Propagate cancellation to model and EP downloads

[bmehta001]

Adds cancellation support for SDK model and execution provider downloads across C#, Python, JavaScript/TypeScript, Rust, and C++.

• Cancellation is wired through the existing native streaming callback path so downloads can be interrupted at the next native progress/callback boundary while preserving the existing non-streaming fast path when no progress callback or cancellation token/signal is supplied.

Changes

• Added cancellable model download APIs across SDKs:
  • C#: CancellationToken
  • Python: cancellation event
  • JS/TS: AbortSignal, including model.download(signal)
  • Rust: Arc<AtomicBool>
  • C++: CancellationCallback
• Preserved existing progress callback behavior and added cancellation support alongside progress callbacks.
• Kept fast paths for downloads that do not request progress or cancellation.
• Hardened callback handling:
  • Avoids converting successful operations into cancellation when cancellation is requested after the final observed callback.
  • Ensures native response buffers are cleaned up before surfacing cancellation/errors.
  • Avoids flushing buffered partial streaming data after cancellation.
• Improved mixed progress parsing so status text and numeric progress chunks are handled consistently.
• Updated SDK docs and samples

Validation

• Added cancellation/progress parsing tests for C#, Python, JS, Rust

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Project	Deployment	Actions	Updated (UTC)
foundry-local	Ready	Preview, Comment	May 14, 2026 4:03am

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR adds download cancellation support across SDKs by routing model and EP downloads through streaming/callback interop when a cancellation signal/token/flag is supplied, and documenting the new behavior.

Changes:

• Rust: add cancellable variants of model/EP download APIs and cancellable streaming interop in CoreInterop.
• Python/JS/C#: add cancellation parameters (Event/AbortSignal/CancellationToken) and ensure downloads use callback/streaming paths to observe cancellation.
• Docs/tests: document cancellation usage and add unit tests verifying the callback/streaming path is used when cancellation is provided.

Reviewed changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
sdk/rust/src/foundry_local_manager.rs	Adds cancellable EP download APIs and routes to cancellable streaming interop.
sdk/rust/src/detail/model_variant.rs	Adds cancellable model variant download path via cancellable streaming interop.
sdk/rust/src/detail/model.rs	Exposes cancellable model download API.
sdk/rust/src/detail/core_interop.rs	Adds cancellable streaming interop and cancellation checks in the FFI callback trampoline.
sdk/rust/README.md	Documents Rust cancellation usage for downloads.
sdk/python/test/test_model.py	Adds a test ensuring model download uses callback path when cancel_event is provided.
sdk/python/test/test_foundry_local_manager.py	Adds a test ensuring EP download uses callback path when cancel_event is provided.
sdk/python/src/imodel.py	Extends download() interface with optional cancel_event.
sdk/python/src/foundry_local_manager.py	Adds cancel_event support and routes through callback interop when provided.
sdk/python/src/detail/model_variant.py	Adds cancel_event support and routes through callback interop when provided.
sdk/python/src/detail/model.py	Plumbs cancel_event through Model.download() to the selected variant.
sdk/python/src/detail/core_interop.py	Adds cancellation support to callback helper and raises on cancellation.
sdk/python/README.md	Documents Python cancellation usage for downloads.
sdk/js/test/model.test.ts	Adds a test ensuring model download uses streaming interop when only AbortSignal is provided.
sdk/js/test/foundryLocalManager.test.ts	Adds a test ensuring EP download passes AbortSignal through to streaming interop.
sdk/js/src/imodel.ts	Extends download() interface with optional AbortSignal.
sdk/js/src/foundryLocalManager.ts	Adds AbortSignal overloads and passes signal to streaming interop.
sdk/js/src/detail/modelVariant.ts	Routes model download to streaming when progress or cancellation is needed.
sdk/js/src/detail/model.ts	Plumbs AbortSignal through Model.download() to the selected variant.
sdk/js/src/detail/coreInterop.ts	Adds AbortSignal-aware streaming wrapper that rejects with AbortError on cancellation.
sdk/js/README.md	Documents JS cancellation usage for downloads.
sdk/cs/test/FoundryLocal.Tests/Utils.cs	Improves repo-root discovery to handle .git files (worktrees/submodules).
sdk/cs/test/FoundryLocal.Tests/DownloadCancellationTests.cs	Adds a test covering cancellation propagation via callback path in model download.
sdk/cs/src/FoundryLocalManager.cs	Routes EP download through callback path when cancellation is possible; checks token in callback.
sdk/cs/src/Detail/ModelVariant.cs	Routes model download through callback path when cancellation is possible; checks token in callback.
sdk/cs/src/Detail/CoreInterop.cs	Preserves OperationCanceledException propagation from callback execution.
sdk/cs/README.md	Documents C# cancellation usage for downloads.

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Pull request overview

Copilot reviewed 41 out of 41 changed files in this pull request and generated 4 comments.

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