diff --git a/commit0/SAMPLING_RESULTS.md b/commit0/SAMPLING_RESULTS.md
new file mode 100644
index 0000000..0e6f1cb
--- /dev/null
+++ b/commit0/SAMPLING_RESULTS.md
@@ -0,0 +1,62 @@
+# Sampling results — agent value-add significance (Tier-1, 2026-06)
+
+Step 4 of the validation plan: *characterize agent value-add variance and test significance,
+so "value-add" claims are distinguishable from LLM run-to-run noise.* Method: K=5 reps/cell
+via `repeat_runner` (valid-rep gating), each rep scored canonically by `score_branch`
+(commit0 full-suite), analyzed by `stats_analyze` (bootstrap 95% CIs, paired value-add Δ vs
+the single-shot baseline, BH-FDR q=0.05, sign-stability). **OpenAI (gpt-5.4), default
+temperature** (so variance matches the published numbers). Cost: **~$17.5**.
+
+## cachetools (near-saturated lib)
+| arch | pass% [95% CI] | Δ vs single_shot [CI] | sig |
+|---|---|---|---|
+| aider | 100.0 [100,100] | +13.0 [+2,+25] | |
+| smolagents | 99.7 [99,100] | +12.7 [+1,+24] | |
+| kaizen_delta | 95.5 [93,97] | +8.6 [−3,+21] | |
+| reflexion | 82.9 [81,85] | −4.1 [−16,+8] | |
+| single_shot (baseline) | 87.0 [75,98] | — | |
+
+**0/4 significant after BH-FDR.** Complementary pattern is visible (aider/smolagents win,
+reflexion regresses), but effects are small and the **baseline is noisy (87% ±12pp)**, so
+nothing survives multiple-comparison correction at K=5. Agentic archs are far more
+*reproducible* than single-shot (σ≈0 vs ≈12pp) — a finding in itself.
+
+## voluptuous (floor lib — architectural unlock)
+| arch | pass% [95% CI] | Δ vs single_shot [CI] | sig |
+|---|---|---|---|
+| **aider** | **88.7 [87,91]** | **+82.6 [+70,+90]** | **\*** |
+| smolagents | 40.0 [0,80] | +33.8 [−6,+80] | bimodal, n.s. |
+| reflexion | 24.7 [0,59] | +18.5 [−11,+51] | bimodal, n.s. |
+| kaizen_delta | 0.0 [0,0] | −6.2 [−19,+0] | no unlock |
+| single_shot (baseline) | 6.2 [0,19] | — | |
+
+**1/4 significant after BH-FDR (aider).**
+
+## What the sampling establishes (and corrects)
+1. **A real, large, reliable value-add:** aider unlocks voluptuous at **+82.6pp, significant
+   even at K=5** — the headline "agent value-add" claim, now with a CI.
+2. **Bimodal pseudo-unlocks exposed:** smolagents/reflexion *sometimes* crack voluptuous and
+   *sometimes* crash (149/149 vs 0/2 across reps) → wide CIs → **not significant**. A single
+   run would have over-claimed these as reliable unlocks; sampling shows they aren't.
+3. **A provider-specific over-generalization caught:** KD does **not** unlock voluptuous on
+   OpenAI (0/0/0, all 5 reps). The published "KD cracked voluptuous 0→39%" was **Sonnet-only**
+   and must be qualified to the provider.
+4. **Calibration:** significance tracks effect size vs noise — large unlocks clear K=5, small
+   near-saturated effects (cachetools) correctly do not. This is the cost-effective design:
+   sample the large-effect claim-bearing cells; near-saturated cells need much larger K.
+
+## Caveats / scope
+- **OpenAI only** (reliable on the run host); Anthropic-provider claims (incl. the Sonnet KD
+  voluptuous result) need a separate run when the provider is stable / off-peak.
+- **K=5** — bootstrap CIs are wide on bimodal cells; raising K tightens them where needed.
+- **reflexion** is scored at its *last* iteration (`score_branch`), vs the published *best*
+  iteration — may understate reflexion; refine if a reflexion claim is load-bearing.
+- These are **2 libs** (a demonstration that the pipeline produces calibrated significance),
+  not yet the full set of cited cells.
+
+## Reproduce
+```bash
+# WSL: bash sync_to_wsl.sh && bash preflight_clean.sh
+python baselines/sampling/repeat_runner.py --arch <arch> --provider openai --libs <lib> --reps 5 --out-dir <out>
+python baselines/sampling/stats_analyze.py --results-dir <out>
+```
diff --git a/commit0/baselines/sampling/repeat_runner.py b/commit0/baselines/sampling/repeat_runner.py
index 0f4cd5d..0f6f0c6 100644
--- a/commit0/baselines/sampling/repeat_runner.py
+++ b/commit0/baselines/sampling/repeat_runner.py
@@ -38,6 +38,11 @@ def runner_cmd(arch: str, provider: str, lib: str) -> list[str]:
     if arch == "single_shot":
         script = "run_lite_single_shot.py" if provider == "anthropic" else "run_lite_single_shot_openai.py"
         return [py, str(BASELINES / script), "--only", lib]
+    if arch == "kaizen_delta":
+        return [py, str(BASELINES / "run_lite_kaizen_delta.py"), "--provider", provider, "--only", lib]
+    if arch == "reflexion":
+        script = "run_lite_reflexion.py" if provider == "anthropic" else "run_lite_reflexion_openai.py"
+        return [py, str(BASELINES / script), "--only", lib]
     raise ValueError(f"unsupported arch for sampling scaffold: {arch}")
 
 def branch_of(arch: str, provider: str) -> str:
@@ -45,8 +50,26 @@ def branch_of(arch: str, provider: str) -> str:
         return f"{arch}_{provider}"                    # A1: per-provider branch (matches the fixed runners)
     if arch == "single_shot":
         return "single_shot_sonnet" if provider == "anthropic" else "single_shot_openai"
+    if arch == "reflexion":
+        return "reflexion_sonnet" if provider == "anthropic" else "reflexion_openai"
     raise ValueError(arch)
 
+def _cost_from_runner_json(d: dict, provider: str) -> float:
+    """cost_usd if recorded (>0), else compute from tokens (single_shot records tokens,
+    not totals.cost_usd). Mirrors value_add_fingerprint pricing so the valid-rep gate
+    doesn't discard a real run as 'billed nothing'."""
+    totals = d.get("totals") or {}
+    c = totals.get("cost_usd")
+    if c and float(c) > 0:
+        return float(c)
+    def g(key):
+        return float(totals.get(key, d.get(key, 0)) or 0)
+    inp, out, cached = g("input_tokens"), g("output_tokens"), g("cached_input_tokens")
+    if provider == "anthropic":
+        return (inp * 3 + out * 15) / 1_000_000
+    return ((inp - cached) * 1.25 + cached * 0.125 + out * 10) / 1_000_000
+
+
 def one_rep(arch, provider, lib, k, temperature, seed, dry, model=None, seed_key=None):
     """Run + score one rep. Returns the rep dict (or None on dry-run).
 
@@ -71,12 +94,15 @@ def one_rep(arch, provider, lib, k, temperature, seed, dry, model=None, seed_key
     # robust re-score of the branch the agent just produced (score_branch, not the
     # runner's own scoring) so every rep is scored identically (T1-T4).
     sc = sb.score_branch(lib, branch_of(arch, provider))
-    # cost from the runner's own JSON (it tracks the LLM spend)
+    # cost from the runner's own JSON. Some runners (single_shot) record TOKENS but not
+    # totals.cost_usd -> read cost_usd if present, else compute from tokens (mirrors
+    # value_add_fingerprint pricing). Otherwise a real run reads as $0 and the valid-rep
+    # gate (cost<=0) would wrongly discard it.
     runner_json = WORKSPACE / "baselines" / "results" / f"{lib}_{arch}_{provider}.json"
     cost = 0.0
     if runner_json.exists():
         try:
-            cost = float((json.loads(runner_json.read_text()).get("totals") or {}).get("cost_usd", 0) or 0)
+            cost = _cost_from_runner_json(json.loads(runner_json.read_text()), provider)
         except Exception:
             pass
     return {
@@ -141,7 +167,8 @@ def _fix_jinja_editable_install():
 
 def main():
     ap = argparse.ArgumentParser()
-    ap.add_argument("--arch", required=True, choices=["aider", "smolagents", "single_shot"])
+    ap.add_argument("--arch", required=True,
+                    choices=["aider", "smolagents", "single_shot", "kaizen_delta", "reflexion"])
     ap.add_argument("--provider", required=True, choices=["anthropic", "openai"])
     ap.add_argument("--libs", nargs="+", required=True)
     ap.add_argument("--reps", type=int, default=5)