fix(media): validate upload paths before generation

[j15z]

Summary

Chat uploads can now be passed directly to media tools and to function_execute / run_code; callers no longer need to materialize an upload into files/ before using it. Explicit input and output declarations are validated before provider or FFmpeg work begins, and chat uploads are rejected if they do not belong to the active workspace.

Generated image, video, audio, and FFmpeg outputs keep their automatic files/... destinations when outputs is omitted. When an explicit destination is supplied, it must be a writable files/... path; create-mode writes retain automatic parent-folder creation.

Related: https://github.com/simstudioai/mothership/pull/352

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation
• Other: ___________

Testing

• 48 focused Vitest tests passed across sandbox upload mounting, image generation, media path resolution, and media-tool preflight behavior.
• GitHub's lint/test and application-build checks passed on the final head.
• Reviewers should focus on the uploads/ workspace boundary, explicit-output preflight ordering, and automatic-output fallbacks.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

Screenshots/Videos

Not applicable; this is server-side file resolution, validation, and sandbox-mounting behavior.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Jul 23, 2026 2:13am

[cursor]

PR Summary

Medium Risk
Changes touch copilot media execution, sandbox file mounting, and workspace/upload authorization; mistakes could block valid workflows or allow cross-workspace upload access, though tests cover the main boundaries.

Overview
Chat uploads as media inputs — Image, video, audio, and FFmpeg tools resolve uploads/... via resolveChatUpload (chat-scoped, workspace-checked) instead of treating uploads as unmountable or silently skipping missing references. Function execute mounts the same upload paths into the sandbox with presigned URLs when chatId is present.

Preflight path policy — New media/file-paths helpers require at least one input file when an inputs block is present, exactly one output when declared, reject uploads/ write targets, and run canonical workspace writer validation before Gemini, Fal, or FFmpeg runs.

Generated tool contracts — tool-catalog-v1 / tool-schemas-v1 document uploads in mount descriptions, add minItems / required: ['files'] on relevant input/output shapes, and cap single-file outputs with maxItems: 1 where applicable.

^{Reviewed by Cursor Bugbot for commit 3e1bdbc. Bugbot is set up for automated code reviews on this repo. Configure here.}

[greptile-apps]

Greptile Summary

This PR tightens media tool path handling for generated outputs and uploaded inputs. The main changes are:

• Shared validation for media input and output paths.
• Explicit output declarations for generated image, video, and audio tools.
• Chat-scoped uploads/... support for media inputs.
• Early output validation before Gemini, Fal, or FFmpeg work starts.
• ffmpeg probe behavior that skips unused output validation.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
apps/sim/lib/copilot/tools/server/media/file-paths.ts	Adds shared helpers for media input resolution and output validation.
apps/sim/lib/copilot/tools/server/media/ffmpeg.ts	Validates declared outputs before non-probe operations and lets probe return metadata without output validation.
apps/sim/lib/copilot/tools/server/image/generate-image.ts	Validates output paths before image generation and resolves declared reference files through the shared media helper.
apps/sim/lib/copilot/tools/server/media/generate-audio.ts	Validates output paths before audio generation and resolves an optional voice sample through the shared media helper.
apps/sim/lib/copilot/tools/server/media/generate-video.ts	Validates output paths before video generation and resolves an optional start-frame input through the shared media helper.
apps/sim/lib/copilot/generated/tool-catalog-v1.ts	Updates generated tool metadata for the new media input and output path boundary.
apps/sim/lib/copilot/generated/tool-schemas-v1.ts	Updates generated runtime schemas for explicit media outputs and constrained file declarations.

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[j15z]

@greptile

[j15z]

@cursor review

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[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 2 potential issues.

There are 5 total unresolved issues (including 3 from previous reviews).

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