Manuscript revision and pending experiment work, snapshot before restructuring

Clarity pass over the main text (36-item audit), Discussion rewrite and cut,
acknowledgements, Souly et al. as ref 62, lettered SI panels, model section
moved under Results; plus the untracked curriculum/society/compose/smol
configs, runners, figures, stats and tests that the SI already cites.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y64o8FKP7rCuXzC48pxpMm

figures/_figlib.py

@@ -21,6 +21,28 @@ def load_bundle(results_dir: str | Path) -> tuple[pd.DataFrame, dict]:
     return df, resolved["source_config"]
 
 
+def load_seed_bundles(results_dir: str | Path) -> tuple[pd.DataFrame, dict]:
+    """Load a per-seed bundle layout ``results_dir/s{seed}/results.parquet`` into one frame.
+
+    Each sub-bundle gets a ``seed`` column from its directory name (the HPC array-job layout, one
+    element per seed). A flat single-seed bundle is accepted too, tagged with its manifest seed.
+    Returns (frame, source config of the first seed).
+    """
+    results_dir = Path(results_dir)
+    subs = sorted(results_dir.glob("s[0-9]*/results.parquet"))
+    if not subs:
+        df, cfg = load_bundle(results_dir)
+        if "seed" not in df.columns:
+            df = df.assign(seed=int(cfg.get("seed", 1)))
+        return df, cfg
+    frames, cfg0 = [], None
+    for p in subs:
+        df, cfg = load_bundle(p.parent)
+        cfg0 = cfg0 or cfg
+        frames.append(df.assign(seed=int(p.parent.name[1:])))
+    return pd.concat(frames, ignore_index=True), cfg0
+
+
 def mean_ci(df: pd.DataFrame, by: str, value: str, ci: float = 0.95):
     """Return (index, mean, half-width) for a normal-approx CI of ``value`` grouped by ``by``."""
     from scipy import stats
@@ -38,3 +60,23 @@ def savefig(fig, results_dir: str | Path, name: str) -> None:
     fig.savefig(results_dir / f"{name}.png", dpi=150, bbox_inches="tight")
     fig.savefig(results_dir / f"{name}.pdf", bbox_inches="tight")
     print(f"wrote {results_dir}/{name}.png and .pdf")
+
+
+def letter_axes(fig, x: float = -0.1, y: float = 1.04, fontsize: float = 13) -> None:
+    """Letter every data axes of ``fig`` A, B, C ... in reading order (top row first, left to right).
+
+    Twin axes and colourbars share a frame with a lettered axes and are skipped. Call once, after
+    every axes exists and before saving.
+    """
+    seen: list[tuple[float, float]] = []
+    axes = []
+    for ax in fig.axes:
+        b = ax.get_position()
+        key = (round(b.x0, 3), round(b.y0, 3))
+        if key in seen or b.width < 0.05:            # twin axes / colourbars
+            continue
+        seen.append(key); axes.append(ax)
+    axes.sort(key=lambda a: (-round(a.get_position().y0, 2), a.get_position().x0))
+    for i, ax in enumerate(axes):
+        ax.text(x, y, chr(ord("A") + i), transform=ax.transAxes, fontsize=fontsize, fontweight="bold",
+                va="bottom", ha="left", clip_on=False)