feat(virtualmodels): route image requests to vision-capable targets

[SantiagoDePolonia]

Part of #1104 (item 9).

Adds an opt-in vision_routing option to virtual models (config.yaml, VIRTUAL_MODELS, admin API, dashboard editor). When a request carries images (chat image_url, Responses input_image, Anthropic image blocks), only targets whose effective metadata reports vision are considered, before any strategy picks. Chained virtual models inherit the decision.

• If no target reports vision, routing is unchanged and the image is never stripped; unknown capability counts as text-only.
• Catalog entries listing image as an input modality now report the vision capability (an explicit flag still wins).
• The body is inspected only when an enabled virtual model opts in, so the default hot path is unchanged.
• Not included: failover legs after the first pick are not filtered.
• Overlaps fix(virtualmodels): skip disabled targets instead of failing the request #1137 in balancedResolution; whichever merges second needs a small rebase.

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📥 Commits

Reviewing files that changed from the base of the PR and between 37e293c and ac73779.

📒 Files selected for processing (31)

• cmd/gomodel/docs/docs.go
• config/config.example.yaml
• config/virtualmodels.go
• docs/advanced/model-metadata.mdx
• docs/features/virtual-models.mdx
• docs/openapi.json
• internal/admin/handler_virtualmodels.go
• internal/core/image_input.go
• internal/core/image_input_test.go
• internal/modeldata/merger.go
• internal/modeldata/merger_test.go
• internal/server/request_model_resolution.go
• internal/virtualmodels/balancer.go
• internal/virtualmodels/config.go
• internal/virtualmodels/resolve.go
• internal/virtualmodels/service.go
• internal/virtualmodels/snapshot.go
• internal/virtualmodels/store_mongodb.go
• internal/virtualmodels/store_sql.go
• internal/virtualmodels/types.go
• internal/virtualmodels/vision_test.go
• tests/e2e/vision_routing_test.go
• web/dashboard/messages/de.json
• web/dashboard/messages/en.json
• web/dashboard/messages/pl.json
• web/dashboard/messages/zh-CN.json
• web/dashboard/src/pages/models/VirtualModelEditor.svelte
• web/dashboard/src/pages/models/routing.js
• web/dashboard/src/pages/models/virtualModelEditor.svelte.js
• web/dashboard/src/pages/models/vmForm.js
• web/dashboard/tests/models-virtual-models.test.js

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Codecov Report

❌ Patch coverage is 91.89189% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/server/request_model_resolution.go	62.50%	3 Missing ⚠️
internal/virtualmodels/balancer.go	91.30%	2 Missing ⚠️
internal/core/image_input.go	95.83%	1 Missing ⚠️

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[greptile-apps]

Confidence Score: 4/5

[Medium risk] Adds image-aware routing to virtual model load balancing.

This PR is not ready to merge because provider-model metadata can make image routing skip an image-capable model.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[Request] --> B{Virtual model has vision routing?}
  B -- No --> E[Choose from viable targets]
  B -- Yes --> C{Body has an image?}
  C -- No --> E
  C -- Yes --> D[Keep targets reporting vision]
  D --> F{Any remain?}
  F -- No --> E
  F -- Yes --> G[Choose from vision targets]
  G --> H{Chained model?}
  H -- Yes --> D
  H -- No --> I[Send request]
  E --> I

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_{Reviews (1) · Last reviewed commit: "feat(virtualmodels): route image request..."}

[greptile-apps]

Vision flag gets lost

If a catalog model lists image as an input modality and its provider-model entry has a capabilities map without vision, buildMetadata replaces the map that held the derived vision flag. When another target reports vision, image routing skips this image-capable model. Keep the derived flag unless the provider explicitly sets vision.

[greptile-apps]

Saved vision setting disappears

Saving or toggling a single-target virtual model drops its existing vision_routing: true setting. Both payload builders send the flag only when there are multiple targets, though the server accepts it for one target. The setting stays off if the user adds another target later. Keep the saved flag in single-target payloads too.

[greptile-apps]

TREX

Could not complete testing for 1 flow, faced 1 obstacle.

Obstacles faced

• No config-managed virtual model exists; add a disposable one to check its read-only setting.

_{To reduce obstacles, configure your TREX environment.}

What we tested

• Incomplete — Vision routing setting in virtual models ▶