Bracket std79 DoE trial loop with HB-ON/HB-OFF, capture real heartbeat CSVs

Every prior std79-doe.fth run's automatically-extracted CSV
(scripts/extract_doe.sh) was silently empty -- g_doe_log_enabled
(doe_log.c) defaults off, and nothing in the campaign ever called HB-ON.
EXEC-STD79-DOE now calls HB-ON right before its trial loop and HB-OFF
right after, so the per-heartbeat-tick physics/timing CSV (18 columns:
tick_number, hot_word_count, avg_word_heat_q48, apic_ticks, per-VM
heat_q48, etc.) finally covers the run's own window on all three
architectures.

Found and fixed two bugs along the way, one in a comment and one in the
ad hoc QEMU orchestration script used to drive these runs (not part of
this repo):

- std79-doe.fth's own explanatory comment accidentally spelled out the
  literal "[HADES][DOE ]" tag string doe_log.c prefixes each row with --
  the FORTH REPL's compile-time echo of that comment then matched
  scripts/extract_doe.sh's own extraction grep, corrupting the first
  extracted CSV row with comment text instead of real telemetry. Fixed by
  never spelling out the literal substring.

- The harness script's completion-detection watched for "STD79-DOE:
  complete" anywhere in the log since before the whole capsule was fed,
  which matches the colon definition's own compile-time echo of that same
  string literal, not just the real end-of-run print. Without HB-ON the
  entire 27-trial run finished in a few seconds -- faster than one poll
  interval -- so the false match and the real one always landed in the
  same window and this never surfaced. HB-ON's added per-tick console I/O
  slowed real execution enough to expose it: the script sent BYE the
  moment compilation finished, truncating every trial after whatever
  point compilation had reached (aarch64 lost 9 of 27 trials this way on
  the first attempt). Fixed by feeding definitions and invocation as two
  genuinely separate connections, with the completion-watch window opened
  only after compilation is confirmed landed.

Verified 27/27 trials correct on every architecture via the campcampaign's
most distinctive result markers (both M*/M/MOD 18-19 digit values and the
2147483648 2/ result, all exactly 27 occurrences, zero faults) rather than
exact substring reconstruction: HB-ON's async per-tick CSV printer and the
trial loop's own console output share the same serial line with no
locking, so CSV rows can splice mid-token into trial output on the wire
(confirmed live -- cosmetic only, the underlying FORTH execution and
values are unaffected). results-20260912-with-heartbeat-csv/ holds both
the raw logs and their paired heartbeat CSVs; the earlier truncated runs'
logs are kept too (never delete logs) as the record of how this was found.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EXieurDfDSsDFdnSyusuWo

experiments/std79-doe/std79-doe.fth

@@ -163,11 +163,27 @@ VARIABLE CURR-RUN-ID
   CURR-ID @ ID-LABEL TYPE ." ," CURR-REP @ . CR
   N-TESTS 0 DO I RUN-TEST LOOP ;
 
+( HB-ON/HB-OFF (doe_log.c) bracket the trial loop below so the per-tick )
+( DoE-tagged physics/heartbeat CSV -- 18 columns: tick_number, elapsed_ns, )
+( hot_word_count, avg_word_heat_q48, window_width, apic_ticks, )
+( hera/hermes/artemis heat_q48, etc. -- covers exactly this run's window, )
+( not the whole boot. g_doe_log_enabled defaults OFF (doe_log.c), so )
+( every prior campaign run's extracted CSV (scripts/extract_doe.sh, run )
+( automatically at the end of every `make qemu`) was silently empty; )
+( without this bracket there is no per-tick data to analyze the 3x9x3 )
+( factorial's physics behavior by, only the DOE-RUN/DOE-HEADER correctness )
+( lines already printed below. NOTE: this comment deliberately never )
+( spells out the literal tag string doe_log.c prefixes each row with -- )
+( writing it here once already corrupted a real extracted CSV live )
+( 2026-09-12, since scripts/extract_doe.sh greps the log for exactly that )
+( substring and can't tell a real telemetry row from this comment's own )
+( compile-time echo saying the same characters. )
 : EXEC-STD79-DOE ( seed lo hi -- )
   ACTIVE-HI !  ACTIVE-LO !
   SEED
   INIT-MATRIX SHUFFLE-MATRIX
   ." DOE-HEADER,run_id,id_idx,id_label,rep" CR
+  HB-ON
   N-RUNS 0 DO
     I MATRIX@
     DUP N-REPS /
@@ -177,4 +193,5 @@ VARIABLE CURR-RUN-ID
       DROP DROP
     THEN
   LOOP
+  HB-OFF
   ." STD79-DOE: complete" CR ;