route2: surface routed-fraction (frout) col + fix stale tau/hkgap legends

Audit (subagent, 2026-06-06) found no cheats and no math errors, but two
log-honesty gaps:
- tablelog tau/hkgap descriptions still described the deleted EMA-midpoint gate
  ("ema_hack_cos - ema_clean_cos", "calibrated route threshold"). Rewrote to the
  band semantics (tau=median live cos_b; hkgap=band width upper-lower).
- the spec's mandatory routed-mass gauge (mean f) was DEBUG-only. Promote it to
  the frout streaming column so the real-vs-random mass confound is checkable in
  the table (compare deploy-hack at matched frout), not just via qE.

Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>

src/vgrout/tablelog.py

@@ -133,14 +133,16 @@ class StepLogger:
                 _Col("cos_post",  6, "cout",  ".2f", "hack-ward fraction AFTER projection (want ~0: all removed)"),
                 _Col("fired",     5, "fired", ".2f",  "fraction of modules where projection fired"),
             ]
-        # route2: the routing gate is cos(g_b,v_grad) > tau, where tau is the
-        # per-step EMA midpoint of the hack vs clean cos clouds. Surface tau and
-        # the hack-clean gap so we can see the threshold ride the drift and whether
-        # the direction still separates (hkgap>0) -- replaces the silent cos>0 gate.
+        # route2: the routing gate is the pair-calibrated BAND. Per rollout,
+        # f = clamp((cos(g_b,v_grad) - lower)/(upper - lower), 0, 1) routes that
+        # fraction into the quarantine. lower/upper = mean clean/hack pair cosines.
+        # Surface where live cos sits (tau), the band width (hkgap), the routed
+        # fraction (frout, the mass gauge), and the post-routing leak (resid).
         if arm == "routing2":
             cols += [
-                _Col("tau",   6, "tau",   "+.2f", "per-step calibrated route threshold (midpoint of hack vs clean cos clouds)"),
-                _Col("hkgap", 6, "hkgap", "+.2f", "ema_hack_cos - ema_clean_cos; >0 = v_grad still separates hack from clean (else direction dead)"),
+                _Col("tau",   6, "tau",   "+.2f", "median live cos(g_b, v_grad); should sit inside the band [lower, upper]"),
+                _Col("hkgap", 6, "hkgap", "+.2f", "band width upper-lower (mean hack-pair minus clean-pair cosine); >0 = v_grad separates (else direction dead/random)"),
+                _Col("frout", 6, "frout", "+.2f", "mean routed fraction f over rollouts (the routed-mass gauge; compare real-vs-random at matched frout)"),
                 _Col("resid", 6, "resid", "+.2f", "cos(deployed delta_S.grad AFTER routing, v_grad); ~0 = hack stripped cleanly, >0 = leak into deployed knob"),
             ]
         if arm in ("routing", "routing2"):

src/vgrout/train.py

@@ -1267,10 +1267,10 @@ def main(cfg: Config) -> int:
             diag = {"mean_cos_pre": float("nan"), "mean_cos_post": float("nan"),
                     "frac_fired": float("nan"), "mean_cos_pre_s": float("nan"),
                     "mean_cos_pre_t": float("nan")}
-            # route2: report the mean per-module per-rollout flag rate so we can
-            # watch the mask actually fire (and rise as hacks emerge).
+            # route2: mean routed fraction f (mean over modules*prompts) -- also the
+            # frout streaming column; logged here too for the no-v_hack diag branch.
             if is_route2 and step_flagged:
-                logger.debug(f"route2 flagged frac (mean over modules*prompts): "
+                logger.debug(f"route2 routed frac f (mean over modules*prompts): "
                              f"{sum(step_flagged)/len(step_flagged):+.3f}")
         else:
             if split_this_step:
@@ -1581,6 +1581,7 @@ def main(cfg: Config) -> int:
             "q_egy": q_egy,
             "tau": (sum(step_tau) / len(step_tau)) if step_tau else float("nan"),
             "hkgap": (sum(step_hkgap) / len(step_hkgap)) if step_hkgap else float("nan"),
+            "frout": (sum(step_flagged) / len(step_flagged)) if step_flagged else float("nan"),
             "resid": (sum(step_resid) / len(step_resid)) if step_resid else float("nan"),
             "lr": sched.get_last_lr()[0],
             "cos_pre": diag["mean_cos_pre"],