMPLATE_SUFFIXES):
         return {}
     counts: dict[str, int] = {}
@@ -351,6 +397,11 @@ def class_references(path: str, text: str) -> dict[str, int]:
         expr = next((g for g in m.groups() if g is not None), "")
         bump(_dynamic_class_tokens(expr))
     bump([m.group(1) for m in _SVELTE_CLASS_RE.finditer(text)])
+    for m in _TRANSITION_NAME_RE.finditer(text):
+        name = next((g for g in m.groups() if g is not None), "").strip()
+        if not _CLASS_TOKEN_RE.match(name):
+            continue
+        bump([name + suffix for suffix in _TRANSITION_SUFFIXES])
     return counts