feat(scanners): model/effort routing becomes a lever, not a 25th dimension (C4)

New GAP finding CA-GAP-028: authored subagents exist and not one of them names
`model:` or `effort:`, so every delegated task runs on the main conversation's
model (`model` defaults to `inherit`). Cites BP-MODEL-001/002, landed in C1.
`whats-active` and `manifest` now carry `model`/`effort` per agent.

Shipped as a conditional LEVER rather than a 25th dimension, and the choice was
made by measurement: as a t3 dimension the agent-less marketplace-medium fixture
would count it vacuously-present, moving the denominators 41->42 and utilization
44->45 — which flips `segment` "Developing"->"Competent" in the frozen v5.0.0
posture baseline, a field strip-retired-gap.mjs does not mask. A lever never
enters those denominators. The general rule is now an invariant in CLAUDE.md.

One check across both axes, not one per axis: it fires only when neither is used
anywhere, so a deliberate everything-on-one-model policy stays silent. Cost is
recall, chosen for precision.

Found by dogfooding, fixed red-first: `model: inherit` is the documented default
spelled out, so it must not count as routing — otherwise a config opts out of the
opportunity without changing anything real.

Two pre-existing defects surfaced and closed on the way:
- The humanizer guard asserted TRANSLATIONS.GAP.static EQUALS the dimension
  titles, which forbade humanizing any lever — all three existing levers fell
  through to the generic "feature opportunity" default, wrong for a budget lever.
  Guard now requires coverage of every emittable title, seen red against those
  three before the entries were written.
- Two hand-written copies of the lever list (finding-codes guard, humanizer
  guard) merged into one exported LEVERS registry carrying code AND title.
- suppression-validation pinned CA-GAP-028 as an unoccupied number; C4 claimed
  it. Fixed structurally with a derived first-free id, not by picking a new
  literal — same class as #60's "bump this again".

Suite 1596/0. Frozen v5.0.0 snapshots untouched.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pq3nye21RVYk4pZLeT8pGz

scanners/lib/active-config-reader.mjs

@@ -817,7 +817,7 @@ export async function enumerateRules(repoPath, pluginList = []) {
  *
  * @param {string} repoPath
  * @param {Array<{name:string, path:string}>} [pluginList]
- * @returns {Promise<Array<{name:string, source:string, pluginName:string|null, path:string, bytes:number, estimatedTokens:number, loadPattern:string, survivesCompaction:string, derivationConfidence:string}>>}
+ * @returns {Promise<Array<{name:string, source:string, pluginName:string|null, path:string, bytes:number, estimatedTokens:number, model:string|null, effort:string|null, loadPattern:string, survivesCompaction:string, derivationConfidence:string}>>}
  */
 export async function enumerateAgents(repoPath, pluginList = []) {
   const out = [];
@@ -842,6 +842,11 @@ export async function enumerateAgents(repoPath, pluginList = []) {
         path: f.path,
         bytes: f.size,
         estimatedTokens: estimateTokens(f.size, 'frontmatter'),
+        // Routing axes (C4). Explicit null rather than an absent key: `model`
+        // defaults to `inherit` and `effort` to the session level, so a consumer
+        // must be able to read "not pinned" without guessing (BP-MODEL-001/002).
+        model: hasText(frontmatter && frontmatter.model) ? frontmatter.model.trim() : null,
+        effort: hasText(frontmatter && frontmatter.effort) ? frontmatter.effort.trim() : null,
         ...lp,
       });
     }

scanners/lib/finding-codes.mjs

@@ -209,8 +209,11 @@ export const FINDING_CODES = {
   },
 
   // ── GAP: feature-gap-scanner ────────────────────────────────────────────
-  // Keys are GAP_CHECKS[].id (already stable). Dimensions 1–24 in table order,
-  // then the three conditional levers, which the scanner emits after the loop.
+  // Keys are GAP_CHECKS[].id for dimensions, and the lever code for the
+  // conditional levers the scanner emits after the loop. Numbers 1–24 happen to
+  // follow the current table order because that is how the dimensions were first
+  // published — NOT because position determines the number. A new check takes the
+  // next free number wherever it sits in the file (M-BUG-28).
   GAP: {
     t1_1: 1,
     t1_2: 2,
@@ -239,6 +242,7 @@ export const FINDING_CODES = {
     'bundled-skills-lever': 25,
     'cli-over-mcp-lever': 26,
     'filter-hook-output-lever': 27,
+    'agent-model-routing-lever': 28,
   },
 };
 

scanners/lib/humanizer-data.mjs

@@ -524,6 +524,30 @@ export const TRANSLATIONS = {
         description: 'Language-server connections let Claude see types, error messages, and definitions the same way your editor does.',
         recommendation: 'Set up LSP integration if you work in a typed language.',
       },
+      // Conditional levers. These are not "a feature you haven't set up" — they
+      // fire only under a measured condition, so the generic _default would
+      // misdescribe them. Every title the scanner can emit needs an entry here
+      // (guarded in tests/scanners/feature-gap-scanner.test.mjs).
+      'Bundled skills add to an over-budget skill listing': {
+        title: 'Built-in skills are crowding an already-full skill list',
+        description: 'Claude Code loads its own built-in skills into the same limited list as yours. Your list is already over budget, so entries risk being cut off and Claude may miss the right skill.',
+        recommendation: 'Turn off the built-in skills to free up room — unless you use them, in which case shorten your own skill descriptions instead.',
+      },
+      'Prefer CLI over MCP for common operations': {
+        title: 'Some connected services load their full tool list every turn',
+        description: 'Most connected services only cost tokens when used, but yours are set to load everything upfront. That weight is there whether you use them or not.',
+        recommendation: 'For services with a command-line equivalent (like `gh` or `aws`), the command line costs nothing until you run it.',
+      },
+      'Filter hook output before it enters context': {
+        title: 'An automation is pasting its full output into the conversation',
+        description: 'An automation that injects its output adds it to every turn that follows. Unfiltered command output can be much larger than the part that actually matters.',
+        recommendation: 'Trim the output inside the script itself, so only the useful lines reach the conversation.',
+      },
+      'Subagents pin neither model nor effort': {
+        title: 'Your helper agents all run at the same cost as your main session',
+        description: 'A subagent that names no model inherits the one you are using, so routine delegated work costs the same as your hardest work. Reasoning effort is a separate dial with the same default.',
+        recommendation: 'Give mechanical agents (search, extraction, summarizing) a smaller model or a lower effort level, and keep the strong settings for the work that needs judgement.',
+      },
     },
     patterns: [],
     _default: {