Add gumbel/learn_centers/learn_width/learn_temperature to out-dir naming

Extends default_out_dir_name's non-default-field convention to the
router's new gumbel combine-weight flag and its learnable-knob toggles,
so gumbel sweep configs (learn_centers on/off, learn_width,
learn_temperature) resolve to distinguishable checkpoint directory
names instead of colliding on the same r-<type><n> token.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

giant/config.py

@@ -339,6 +339,29 @@ def _router_candidate(train, model):
     return f"r-{router['type']}{router['n_experts']}"
 
 
+def _router_flag_candidate(field, token_map):
+    """Candidate factory for a boolean `model.router` sub-field.
+
+    Gated on `router.enabled` like `_router_candidate` (a disabled router's
+    sub-fields are meaningless), then omitted unless `field` differs from
+    its DEFAULT_CONFIG value — same "only show non-default" rule as every
+    other candidate. `token_map` need only cover the non-default value(s),
+    since the default value always yields None.
+    """
+
+    def _candidate(train, model):
+        router = model["router"]
+        default_router = DEFAULT_CONFIG["model"]["router"]
+        if router["enabled"] == default_router["enabled"]:
+            return None
+        value = router[field]
+        if value == default_router[field]:
+            return None
+        return token_map[value]
+
+    return _candidate
+
+
 def _conditioning_candidate(train, model):
     if model["conditioning"] == DEFAULT_CONFIG["model"]["conditioning"]:
         return None
@@ -360,6 +383,10 @@ def _default_field_candidate(section_key, field, prefix):
 _OUT_DIR_NAME_CANDIDATES = [
     ("mode", _mode_candidate),
     ("router", _router_candidate),
+    ("gumbel", _router_flag_candidate("gumbel", {True: "gum"})),
+    ("learn_centers", _router_flag_candidate("learn_centers", {False: "nolc"})),
+    ("learn_width", _router_flag_candidate("learn_width", {True: "lw"})),
+    ("learn_temperature", _router_flag_candidate("learn_temperature", {True: "lt"})),
     ("conditioning", _conditioning_candidate),
     ("hidden_dim", _default_field_candidate("model", "hidden_dim", "h")),
     ("n_blocks", _default_field_candidate("model", "n_blocks", "b")),

tests/test_config.py

@@ -207,6 +207,64 @@ def test_default_out_dir_name_router_disabled_omitted_even_if_subfields_nondefau
     assert gconfig.default_out_dir_name(cfg, now=_NOW) == "20260729_1430"
 
 
+def test_default_out_dir_name_router_gumbel_shown_when_enabled():
+    cfg = _default_cfg(
+        router={"enabled": True, "type": "energy", "n_experts": 8, "gumbel": True}
+    )
+    assert gconfig.default_out_dir_name(cfg, now=_NOW) == "20260729_1430_r-energy8_gum"
+
+
+def test_default_out_dir_name_router_gumbel_omitted_when_router_disabled():
+    cfg = _default_cfg(
+        router={"enabled": False, "type": "energy", "n_experts": 8, "gumbel": True}
+    )
+    assert gconfig.default_out_dir_name(cfg, now=_NOW) == "20260729_1430"
+
+
+def test_default_out_dir_name_router_learn_centers_shown_only_when_disabled():
+    cfg_default = _default_cfg(
+        router={"enabled": True, "type": "energy", "n_experts": 8}
+    )
+    assert (
+        gconfig.default_out_dir_name(cfg_default, now=_NOW) == "20260729_1430_r-energy8"
+    )
+
+    cfg_off = _default_cfg(
+        router={
+            "enabled": True,
+            "type": "energy",
+            "n_experts": 8,
+            "learn_centers": False,
+        }
+    )
+    assert (
+        gconfig.default_out_dir_name(cfg_off, now=_NOW)
+        == "20260729_1430_r-energy8_nolc"
+    )
+
+
+def test_default_out_dir_name_router_learn_width_and_temperature_shown():
+    cfg = _default_cfg(
+        router={
+            "enabled": True,
+            "type": "energy",
+            "n_experts": 8,
+            "learn_width": True,
+        }
+    )
+    assert gconfig.default_out_dir_name(cfg, now=_NOW) == "20260729_1430_r-energy8_lw"
+
+    cfg2 = _default_cfg(
+        router={
+            "enabled": True,
+            "type": "energy",
+            "n_experts": 8,
+            "learn_temperature": True,
+        }
+    )
+    assert gconfig.default_out_dir_name(cfg2, now=_NOW) == "20260729_1430_r-energy8_lt"
+
+
 def test_default_out_dir_name_mode_shown_bare_no_prefix():
     cfg = _default_cfg(mode="wgan")
     assert gconfig.default_out_dir_name(cfg, now=_NOW) == "20260729_1430_wgan"