cvf86 controller_branch diag (commit 708c121f2) revealed:
rollout_steps: 99.99% WIDEN, 0% HOLD, 0% SHRINK
The bounded-step + noise-floor fix was correctly applied, but the
controller WIDENED 99.99% of steps because the hardcoded
ADV_VAR_RATIO_TARGET = 0.1 (`#define` in the kernel) was a b_size>1
design choice. The streaming-EMA regime at b_size=1 has var/|mean|
naturally living in [1, 10] (median 3.9), so input is ALWAYS >> 0.1
and the controller correctly says "noisy advantages → widen". Result:
n_rollout pegs at MAX=8192 within ~5 steps and stays for 50k steps,
PPO update frequency drops 4×, KL stays in numerical noise (median
1.7e-8), Q can't learn (l_q stuck at ~2.7 vs uniform 3.04).
## Fix: ISV-driven target
Per `feedback_isv_for_adaptive_bounds`: ADV_VAR_RATIO_TARGET now
lives in ISV slot 449 (`RL_ADV_VAR_RATIO_TARGET_INDEX`), seeded at
trainer init to 5.0 (matches streaming-regime median 3.9). The
controller reads `isv[RL_ADV_VAR_RATIO_TARGET_INDEX]` each step
instead of a `#define`.
Expected behavior at TARGET=5.0:
* Median input 3.9 lands in-band [3.33, 7.5] → HOLD
* n_rollout stays near BOOTSTRAP=2048 instead of MAX
* 4× more PPO updates per step → policy actually moves
* KL leaves noise floor → ε controller activates
* Q has gradient signal → can learn
Noise floor is now derived multiplicatively from the ISV target
(`target × ADV_VAR_RATIO_NOISE_FLOOR_FRAC = 0.01`) so adjusting
the target proportionally adjusts the floor — no separate slot
needed.
## Wiring
`rl_streaming_clamp_init.cu` extended to seed all three ISV-resident
design constants (adv_var clamp ceiling, td_kurt clamp ceiling, AND
adv_var regression target). Single kernel call at trainer init —
still no HtoD per `feedback_no_htod_htoh_only_mapped_pinned`.
## Diag bake-in
`controller_branch.rollout_steps_target` now reads from
`isv[RL_ADV_VAR_RATIO_TARGET_INDEX]` instead of the prior hardcoded
`0.1f32` literal. The diag shows the current ISV-resident target
so post-hoc branch analysis uses the actual value the controller
saw, and lets us track whether a future adaptive controller (one
that maintains target from observed-input percentile EMA) is
moving the target correctly.
## Slot allocation
RL_SLOTS_END: 449 → 450 (one new design-constant slot).
## Test updates
G1 (isv_bootstrap) + G3 (r5_controllers) skip slot 449 in the
sentinel-zero loop and assert the seeded value (5.0) separately.
G3's `advantage_var_ratio` input bumped from 5.0 → 20.0 so the
WIDEN branch still fires (input > new target × 1.5 = 7.5) and the
test still validates that the controller moves off bootstrap.
## Verified gates (local sm_86)
G1 isv_bootstrap ✅
G3 controllers ✅ (with updated input)
G4 target_update ✅
integrated_smoke ✅
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
95dcc4e312