Stage O-C: the event-driven DoE driver -- DOE returns to the prompt, EV-DONE chains the trials, MU-WAIT-ALL deleted (FABRIC-3.9.0 §3/§7.4)

- DOE sets up, JOINs EV-DONE and starts trial 1, then returns. Each trial
  births and sends WL-RUN only; completion arrives as the OS's EV-DONE.
- ON-DONE counts this campaign's own workers while active; the last one
  ends the trial (KILL all, marker, persist) and starts the next, or
  finishes (HB-OFF, UNJOIN, MU-CAMPAIGN: complete). MU-WAIT-ALL is gone;
  the start/end cycle goes through MU-END-XT.
- WL-DONE-ARGS removed from all ten workload capsules; lint passes.

Smoke campaign (amd64, 1 rep, rows off per Captain Bob): DOE returns, the
prompt answers mid-trial, all 6 trials chain on events, fail=0 each,
28/28 born/killed/departed, MU-CAMPAIGN: complete in ~61 min. Standard
sequence passes on all three ISAs (with the xHCI fix it exposed, df150e86).

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

capsules/per-isa-doe.4th

@@ -1,7 +1,7 @@
 Block 5117
 ( per-isa-doe.4th - per-ISA DoE driver. FABRIC-3 SXXXIV.4/     )
 ( SXXXV.5/.7: 6-cell factorial from multiuser-doe.4th's own    )
-( MU-EXEC-CAMPAIGN, unchanged. Seed/reps are VARIABLEs, not    )
+( MU-EXEC-CAMPAIGN. Seed/reps are VARIABLEs, not               )
 ( CONSTANTs -- settable before a run. Default N=3 reps/cell=   )
 ( 18 trials/ISA (ratified 2026-09-17). Load multiuser-doe.4th  )
 ( FIRST.                                                       )
@@ -15,7 +15,9 @@ Block 5119
 ( Tags, checks resume count, runs the campaign. Any experiment )
 ( goes through this one word -- run ONE per boot (one QEMU at  )
 ( a time). See FABRIC-3.md SXXXV.12 for why MU-EMIT-TRIAL-     )
-( MARKER can't just be redefined instead.                      )
+( MARKER can't just be redefined instead. FABRIC-3.9.8 O-C:    )
+( DOE starts trial 1 and RETURNS to the prompt; the campaign   )
+( runs on EV-DONE events and ends with MU-CAMPAIGN: complete.  )
 : DOE ( seed reps isa-addr isa-u -- )
   2DUP MU-ISA-TAG!
   DOE-RESUME-COUNT MU-EXEC-CAMPAIGN ;