Re-apply #4939: updated models template mappers (#4950)

* Reapply "updated models template mappers. added lfm2.5vl450m to transformers 5…" (#4945)

This reverts commit 33503ea248.

* Add missing gemma-4-31B-it bnb-4bit mapper entry and LFM2.5 upstream namespace for PR #4950

- Add unsloth/gemma-4-31B-it-unsloth-bnb-4bit to __INT_TO_FLOAT_MAPPER so
  the int-to-float resolution works for this model (already listed in
  TEMPLATE_TO_MODEL_MAPPER but had no mapper entry).
- Add LiquidAI/LFM2.5-1.2B-Instruct to lfm-2.5 TEMPLATE_TO_MODEL_MAPPER
  entry so the canonical upstream namespace is mapped consistently with lfm-2.

* Add missing gemma-4-31B-it bnb-4bit Ollama mapping and lfm-2.5 chat template alias

- Add unsloth/gemma-4-31B-it-unsloth-bnb-4bit to OLLAMA_TEMPLATE_TO_MODEL_MAPPER
  so Ollama export works for this model (E2B-it and E4B-it bnb-4bit variants were
  already present, 31B-it was inconsistently omitted)
- Register CHAT_TEMPLATES["lfm-2.5"] as alias of the lfm-2 template to prevent
  KeyError when Studio resolves LFM2.5 models through MODEL_TO_TEMPLATE_MAPPER

* Add missing LFM2 bnb-4bit INT_TO_FLOAT_MAPPER entry

unsloth/LFM2-1.2B-unsloth-bnb-4bit is referenced in model_mappings.py
but had no mapper.py entry, so model resolution would fail when users
load that variant with load_in_4bit=False or when the float name is
used with load_in_4bit=True.

* Fix review findings for PR #16

1. ollama_template_mappers.py: Restore dropped Gemma-4 base model IDs
   (E2B, E4B, 31B, 26B-A4B) and add missing google/ upstream IDs to
   the gemma4 Ollama mapper for consistency with other gemma entries.

2. mapper.py: Remove self-mapping non-bnb-4bit entries from
   __INT_TO_FLOAT_MAPPER that were polluting FLOAT_TO_INT_MAPPER with
   lowercase 16-bit names, causing load_in_4bit=True to return bad
   model names. Add direct MAP_TO_UNSLOTH_16bit entries to preserve
   the google->unsloth 16-bit redirects.

3. mapper.py: Add LFM2.5 MAP_TO_UNSLOTH_16bit redirect so
   LiquidAI/LFM2.5-1.2B-Instruct resolves to its unsloth mirror.

* Add review tests for PR #4950

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Remove top-level test files

These test_*.py files were added at the repo root rather than under tests/.
Removing them from this PR; the production mapper changes remain.

* Add gemma-4-26B-A4B-it mapping

Adds unsloth/gemma-4-26B-A4B-it to __INT_TO_FLOAT_MAPPER as a 2-tuple so
google/gemma-4-26B-A4B-it routes to unsloth/gemma-4-26B-A4B-it across
INT_TO_FLOAT_MAPPER, FLOAT_TO_INT_MAPPER, and MAP_TO_UNSLOTH_16bit.

The 26B-A4B (MoE) model has no bnb-4bit variant, so the key uses the
plain unsloth name rather than the -unsloth-bnb-4bit suffix.

Removes the now-redundant standalone _add_with_lower call for the -it
variant; the 16bit mapping is registered via the dict loop.

* Add unsloth-bnb-4bit mappings for gemma-4 base (non-it) models

Adds E2B, E4B, 31B base unsloth-bnb-4bit entries to __INT_TO_FLOAT_MAPPER.
The 26B-A4B (MoE) base has no bnb-4bit variant on HF, so it stays on the
standalone _add_with_lower line for the 16bit-only routing.

Removes the redundant _add_with_lower lines for E2B, E4B, 31B base since
the dict loop now registers the same google->unsloth route through the
2-tuple entries, plus full FLOAT_TO_INT and INT_TO_FLOAT coverage.

---------

Co-authored-by: Daniel Han <danielhanchen@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

studio/backend/utils/datasets/model_mappings.py

@@ -215,6 +215,21 @@ TEMPLATE_TO_MODEL_MAPPER = {
         "google/gemma-3n-E2B-it",
         "unsloth/gemma-3n-E2B-it-unsloth-bnb-4bit",
     ),
+    "gemma-4": (
+        "unsloth/gemma-4-E2B-it",
+        "google/gemma-4-E2B-it",
+        "unsloth/gemma-4-E4B-it",
+        "google/gemma-4-E4B-it",
+        "unsloth/gemma-4-E2B-it-unsloth-bnb-4bit",
+        "unsloth/gemma-4-E4B-it-unsloth-bnb-4bit",
+    ),
+    "gemma-4-thinking": (
+        "unsloth/gemma-4-26B-A4B-it",
+        "google/gemma-4-26B-A4B-it",
+        "unsloth/gemma-4-31B-it",
+        "unsloth/gemma-4-31B-it-unsloth-bnb-4bit",
+        "google/gemma-4-31B-it",
+    ),
     "qwen2.5": (
         "unsloth/Qwen2.5-0.5B-Instruct-unsloth-bnb-4bit",
         "unsloth/Qwen2.5-0.5B-Instruct",
@@ -399,6 +414,15 @@ TEMPLATE_TO_MODEL_MAPPER = {
         "THUDM/GLM-4.7-Flash",
         "unsloth/GLM-4.7-Flash-bnb-4bit",
     ),
+    "lfm-2": (
+        "unsloth/LFM2-1.2B",
+        "LiquidAI/LFM2-1.2B",
+        "unsloth/LFM2-1.2B-unsloth-bnb-4bit",
+    ),
+    "lfm-2.5": (
+        "unsloth/LFM2.5-1.2B-Instruct",
+        "LiquidAI/LFM2.5-1.2B-Instruct",
+    ),
 }
 
 MODEL_TO_TEMPLATE_MAPPER = {}
@@ -414,6 +438,14 @@ for key, values in TEMPLATE_TO_MODEL_MAPPER.items():
 
 
 TEMPLATE_TO_RESPONSES_MAPPER = {
+    "gemma-4-thinking": {
+        "instruction": "<|turn>user\n",
+        "response": "<|turn>model\n",
+    },
+    "gemma-4": {
+        "instruction": "<|turn>user\n",
+        "response": "<|turn>model\n",
+    },
     "gemma-3": {
         "instruction": "<start_of_turn>user\n",
         "response": "<start_of_turn>model\n",
@@ -514,6 +546,10 @@ TEMPLATE_TO_RESPONSES_MAPPER = {
         "instruction": "<|im_start|>user\n",
         "response": "<|im_start|>assistant\n",
     },
+    "lfm-2.5": {
+        "instruction": "<|im_start|>user\n",
+        "response": "<|im_start|>assistant\n",
+    },
     "starling": {
         "instruction": "GPT4 Correct User: ",
         "response": "GPT4 Correct Assistant: ",

studio/backend/utils/transformers_version.py

@@ -52,6 +52,7 @@ TRANSFORMERS_5_MODEL_SUBSTRINGS: tuple[str, ...] = (
     "qwen3.5",  # Qwen3.5 family (35B-A3B, etc.)
     "qwen3-next",  # Qwen3-Next and variants
     "tiny_qwen3_moe",  # imdatta0/tiny_qwen3_moe_2.8B_0.7B
+    "lfm2.5-vl-450m",  # LiquidAI/LFM2.5-VL-450M
 )
 
 # Lowercase substrings for models that require transformers 5.5.0 (checked first).

unsloth/chat_templates.py

@@ -1716,6 +1716,8 @@ liquid_lfm2_template = \
 liquid_lfm2_template_eos_token = "<|im_end|>"
 CHAT_TEMPLATES["lfm-2"] = (liquid_lfm2_template, liquid_lfm2_template_eos_token, False, None)
 DEFAULT_SYSTEM_MESSAGE["lfm-2"] = None # No system message in Phi-3
+CHAT_TEMPLATES["lfm-2.5"] = (liquid_lfm2_template, liquid_lfm2_template_eos_token, False, None)
+DEFAULT_SYSTEM_MESSAGE["lfm-2.5"] = None
 
 
 # =========================================== Starling-LM

unsloth/models/mapper.py

@@ -22,6 +22,39 @@ __all__ = [
 
 __INT_TO_FLOAT_MAPPER = \
 {
+    "unsloth/gemma-4-E2B-it-unsloth-bnb-4bit" : (
+        "unsloth/gemma-4-E2B-it",
+        "google/gemma-4-E2B-it",
+    ),
+    "unsloth/gemma-4-E4B-it-unsloth-bnb-4bit" : (
+        "unsloth/gemma-4-E4B-it",
+        "google/gemma-4-E4B-it",
+    ),
+    "unsloth/gemma-4-31B-it-unsloth-bnb-4bit" : (
+        "unsloth/gemma-4-31B-it",
+        "google/gemma-4-31B-it",
+    ),
+    "unsloth/gemma-4-26B-A4B-it" : (
+        "unsloth/gemma-4-26B-A4B-it",
+        "google/gemma-4-26B-A4B-it",
+    ),
+    "unsloth/gemma-4-E2B-unsloth-bnb-4bit" : (
+        "unsloth/gemma-4-E2B",
+        "google/gemma-4-E2B",
+    ),
+    "unsloth/gemma-4-E4B-unsloth-bnb-4bit" : (
+        "unsloth/gemma-4-E4B",
+        "google/gemma-4-E4B",
+    ),
+    "unsloth/gemma-4-31B-unsloth-bnb-4bit" : (
+        "unsloth/gemma-4-31B",
+        "google/gemma-4-31B",
+    ),
+    "unsloth/LFM2-1.2B-unsloth-bnb-4bit" : (
+        "unsloth/LFM2-1.2B",
+        "LiquidAI/LFM2-1.2B",
+    ),
+
     "unsloth/mistral-7b-bnb-4bit" : (
         "unsloth/mistral-7b",
         "mistralai/Mistral-7B-v0.1",
@@ -1428,3 +1461,6 @@ for key, values in __INT_TO_FLOAT_MAPPER.items():
 
     for value in values:
         FLOAT_TO_INT_MAPPER[value.lower()] = lowered_key
+
+_add_with_lower(MAP_TO_UNSLOTH_16bit, "google/gemma-4-26B-A4B", "unsloth/gemma-4-26B-A4B")
+_add_with_lower(MAP_TO_UNSLOTH_16bit, "LiquidAI/LFM2.5-1.2B-Instruct", "unsloth/LFM2.5-1.2B-Instruct")

unsloth/ollama_template_mappers.py

@@ -1978,12 +1978,19 @@ OLLAMA_TEMPLATE_TO_MODEL_MAPPER = {
     ),
     "gemma4": (
         "unsloth/gemma-4-E2B-it",
+        "unsloth/gemma-4-E2B-it-unsloth-bnb-4bit",
+        "google/gemma-4-E2B-it",
         "unsloth/gemma-4-E2B",
         "unsloth/gemma-4-E4B-it",
+        "unsloth/gemma-4-E4B-it-unsloth-bnb-4bit",
+        "google/gemma-4-E4B-it",
         "unsloth/gemma-4-E4B",
         "unsloth/gemma-4-31B-it",
+        "unsloth/gemma-4-31B-it-unsloth-bnb-4bit",
+        "google/gemma-4-31B-it",
         "unsloth/gemma-4-31B",
         "unsloth/gemma-4-26B-A4B-it",
+        "google/gemma-4-26B-A4B-it",
         "unsloth/gemma-4-26B-A4B",
     ),
     "gemma3n": (