Stage O-A: the Tripod is an observer -- outside the compudynamic comparison, acting on events (FABRIC-3.9.0 §2, 3.9.8)

Observer flag on switch-signal slots, set by the kernel for the Tripod
(is_fleet_foundation, hoisted; Hera in kernel_main). The decision: an
observer in progress or holding an event keeps the CPU; observers with
events (mail, Hera's console input) go ahead of participants, oldest wait
stamp first; participants compared by work heat as before. Observers are
never charged (O-2) nor floored. Uncommitted heat-share charge discarded.

Evidence, byte-identical amd64/aarch64/riscv64: G interleave unchanged;
Hestia's mail runs before any worker output (HHHABB...); a line typed
while two workers run is read and executed mid-stream (...ABAB1 2 + . /
3 ok / ABAB...) -- console responsive under load. Relay 3, dict_hash
unchanged. Busy-wait DOE deliberately not run (deadlocks by design until
O-C). FABRIC-3.9.0 records rulings and Captain Bob's messaging note (§7).

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

FABRIC-3.9.8.md

@@ -22,7 +22,7 @@ Evidence is named **before** each stage runs.
 
 | Stage | Change | Evidence (named in advance) |
 |---|---|---|
-| **O-A** | Observer role (`FABRIC-3.9.0.md` §2.1). The absolute-heat-share charge is discarded (ruling 5). Observers are left out of the decision's candidates, the work-heat charge and the floor. (Also the absolute charge, if O-2 is ruled so.) Observers with events go ahead at clean boundaries, among themselves by wait stamp (§2.4, per O-1). | The standard sequence. A probe (reverted after capture) shows the decision never returning an observer as a heat candidate, and an observer with mail switched to at the next participant checkpoint. **The busy-wait DoE driver, unchanged, run as a cfg-0 trial with rows on for a fixed window:** Hera's share of rows falls from about ½ (the stopped relaunch's tail) to near 0 while both workers have work. That is the measured symptom this design exists to fix. |
+| **O-A** | Observer role (`FABRIC-3.9.0.md` §2.1). The absolute-heat-share charge is discarded (ruling 5). Observers are left out of the decision's candidates, the work-heat charge and the floor, and (O-2) the absolute charge. Observers with events go ahead at clean boundaries, among themselves by wait stamp (§2.4, per O-1). | *(Corrected before starting.)* The standard sequence, with the G interleave unchanged. **Console responsive under load:** `1 2 + .` typed while `wa`/`wb` run prints `3` in the middle of the A/B stream. **Observer precedence:** a message to Hestia sent in the same line as the two worker jobs runs before any `A`/`B`. **Not run: the busy-wait DoE driver.** Under O-1, Hera running `DOE` is an observer acting on an event, and nothing displaces her, so `MU-WAIT-ALL` would wait forever. The originally named evidence ("Hera's share falls on the unchanged busy-wait driver") contradicts the design. `DOE` stays unrun until O-C replaces the driver. |
 | **O-B** | Hera's own mail drained at `sk_vm_idle_point()`, with the readline `n > 0` gate; the timer-paced pump drain removed (§2.5). | The standard sequence, plus: a message sent to Hera while she sits idle at the prompt is acted on **without waiting for the idle beat**. A probe records the delay in beats from admission to drain; it must be well under `SK_IDLE_BEAT_INTERVAL`. The relay and BLK-ATTACH flows are unchanged. |
 | **O-C** | An event-driven DoE driver (§3): `DOE` starts trial 1 and returns to the prompt; `MU-DONE` counts, ends trials and starts the next; `MU-WAIT-ALL` is deleted. Capsule only. | A 1-rep smoke campaign on amd64 runs all 6 cells to `MU-CAMPAIGN: complete`, with every trial `fail=0` and N/N `KILL … dead`. Hera's rows during trials are only event handling. The prompt answers typed input while trials run. Then the standard sequence on all three ISAs. |
 | **O-D** | The DoE relaunch: `12345 3 S" <isa>" DOE`, amd64, then aarch64, then riscv64, with the ring extracted between ISAs and `artemis.img` **not** reset in between. | A fresh time estimate from O-C's measured row rate, **before** launch. Then per ISA: 18 `MU-TRIAL` markers, `fail=0`, `MU-CAMPAIGN: complete`. |
@@ -37,4 +37,50 @@ Evidence is named **before** each stage runs.
 
 ## 2. Execution log
 
-*(empty: no stage started)*
+- [x] **Stage O-A — the observer role (`FABRIC-3.9.0.md` §2).** 2026-09-24. Captain Bob: *"all as
+      proposed, go ahead with O-A"* (O-1 to O-4 and the discard, all as proposed).
+      - **Discarded:** the uncommitted absolute-heat-share charge (`git checkout` of
+        `capsule_vm_physics.c/.h`), per ruling 5.
+      - **`capsule_vm_switch_signal.c/.h`:**
+        - Each slot carries an `observer` flag, with `sk_vm_switch_signal_set_observer()` and
+          `is_observer()`.
+        - `sk_vm_switch_decide()` now works in tiers:
+          1. An observer that is itself in progress (a live non-IDLE frame) or holding an event
+             keeps the CPU.
+          2. Otherwise, an observer with an event, meaning mail (or console input, for Hera),
+             goes ahead of every participant. Among observers, the oldest wait stamp wins.
+          3. Otherwise, participants are compared by work heat exactly as in FABRIC-3.8.
+             Observers are never heat candidates.
+        - `note_work_gained()` never floors an observer and leaves observers out of the floor
+          set. The running VM counts only if it is a participant.
+      - **`capsule_birth.c`:** `is_fleet_foundation` is hoisted to function scope. Registration
+        marks the Tripod as observers from that same birth-time fact.
+      - **`kernel_main.c`:** Hera is marked an observer where she registers.
+      - **`vm_runtime.c`:** observers are not charged at all (O-2).
+      - Nothing a VM executes can set or clear the role.
+
+      **Evidence, as corrected before starting (§1).** Ordinary words only, typed at
+      `[zuse@Hera] ok>`, byte-identical on all three ISAs (`logs/20260924-084904/amd64/`,
+      `-090107/aarch64/`, `-091424/riscv64/`):
+      - **G interleave unchanged:** A = 40, B = 40, 48 runs.
+      - **Observer precedence:** `S" LA" S" wa" SEND . S" LB" S" wb" SEND . S" 72 EMIT 72 EMIT
+        72 EMIT" S" Hestia" SEND .` gives `HHHABBAABBAA…`. Hestia's mail ran before any
+        participant output once Hera went idle.
+      - **Console responsive under load:** with `wa`/`wb` on 200 markers × 20,000-iteration
+        loops, `1 2 + .` typed mid-run appears as `…ABABAB1 2 + .` / `3  ok` / `ok> ABABBA…`.
+        Hera, an observer with console input, got the CPU at the next worker boundary, ran the
+        line, and the workers resumed. This is the C-4 (α) starvation recorded at C-b, fixed.
+        *(The first amd64 attempt at this check used loops that finished before the line was
+        typed, so it proved nothing. It was re-run with the heavy loops, and the script was fixed
+        for the other two ISAs.)*
+
+      **Acceptance** (same boots):
+      - All reach `[zuse@Hera] ok>` with zero `UNKNOWN WORD`, faults and frame corruption.
+      - The `dict_hash` set is unchanged from Stage I (word_count 531, M7.1a
+        `0x572daac83b797332`), since no words were added or removed.
+      - Mint → WIREBIND → `USE` → `1 2 + .` → `3`.
+      - Idle log growth: 0 bytes.
+      - Clean build on all three plus hosted, no new warnings.
+
+      **Not run, by design:** the busy-wait DoE driver, which would deadlock under O-1 (§1).
+      Don't run `DOE` until O-C.