test(memory): bound what P1's green does and does not establish (P1 follow-up)

Two discipline holes left after 1309afe / 09be4de, both closed here.

1. The boundary was unstated. A one-hot keyword-family fixture proves the
   PLUMBING — that the computed query vector reaches scoring — and says nothing
   about retrieval quality. Left implicit, a green P1 invites the reading
   "semantic recall works". The measured counter-evidence is now in the file:
   on the real chinese-clip space a true hit scored 0.8345 while an unrelated
   block scored 0.8598, so absolute scores are not calibrated and no threshold
   may be read off them. That is a known unresolved problem outside P1's scope.

2. `dsh` missing used to `t.skip`. A skip keeps `npm test` green while the only
   end-to-end evidence for P1 never runs — the same shape as a criterion that is
   committed but never speaks. It now fails, and says why.

No behavioural change: 272/272 tests, 12/12 checkpoints, 0 skipped on a box
where `dsh` is present. Verified the mutation discipline still bites — deleting
`'hybrid'` from ORDINARY_DEGRADATIONS turns L10, L11, L10† and L11† red.

test/phase-b-p1-vector-wiring.test.js

@@ -47,6 +47,15 @@
  *
  * Without P1a/P1b a passing test would only show that *something* answered.
  *
+ * ★ What this does NOT establish.
+ * A one-hot keyword-family fixture proves PLUMBING, not retrieval quality.
+ * It cannot speak to how a real embedder ranks real Chinese sentences — that
+ * boundary was measured separately and is a KNOWN UNRESOLVED problem outside
+ * P1's scope: on the real chinese-clip space a true hit scored 0.8345 while an
+ * unrelated block scored 0.8598, so absolute scores are not calibrated and no
+ * threshold may be read off them. A green P1 means "the wiring carries the
+ * vector", never "semantic recall works".
+ *
  * ## The corpus, and why these exact strings
  *
  * The fake embedder is a deterministic keyword-family projection into 8 unit
@@ -62,21 +71,25 @@
  * extractor (`[A-Z]{2}[0-9]{2}-[0-9]{3}`) can find it and nothing else in the
  * prompt can collide with it.
  *
- * ## Skip conditions
+ * ## Missing-harness conditions
  *
- * The harness needs `dsh` and the two `dsh-base` peers resolvable from this
- * package. When they are not installed there is no headless process to drive, and
- * the test skips LOUDLY rather than asserting against a half-mounted app — the
- * same rule `loop-system-e2e.test.js` follows.
+ * The harness needs `dsh` resolvable from PATH. When it is not, there is no
+ * headless process to drive, and the criterion FAILS rather than skipping.
+ *
+ * ★ Why `assert.fail` and not `t.skip`: a skip is green. `npm test` would report
+ * "1 skipped, N passed" and the only end-to-end evidence for P1 would never run —
+ * exactly the "criterion is in the repo but never speaks" shape this whole slice
+ * exists to close. It is also worse than a plain hole, because a green suite reads
+ * as proof. `loop-system-e2e.test.js` still skips in the same situation; that file
+ * was not the subject of P1 and is not changed here.
  *
  * @module dsh-memory/test/phase-b-p1-vector-wiring
  */
 
 import assert from 'node:assert/strict'
 import { execFileSync, spawn } from 'node:child_process'
-import { createReadStream, existsSync, mkdtempSync, rmSync } from 'node:fs'
+import { existsSync, mkdtempSync, rmSync } from 'node:fs'
 import { createServer } from 'node:http'
-import { createServer as createNetServer } from 'node:net'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { fileURLToPath } from 'node:url'
@@ -573,8 +586,11 @@ test('P1-0: the corpus is admissible — symbol path blind, vector path reaches
 
 test('P1: a semantic-only question is answered from block memory via the vector route', async (t) => {
   if (!dshAvailable()) {
-    t.skip('no `dsh` binary on PATH — the headless harness cannot be driven here')
-    return
+    assert.fail(
+      'the P1 end-to-end criterion cannot be established: no `dsh` binary on PATH. ' +
+      'This is a SKIP-shaped hole, not a pass — a silent skip would keep npm test green ' +
+      'while the only end-to-end evidence for P1 never runs.',
+    )
   }
 
   const workspace = mkdtempSync(join(tmpdir(), 'p1-e2e-'))