Decode a data: URIContent to Gemini InlineData instead of passing it as FileData.FileURI

[PratikDhanave (PratikDhanave)]

What

In provider/geminiprovider/agent.go, the *message.URIContent arm of buildRequestParts emitted the URI unconditionally as FileData.FileURI. A data: URI is a perfectly valid URIContent value (validateURIContentURI only requires IsAbs(), and url.Parse of a data: URI yields Scheme=data, so IsAbs() is true), so it flowed down this path.

Gemini's file_data.file_uri requires an external reference (gs:// or http(s)://); a data:image/...;base64,... string is not a valid file URI, so Gemini rejects/ignores it and the multimodal input is silently dropped.

This change branches on the URI scheme in the URIContent arm:

• data: URIs are decoded (media type + bytes) and emitted as InlineData, mirroring the existing DataContent arm directly above.
• True external URIs (gs://, http(s)://) keep the existing FileData mapping.

It adds a small exported message.DecodeDataURI helper that reuses the package's existing RFC 2397 parser, so both base64 and percent-encoded payloads are handled correctly instead of hand-rolling a parse.

Why (cross-SDK parity)

This matches the Python reference, which uses from_bytes for data: URIs and from_uri otherwise. It is also the Gemini analogue of the same fix already applied for the other providers: #667 (openai-chat), #615 (anthropic), #559 (openai). Gemini was never given this handling.

Tests

TestDataURIContentInRequest in provider/geminiprovider/agent_test.go drives the exported Run API through the existing fake-transport harness and asserts:

• a URIContent with data:image/png;base64,... produces a part with inlineData (correct mimeType and decoded data) and no fileData;
• a companion https://example.com/x.png case still maps to fileData.fileUri.

The test fails before the fix (the data URI is sent as fileData.fileUri) and passes after. go build ./..., go vet, and go test for the geminiprovider and message packages are green.

[Copilot]

Pull request overview

This PR fixes Gemini multimodal request construction so that data: URIs carried via *message.URIContent are decoded and sent as inlineData (instead of incorrectly being forwarded as fileData.fileUri, which Gemini expects to be an external URI).

Changes:

• Update Gemini request-part building to branch on URIContent.URI scheme and decode data: URIs into InlineData.
• Add an exported message.DecodeDataURI helper built on the existing RFC 2397 parser.
• Add a Gemini provider test to assert data: URIs become inlineData and external URIs remain fileData.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
provider/geminiprovider/agent.go	Decode data: URIContent into InlineData instead of sending as FileData.FileURI.
provider/geminiprovider/agent_test.go	Add coverage to ensure data: URIs map to inlineData and external URIs map to fileData.
message/datauri.go	Export DecodeDataURI to decode RFC2397 data: URIs for provider use.

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[github-actions]

Cross-SDK Parity Review — Approved

PR: Decode data: URIContent to Gemini InlineData instead of passing it as FileData.FileURI

Scope

4 files changed:

• provider/geminiprovider/agent.go — bug fix: branch on URI scheme in URIContent arm of buildRequestParts
• message/datauri.go — new exported helper DecodeDataURI
• provider/geminiprovider/agent_test.go — TestDataURIContentInRequest

Parity Assessment

Python upstream (python/packages/gemini/agent_framework_gemini/_chat_client.py):

The Python implementation checks uri.startswith("(redacted) and uses types.Part.from_bytes for data URIs vs types.Part.from_uri for external ones. The Go implementation does exactly the same: data: URIs become InlineData blobs, external URIs ((redacted) https://, ...) become FileData. Both use the content MediaType when set and fall back to the parsed media type from the URI for data: URIs.

.NET: No Gemini provider was found in dotnet/src/; the fix is Go/Python only, no .NET divergence applies.

New Public API

message.DecodeDataURI(uri string) ([]byte, string, error) — thin, well-scoped RFC 2397 helper reusing the package existing internal parser. Concept is aligned with Pythons _get_data_bytes + from_bytes pattern. No cross-SDK divergence.

Verdict

This change brings the Gemini provider into parity with the Python SDK and mirrors analogous fixes already applied for other providers (#667, #615, #559). Labels public-api-change and parity-approved are both correct and retained.

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