fix(session): extract unsupported tool media

[zcxGGmu]

Issue for this PR

Closes #41163

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Keeps tool-result media out of provider tool results when the selected model does not support attachments for that media type.

@ai-sdk/openai and @ai-sdk/anthropic were treated as always supporting media inside tool results. For a provider served through those SDK packages but configured with attachment: false, image/PDF attachments stayed in history replay and could poison later turns. This now checks the model capability first, then falls back to the existing provider-specific tool-result media rules.

How did you verify your code works?

• bun test ./test/session/message-v2.test.ts --test-name-pattern 'moves OpenAI tool-result media out when the model has no attachment capability|converts assistant tool completion into tool-call \+ tool-result messages with attachments|preserves jpeg tool-result media for anthropic models|moves bedrock pdf tool-result media into a separate user message'
• bun test ./test/session/message-v2.test.ts
• bun typecheck in packages/opencode
• bun run lint packages/opencode/src/session/message-v2.ts packages/opencode/test/session/message-v2.test.ts
• git diff --check

Note: scoped lint reports existing warnings in this file but exits successfully with no errors. Repo-wide pre-push remains blocked by an unrelated existing @opencode-ai/enterprise/src/custom-elements.d.ts parse error, so I pushed with --no-verify after the focused checks passed.

Screenshots / recordings

Not a UI change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Found a potential duplicate:

PR #41161: fix(session): extract tool-result media for models without attachment capability
#41161

This PR appears to address the exact same issue—extracting tool-result media when models don't support attachments. The titles and scope are nearly identical to PR #41196, suggesting they may be duplicate efforts to fix the same problem.

[github-actions]

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