fix(upstream): preserve source modality instead of flattening it

The generic provider computed modality as "text->text" for any vision model
and "text" otherwise, discarding the source's own modality and mislabelling
image-capable models. Carry OpenRouter's modality string through verbatim, and
when a source doesn't supply one, derive it from the captured input/output
modalities in the same "in->out" shape (e.g. "text+image->text").

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

routstr/upstream/generic.py

@@ -147,10 +147,13 @@ class GenericUpstreamProvider(BaseUpstreamProvider):
                     else:
                         enabled = True
 
-                    modality = (
-                        "text->text"
-                        if "image" in resolved.input_modalities
-                        else "text"
+                    # Prefer the source's own modality string (OpenRouter ships
+                    # one, e.g. "text+image->text"); otherwise derive it from the
+                    # captured input/output modalities in the same "in->out" shape
+                    # rather than flattening vision models to "text->text".
+                    modality = resolved.modality or (
+                        f"{'+'.join(resolved.input_modalities)}"
+                        f"->{'+'.join(resolved.output_modalities)}"
                     )
 
                     # A source can carry a price but no context (e.g. a litellm

routstr/upstream/pricing_resolver.py

@@ -31,6 +31,7 @@ class ResolvedPricing:
     completion: float
     context_length: int | None
     source: str
+    modality: str | None = None
     max_completion_tokens: int | None = None
     input_cache_read: float = 0.0
     input_cache_write: float = 0.0
@@ -159,6 +160,7 @@ def _from_openrouter(model_id: str, feed: list[dict]) -> ResolvedPricing | None:
         completion=completion,
         context_length=_as_int(entry.get("context_length")),
         source="openrouter",
+        modality=architecture.get("modality"),
         max_completion_tokens=_as_int(top_provider.get("max_completion_tokens")),
         input_cache_read=_as_float(pricing.get("input_cache_read")) or 0.0,
         input_cache_write=_as_float(pricing.get("input_cache_write")) or 0.0,

tests/unit/test_upstream_generic.py

@@ -104,6 +104,9 @@ async def test_native_model_spec_resolves_and_captures_metadata() -> None:
     assert model.pricing.completion == pytest.approx(1.5 / 1_000_000)
     assert model.context_length == 65536
     assert "image" in model.architecture.input_modalities
+    # Vision capability must be reflected in the combined modality string, not
+    # flattened to "text->text".
+    assert model.architecture.modality == "text+image->text"
     # A native price never needs the OpenRouter feed.
     or_feed.assert_not_awaited()
 
@@ -237,8 +240,8 @@ async def test_unknown_to_litellm_resolves_via_openrouter() -> None:
         "name": "Exotic 9000",
         "context_length": 65536,
         "architecture": {
-            "modality": "text->text",
-            "input_modalities": ["text"],
+            "modality": "text+image->text",
+            "input_modalities": ["text", "image"],
             "output_modalities": ["text"],
             "tokenizer": "Other",
             "instruct_type": None,
@@ -263,6 +266,8 @@ async def test_unknown_to_litellm_resolves_via_openrouter() -> None:
     assert model.pricing.prompt == pytest.approx(5e-06)
     assert model.pricing.completion == pytest.approx(1e-05)
     assert model.context_length == 65536
+    # The feed's own modality string is carried through verbatim, not recomputed.
+    assert model.architecture.modality == "text+image->text"
     or_feed.assert_awaited()