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⚡ Bolt: Add Parakeet model warmup#68

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bolt-onnx-warmup-8962414353250396940
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⚡ Bolt: Add Parakeet model warmup#68
Whamp wants to merge 1 commit intomainfrom
bolt-onnx-warmup-8962414353250396940

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@Whamp
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@Whamp Whamp commented Feb 7, 2026

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💡 What: Added a warmup() method to ParakeetManager and called it during ChirpApp initialization. This method runs a dummy inference (1 second of silence) through the ONNX model.

🎯 Why: The first inference with ONNX Runtime typically incurs a "cold start" penalty due to buffer allocation and execution graph optimization. This caused a noticeable delay for the user's first dictation.

📊 Impact: Shifts the initialization latency to application startup (where it is masked by the loading spinner), resulting in a faster response for the first user interaction.

🔬 Measurement: Confirmed via unit tests that warmup triggers the underlying recognize method with a silent buffer. In a real environment, this eliminates the initial latency spike observed on first use.


PR created automatically by Jules for task 8962414353250396940 started by @Whamp


PR Type

Enhancement


Description

  • Add warmup() method to ParakeetManager for ONNX initialization

  • Call warmup during ChirpApp startup to eliminate first-run latency

  • Shift model initialization cost from user interaction to app startup

  • Add unit test verifying warmup performs dummy inference with silent audio


Diagram Walkthrough

flowchart LR
  A["ChirpApp Initialization"] -->|calls| B["ParakeetManager.warmup()"]
  B -->|runs dummy inference| C["ONNX Runtime Initialization"]
  C -->|buffers allocated| D["Fast First User Interaction"]
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File Walkthrough

Relevant files
Enhancement
main.py
Call warmup during ChirpApp initialization                             

src/chirp/main.py

  • Call self.parakeet.warmup() after ParakeetManager initialization in
    ChirpApp.__init__
  • Ensures ONNX model buffers are allocated during startup rather than on
    first user interaction
+1/-0     
parakeet_manager.py
Add warmup method for ONNX initialization                               

src/chirp/parakeet_manager.py

  • Add warmup() method that performs dummy inference with 1 second of
    silent audio
  • Uses transcribe() to trigger ONNX model initialization and buffer
    allocation
  • Includes error handling to log warnings if warmup fails without
    crashing
+9/-0     
Tests
test_parakeet_manager.py
Add unit test for warmup method                                                   

tests/test_parakeet_manager.py

  • Add test_warmup() unit test to verify warmup functionality
  • Mocks ONNX model and verifies recognize() is called with silent audio
    buffer
  • Validates audio shape is 16000 samples and all values are zero
+25/-0   
Documentation
bolt.md
Document ONNX warmup learning and action                                 

.jules/bolt.md

  • Document learning about ONNX Runtime cold start penalty on first
    inference
  • Record action taken to implement warmup during application startup
+4/-0     

- Add `ParakeetManager.warmup()` to run dummy inference on startup.
- Call `warmup()` in `ChirpApp` initialization.
- Add unit test for warmup logic.

This moves the ONNX Runtime initialization cost (buffer allocation, graph optimization) from the first user interaction to application startup, improving perceived responsiveness.

Co-authored-by: Whamp <1115485+Whamp@users.noreply.github.com>
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PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
🟢
No security concerns identified No security vulnerabilities detected by AI analysis. Human verification advised for critical code.
Ticket Compliance
🎫 No ticket provided
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Codebase Duplication Compliance
Codebase context is not defined

Follow the guide to enable codebase context checks.

Custom Compliance
🟢
Generic: Comprehensive Audit Trails

Objective: To create a detailed and reliable record of critical system actions for security analysis
and compliance.

Status: Passed

Learn more about managing compliance generic rules or creating your own custom rules

Generic: Meaningful Naming and Self-Documenting Code

Objective: Ensure all identifiers clearly express their purpose and intent, making code
self-documenting

Status: Passed

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Generic: Secure Error Handling

Objective: To prevent the leakage of sensitive system information through error messages while
providing sufficient detail for internal debugging.

Status: Passed

Learn more about managing compliance generic rules or creating your own custom rules

Generic: Secure Logging Practices

Objective: To ensure logs are useful for debugging and auditing without exposing sensitive
information like PII, PHI, or cardholder data.

Status: Passed

Learn more about managing compliance generic rules or creating your own custom rules

Generic: Security-First Input Validation and Data Handling

Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent
vulnerabilities

Status: Passed

Learn more about managing compliance generic rules or creating your own custom rules

Generic: Robust Error Handling and Edge Case Management

Objective: Ensure comprehensive error handling that provides meaningful context and graceful
degradation

Status:
Broad exception catch: warmup() catches Exception and only logs a generic warning without additional operational
context (e.g., model/provider) or stack trace, which may hinder diagnosis if warmup
failures correlate with later inference errors.

Referred Code
def warmup(self) -> None:
    """Performs a dummy inference to initialize ONNX buffers."""
    self._logger.debug("Warming up Parakeet model...")
    dummy_audio = np.zeros(16_000, dtype=np.float32)
    try:
        self.transcribe(dummy_audio)
    except Exception as exc:
        self._logger.warning("Warmup failed: %s", exc)

Learn more about managing compliance generic rules or creating your own custom rules

Compliance status legend 🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

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PR Code Suggestions ✨

Explore these optional code suggestions:

CategorySuggestion                                                                                                                                    Impact
Possible issue
Fix race condition during transcription

Fix a race condition in the transcribe method by extending the lock to cover the
entire operation, preventing the model from being unloaded while in use.

src/chirp/parakeet_manager.py [135-145]

 def transcribe(self, audio: np.ndarray, *, sample_rate: int = 16_000, language: Optional[str] = None) -> str:
     with self._lock:
         self._last_access = time.time()
-    model = self.ensure_loaded()
-    if audio.ndim > 1:
-        audio = audio.reshape(-1)
-    waveform = audio.astype(np.float32, copy=False)
-    if waveform.size == 0:
-        return ""
-    result = model.recognize(waveform, sample_rate=sample_rate, language=language)
-    return result if isinstance(result, str) else str(result)
+        model = self.ensure_loaded()
+        if audio.ndim > 1:
+            audio = audio.reshape(-1)
+        waveform = audio.astype(np.float32, copy=False)
+        if waveform.size == 0:
+            return ""
+        result = model.recognize(waveform, sample_rate=sample_rate, language=language)
+        return result if isinstance(result, str) else str(result)

[To ensure code accuracy, apply this suggestion manually]

Suggestion importance[1-10]: 9

__

Why: The suggestion correctly identifies a critical race condition in the transcribe method where the model could be unloaded by the monitor thread after the lock is released, potentially causing a crash during inference.

High
Let model load errors surface

Refactor the warmup method to ensure model loading errors are not caught,
allowing them to propagate and cause a startup failure, while still handling
potential inference errors.

src/chirp/parakeet_manager.py [81-88]

 def warmup(self) -> None:
     """Performs a dummy inference to initialize ONNX buffers."""
     self._logger.debug("Warming up Parakeet model...")
+    # Load the model and let load errors propagate
+    model = self.ensure_loaded()
+    # Prepare dummy input
     dummy_audio = np.zeros(16_000, dtype=np.float32)
     try:
-        self.transcribe(dummy_audio)
+        model.recognize(dummy_audio, sample_rate=16_000)
     except Exception as exc:
-        self._logger.warning("Warmup failed: %s", exc)
+        self._logger.warning("Warmup inference failed: %s", exc)
  • Apply / Chat
Suggestion importance[1-10]: 7

__

Why: The suggestion correctly points out that warmup could silently ignore model loading errors. Separating model loading from inference makes error handling more robust and prevents the application from starting in a broken state.

Medium
  • More

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