diff --git a/.claude/skills/local-dev/evals/evals.json b/.claude/skills/local-dev/evals/evals.json
index a95355ce..d07254b1 100644
--- a/.claude/skills/local-dev/evals/evals.json
+++ b/.claude/skills/local-dev/evals/evals.json
@@ -4,7 +4,7 @@
     "expect": "local-dev"
   },
   {
-    "prompt": "I added a dependency and the TUI bundle broke at import time. Where should it have gone?",
+    "prompt": "I added a package and now one of the client bundles fails at run time. What do I check?",
     "expect": "local-dev"
   },
   {
@@ -16,7 +16,7 @@
     "expect": "local-dev"
   },
   {
-    "prompt": "I just pulled and a client's dependencies look out of sync. What do I need to run?",
+    "prompt": "Do I need to do anything special to set this repo up inside a git worktree?",
     "expect": "local-dev"
   },
   {
diff --git a/.claude/skills/test-servers/SKILL.md b/.claude/skills/test-servers/SKILL.md
index 2e8b91b6..16556b18 100644
--- a/.claude/skills/test-servers/SKILL.md
+++ b/.claude/skills/test-servers/SKILL.md
@@ -1,6 +1,6 @@
 ---
 name: test-servers
-description: Run a composable MCP test server by hand — pick the showcase config that reproduces a given feature or bug, build test-servers, and connect with the right protocol era. Covers the stale-build hazard.
+description: Run a composable MCP test server by hand — pick the showcase config for a feature or bug, build it, and connect with the right protocol era. Use when a change, a PR or a smoke test needs a real server to exercise it; when reproducing a reported bug by hand; when choosing which fixture or protocol era to run; when a fixture keeps serving stale code after an edit; or when the config or preset you need does not exist yet.
 disable-model-invocation: false
 ---
 
diff --git a/.claude/skills/test-servers/evals/evals.json b/.claude/skills/test-servers/evals/evals.json
index ba117347..237fece3 100644
--- a/.claude/skills/test-servers/evals/evals.json
+++ b/.claude/skills/test-servers/evals/evals.json
@@ -8,7 +8,7 @@
     "expect": "test-servers"
   },
   {
-    "prompt": "I renamed a file under test-servers/src and the fixture is still running the old code. Why?",
+    "prompt": "I need a real server to exercise this change against by hand. What do I run?",
     "expect": "test-servers"
   },
   {
diff --git a/.claude/skills/testing/SKILL.md b/.claude/skills/testing/SKILL.md
index dbbb4438..7a597e4c 100644
--- a/.claude/skills/testing/SKILL.md
+++ b/.claude/skills/testing/SKILL.md
@@ -11,6 +11,12 @@ statements, functions, and branches.** That rule and the React/Mantine
 conventions live in [`AGENTS.md`](../../../AGENTS.md); this skill is where a
 test goes, how to run it, and how to clear the gate.
 
+⚠️ **Anything that needs a real server to run against — an integration test, a
+smoke, reproducing a bug by hand — is `/test-servers`, and you have to load it.**
+Integration and smoke tests here drive a real server over a real transport
+rather than a mock, so picking, building and connecting to a fixture is a
+procedure of its own that this skill does not carry.
+
 ## Where the test file goes
 
 **Side-by-side by default; `src/test/` only for what can't be co-located; and
diff --git a/AGENTS.md b/AGENTS.md
index 252c1e39..3455f38e 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -233,7 +233,7 @@ that from happening:
    overflows, and drops the least-invoked entries **first** — which are exactly the
    model-invoked skills that must fire on their own. `verify:skills` prints the
    current cost against the budget recorded in `scripts/lib/skill-manifest.mjs`
-   (2,921/4,000 characters as of this writing) and fails when it is exceeded. Raise
+   (3,144/4,000 characters as of this writing) and fails when it is exceeded. Raise
    the budget deliberately, or tighten a description; each entry is capped at 1,536
    characters regardless, so **put the key use case first**.
 
diff --git a/docs/skill-authoring.md b/docs/skill-authoring.md
index 113ebdc0..34947428 100644
--- a/docs/skill-authoring.md
+++ b/docs/skill-authoring.md
@@ -104,6 +104,21 @@ retired here:
 | "In `…/Foo.test.tsx` I need to assert on a Mantine transition mid-flight. How?" | `AGENTS.md` names `renderWithMantineTransitions` and states the rule outright. Also named a concrete file — two faults at once.          |
 | "What should I run before I push?"                                              | `AGENTS.md` states `npm run local:gate` is the mandatory pre-push command. Scored 40%.                                                   |
 
+**Partial overlap reads as flakiness, not as a miss.** A case the rules file
+answers _outright_ sits at 0% and is easy to spot. A case it answers _half_ of
+oscillates — and looks like eval noise rather than a defect in the case. Two of
+`local-dev`'s cases behaved exactly this way before being retired:
+
+| Case                                                                                           | Scores across runs        | The overlap                                                                              |
+| ---------------------------------------------------------------------------------------------- | ------------------------- | ---------------------------------------------------------------------------------------- |
+| "I added a dependency and the TUI bundle broke at import time. **Where should it have gone?**" | 33 / 67 / 100 / 100 / 60% | Dependency placement is stated in full in `AGENTS.md`; only the diagnosis is the skill's |
+| "I just pulled and a client's dependencies look out of sync. **What do I need to run?**"       | 80 / 80 / 60%             | `AGENTS.md` says a single root `npm install` is all you need                             |
+
+Both stabilised at 100% once re-aimed at what only the skill holds — "what do I
+**check**" instead of "where should it have **gone**", and the worktree install
+trap instead of the install command. If a case keeps moving between runs while
+its neighbours hold steady, suspect the case before you suspect the noise.
+
 The test to apply before committing a case: **could a reader answer this from
 the rules file alone?** If yes, it measures `AGENTS.md`, not the skill. Aim the
 case at what only the skill body holds — a live ID, a command sequence, a
@@ -151,11 +166,22 @@ lucky one, and it is still far cheaper than a full suite run.
 Then the suite:
 
 ```sh
-npm run skills:eval                    # every model-invoked skill, RUNS=3
+npm run skills:eval                              # every model-invoked skill, RUNS=3
 RUNS=5 CONCURRENCY=6 npm run skills:eval
-npm run skills:eval -- testing         # one skill's cases (still scores negatives against all)
+npm run skills:eval -- testing                   # one skill's cases
+npm run skills:eval -- testing test-servers      # a set of skills
 ```
 
+Narrowing the run never narrows what a **negative** case is scored against — a
+focused run still fails a negative that fires any model-invoked skill in the
+repo, because "no skill of ours fired" is the property being asserted. An
+unknown name is a hard error rather than an empty run, since a typo would
+otherwise report a green 0/0 that reads exactly like a clean pass.
+
+⚠️ **A focused run cannot see displacement.** Adding or reshaping a description
+changes the trigger rate of skills you did not touch, and only the full suite
+observes that. Use the filter to iterate; take the full suite before you push.
+
 **Read the noise before reading the result.** At `RUNS=3` one sample is worth 33
 points, and an untouched skill was observed swinging 100 points across two runs
 of the same suite. `RUNS=5` is the smallest setting where a single flake does
diff --git a/scripts/skill-eval.mjs b/scripts/skill-eval.mjs
index 2c8689a9..5325c1b3 100755
--- a/scripts/skill-eval.mjs
+++ b/scripts/skill-eval.mjs
@@ -25,8 +25,9 @@
 // Closing that would need a deterministic trigger oracle, which does not exist.
 //
 // Usage:
-//   npm run skills:eval                  # every model-invoked skill's cases
-//   npm run skills:eval -- testing       # one skill's cases
+//   npm run skills:eval                        # every model-invoked skill's cases
+//   npm run skills:eval -- testing             # one skill's cases
+//   npm run skills:eval -- testing test-servers  # several skills' cases
 //   RUNS=5 THRESHOLD=0.8 npm run skills:eval
 
 import { spawn } from "node:child_process";
@@ -58,11 +59,19 @@ const CONCURRENCY = Number(process.env.CONCURRENCY ?? 4);
  * (Copilot). Every model-invoked skill is inspected; `only` is applied when
  * enqueueing.
  *
- * @param {string | undefined} only
+ * A name that matches no model-invoked skill is a hard error rather than an
+ * empty run: a typo would otherwise enqueue nothing and the eval would report a
+ * green 0/0, which reads exactly like a clean pass of the skill you meant.
+ *
+ * @param {string | string[] | undefined} only One or more skill names.
  * @param {string} [skillsDir]
  * @returns {{ cases: object[], ours: Set<string> }}
  */
 export function collectCases(only, skillsDir = SKILLS_DIR) {
+  const wanted =
+    only === undefined || only === null
+      ? null
+      : new Set(Array.isArray(only) ? only : [only]);
   const cases = [];
   const ours = new Set();
   for (const dir of readdirSync(skillsDir).sort()) {
@@ -103,9 +112,18 @@ export function collectCases(only, skillsDir = SKILLS_DIR) {
     if (invalid.length > 0) {
       throw new Error(`${dir}/evals/evals.json: ${invalid.join("; ")}`);
     }
-    if (only && dir !== only) continue;
+    if (wanted && !wanted.has(dir)) continue;
     for (const c of parsed) cases.push({ ...c, from: dir });
   }
+  if (wanted) {
+    const unknown = [...wanted].filter((n) => !ours.has(n));
+    if (unknown.length > 0) {
+      throw new Error(
+        `no model-invoked skill named ${unknown.map((n) => `\`${n}\``).join(", ")} — ` +
+          `known: ${[...ours].sort().join(", ")}`,
+      );
+    }
+  }
   return { cases, ours };
 }
 
@@ -310,7 +328,9 @@ async function main() {
     process.exit(1);
   }
 
-  const { cases, ours } = collectCases(process.argv[2]);
+  const { cases, ours } = collectCases(
+    process.argv.length > 2 ? process.argv.slice(2) : undefined,
+  );
   if (cases.length === 0) {
     console.error("skills:eval — no cases found.");
     process.exit(1);
diff --git a/scripts/skill-eval.test.mjs b/scripts/skill-eval.test.mjs
index 7c8536f8..a6b3ae99 100644
--- a/scripts/skill-eval.test.mjs
+++ b/scripts/skill-eval.test.mjs
@@ -322,6 +322,42 @@ test("focused mode narrows the cases but not the repo's own skill set", () => {
   rmSync(root, { recursive: true, force: true });
 });
 
+test("focused mode accepts several skill names", () => {
+  const root = skillsFixture();
+
+  const focused = collectCases(["alpha", "beta"], root);
+  assert.deepEqual(focused.cases.map((c) => c.prompt).sort(), [
+    "a+",
+    "a-",
+    "b+",
+    "b-",
+  ]);
+  // Narrowing to every skill is still not the same as no filter — `ours` is
+  // unchanged either way, which is what keeps negative scoring honest.
+  assert.deepEqual([...focused.ours].sort(), ["alpha", "beta"]);
+
+  // A single name keeps working, so the one-argument form is unaffected.
+  assert.deepEqual(
+    collectCases("beta", root).cases.map((c) => c.prompt),
+    ["b+", "b-"],
+  );
+
+  rmSync(root, { recursive: true, force: true });
+});
+
+test("an unknown skill name is an error, not an empty run", () => {
+  // A typo would otherwise enqueue zero cases and report a green 0/0, which
+  // reads exactly like a clean pass of the skill that was meant.
+  const root = skillsFixture();
+  assert.throws(
+    () => collectCases(["alpha", "aplha"], root),
+    /no model-invoked skill named `aplha`/,
+  );
+  // A name-only skill is not model-invoked, so asking for it is the same error.
+  assert.throws(() => collectCases(["gamma"], root), /no model-invoked skill/);
+  rmSync(root, { recursive: true, force: true });
+});
+
 test("a name-only skill is not part of the repo's model-invoked set", () => {
   const root = skillsFixture();
   const { ours } = collectCases(undefined, root);