[Draft] Propagate cancellation to model and EP downloads by bmehta001 · Pull Request #674 · microsoft/Foundry-Local

bmehta001 · 2026-04-24T17:02:53Z

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Agent-Logs-Url: https://github.com/microsoft/Foundry-Local/sessions/21906197-0d60-44b4-b5e6-4698c0fecfe3 Co-authored-by: baijumeswani <12852605+baijumeswani@users.noreply.github.com>

…ovided Agent-Logs-Url: https://github.com/microsoft/Foundry-Local/sessions/21906197-0d60-44b4-b5e6-4698c0fecfe3 Co-authored-by: baijumeswani <12852605+baijumeswani@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

vercel · 2026-04-24T17:02:59Z

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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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Copilot · 2026-04-24T17:11:13Z

        try:
            self = ctypes.cast(self_ptr, ctypes.POINTER(ctypes.py_object)).contents.value

+            # Check for cancellation before processing the callback data.
+            if self._cancel_event is not None and self._cancel_event.is_set():
+                raise CancelledException("Operation cancelled")
+
            # convert to a string and pass to the python callback
            data_bytes = ctypes.string_at(data_ptr, length)
            data_str = data_bytes.decode('utf-8')
            self._py_callback(data_str)
            return 0  # continue
+        except CancelledException as e:
+            if self is not None and self.exception is None:
+                self.exception = e
+            return 1  # cancel


self may be referenced before assignment in the except CancelledException (and the generic except Exception) if an exception occurs before self = ctypes.cast(...) succeeds. Initialize self = None before the try, and then guard if self is not None safely in the exception handlers to avoid an UnboundLocalError masking the original failure/cancellation.

Copilot · 2026-04-24T17:11:14Z

+            user_cb = progress_callback if progress_callback is not None else lambda _pct: None
            response = self._core_interop.execute_command_with_callback(
                "download_model", request,
-                lambda pct_str: progress_callback(float(pct_str))
+                lambda pct_str: user_cb(float(pct_str)),
+                cancel_event,
            )


When cancel_event is provided without a progress_callback, this still attempts float(pct_str) for every chunk. If the native layer ever emits non-float chunks (e.g., whitespace-separated tokens, headers, or other status text), this will raise and fail the download unexpectedly. Consider making the callback parsing resilient (e.g., try/except ValueError to ignore non-float tokens, or splitting whitespace and parsing tokens similar to the Rust implementation).

Copilot · 2026-04-24T17:11:14Z

+            signal = namesOrCallbackOrSignal;
        } else {
-            names = namesOrCallback;
+            signal = maybeSignal;


The final else branch no longer preserves the old behavior where callers could pass (undefined, progressCallback) (or (undefined, signal)) and still have the second argument recognized. Previously, names would become undefined and progressCallback could still be taken from the second parameter; now progressCallbackOrSignal is ignored entirely in this branch. To avoid a backward-compat regression, handle this branch by interpreting progressCallbackOrSignal as either a progress callback or an AbortSignal when the first argument is undefined/missing.

Suggested change

signal = maybeSignal;

if (typeof progressCallbackOrSignal === 'function') {

progressCallback = progressCallbackOrSignal;

signal = maybeSignal;

} else if (isAbortSignal(progressCallbackOrSignal)) {

signal = progressCallbackOrSignal;

} else {

signal = maybeSignal;

}

Copilot · 2026-04-24T17:11:15Z

+        let cancelled = state.is_cancelled();
+
        // Flush any trailing partial UTF-8 bytes.
        state.flush();

+        if cancelled {
+            // Free native response memory before returning the error.
+            Self::process_response(response).ok();
+            return Err(FoundryLocalError::CommandExecution {
+                reason: "Operation cancelled".to_string(),
+            });
+        }


cancelled is derived from reading the shared AtomicBool after the native call returns. This can race: the flag may be set after the operation successfully completes but before this check runs, causing a spurious "Operation cancelled" error. A more robust approach is to track “cancellation was observed and requested during a callback” inside StreamingCallbackState (e.g., set a cancelled_observed field when the trampoline returns cancel) and only return a cancellation error when cancellation was actually acted upon during streaming.

Copilot AI and others added 4 commits April 22, 2026 16:56

Add download cancellation support across Python, JS/TS, and Rust SDKs

06705a2

Agent-Logs-Url: https://github.com/microsoft/Foundry-Local/sessions/21906197-0d60-44b4-b5e6-4698c0fecfe3 Co-authored-by: baijumeswani <12852605+baijumeswani@users.noreply.github.com>

Fix early return in EP download callback when only cancel_event is pr…

1da9f46

…ovided Agent-Logs-Url: https://github.com/microsoft/Foundry-Local/sessions/21906197-0d60-44b4-b5e6-4698c0fecfe3 Co-authored-by: baijumeswani <12852605+baijumeswani@users.noreply.github.com>

Complete SDK download cancellation support

f3226cd

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Clarify JS cancellation timing docs

b604a2e

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings April 24, 2026 17:02

Copilot AI reviewed Apr 24, 2026

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Copilot started reviewing on behalf of bmehta001 April 24, 2026 17:19 View session

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[Draft] Propagate cancellation to model and EP downloads#674

[Draft] Propagate cancellation to model and EP downloads#674
bmehta001 wants to merge 4 commits intomainfrom
bhamehta/sdk-download-cancellation

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