DependencyTracker: only handle STORE_FAST for the GETTING_IMPORT status

[masenf]

STORE_FAST handling is not generally correct outside of the specific case of dealing with imports. So avoid resetting the stack or other issues when we're not importing.

[codspeed-hq]

CodSpeed Performance Report

Merging #6058 will not alter performance

_{Comparing masenf/dep-tracker-limit-import-scope (6d38f3b) with main (488a388)}

Summary

✅ 8 untouched

[greptile-apps]

Greptile Summary

Fixes incorrect STORE_FAST handling in the DependencyTracker by restricting it to import operations only.

• Added new GETTING_IMPORT status to track when processing import bytecode instructions
• Modified STORE_FAST handling to only apply when scan_status == ScanStatus.GETTING_IMPORT
• Prevents incorrect manipulation of tracked_locals when STORE_FAST is used for other purposes (e.g., storing nested functions)
• Added test case test_nested_function that verifies dependencies are tracked correctly when nested functions are present

The fix addresses a bug where any STORE_FAST instruction with a non-None top_of_stack would trigger import aliasing logic, even when storing non-import values like nested function definitions.

Confidence Score: 3/5

• This PR fixes an important bug but introduces another issue with missing state reset
• The fix correctly restricts STORE_FAST handling to import operations, preventing incorrect behavior with nested functions. However, the scan_status is not reset to SCANNING after handling the import STORE_FAST, which could cause subsequent STORE_FAST instructions to incorrectly trigger import handling logic. This follows the pattern used in _eval_get_state (line 309) where status is reset.
• Pay close attention to reflex/vars/dep_tracking.py - the missing scan_status reset on line 485 needs to be added

Important Files Changed

Filename	Overview
reflex/vars/dep_tracking.py	Added GETTING_IMPORT status and restricted STORE_FAST handling to imports only. Missing scan_status reset after STORE_FAST could cause state to persist incorrectly.
tests/units/vars/test_dep_tracking.py	Added test_nested_function to verify dependencies are tracked correctly in nested functions - validates the fix prevents incorrect STORE_FAST handling.

Sequence Diagram

sequenceDiagram
    participant Tracker as DependencyTracker
    participant Bytecode as Bytecode Instructions
    participant Status as scan_status
    participant Locals as tracked_locals

    Note over Tracker,Locals: Processing Import Statement
    Bytecode->>Tracker: IMPORT_NAME instruction
    Tracker->>Status: Set to GETTING_IMPORT
    Tracker->>Locals: Add module to tracked_locals
    Tracker->>Tracker: Set top_of_stack = module name
    
    Bytecode->>Tracker: STORE_FAST instruction
    Tracker->>Status: Check scan_status == GETTING_IMPORT?
    Status-->>Tracker: Yes
    Tracker->>Locals: Pop and reassign with alias
    Tracker->>Tracker: Reset top_of_stack = None
    Note over Tracker: BUG: scan_status not reset to SCANNING

    Note over Tracker,Locals: Processing Nested Function (After Fix)
    Bytecode->>Tracker: MAKE_FUNCTION instruction
    Bytecode->>Tracker: STORE_FAST instruction (for nested func)
    Tracker->>Status: Check scan_status == GETTING_IMPORT?
    Status-->>Tracker: No (if properly reset)
    Note over Tracker: STORE_FAST skipped - avoids incorrect handling

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[greptile-apps]

Additional Comments (1)

1. reflex/vars/dep_tracking.py, line 477-485 (link)

   logic: scan_status should be reset to ScanStatus.SCANNING after handling the STORE_FAST, similar to the pattern in _eval_get_state at line 309.

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