docs(v4.0.0): step 6b -- POST is the kernel's: design, acceptance and plan

NUCLEUS.md 6.3 and section 7 as approved 2026-10-07: the kernel holds the
cases as a table and feeds them to the node; a runner judges from outside;
what the cases define stays, as in v3; a PARITY:V4_SYSTEM line after POST.
The capsule harness and its two nucleus variables are withdrawn (6.3a
keeps what they were).  MESH.md step 6b has the acceptance.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/v4.0.0/MESH.md

@@ -704,11 +704,28 @@ Each is tested, committed and pushed before the next.
    identities, a device joining at the end and known when it returns,
    release by asking, holes. Its acceptance is to be approved before it is
    built.
-   **6b. POST is the kernel's.** Ruled 2026-10-07 (section 9): the kernel
-   holds POST's cases and feeds them to Hera itself, with no POST words
-   loaded into her dictionary. Today they are a capsule she loads
-   (`NUCLEUS.md` section 6). Its design and acceptance are to be approved
-   before it is built.
+   **6b. POST is the kernel's.** Ruled 2026-10-07 (section 9); design
+   approved 2026-10-07, `NUCLEUS.md` 6.3 and section 7. Acceptance, as
+   approved:
+   1. *Same verdict.* The three hosted programs and the three bare-metal
+      boots print `PARITY:V4_POST tests=538 pass=538 fail=0`,
+      `PARITY:V4_SYSTEM word_count=N dict_hash=0x...`, `PARITY:OK` and
+      `POST: PASSED`, with the same hashes on all six.
+   2. *Nothing of the harness is on the node.* At the prompt `T{` is an
+      unknown word, and `(CATCH)` and `(EMIT-HOOK)` are gone from the
+      nucleus.
+   3. *What the cases define is there.* A word a case defines can be used
+      at the prompt after boot, and survives `COLD`.
+   4. *The judge can fail.* Given a case with a wrong expected stack, one
+      with wrong expected output, one that must end in an error and does
+      not, and one that ends in an error and must not, the runner reports
+      each as a failure by name, and a boot with a failing case ends
+      `PARITY:FAIL`, `POST: FAILED`.
+   5. *A case's printing does not reach the console.* The boot log shows
+      nothing that a passing case printed.
+   6. *The suite.* `make -C v4 test` and `sanitize` pass at both widths;
+      `mkcapsule --lint capsules/` is clean.
+
 7. **A second unit; scaling while running; sleep, wake and kill by
    command.**
 8. **The hosted product is the five nodes**, on three ISAs: acceptance 1