shafty023

Nondeterministic greedy decoding for google.gemma-4-26b-a4b on Bedrock's OpenAI-compatible endpoint

Summary

On the Bedrock OpenAI-compatible chat completions endpoint, repeated identical requests to google.gemma-4-26b-a4b at temperature 0 (greedy decoding) do not return byte-identical completions once the output grows past a few hundred tokens, even though a short 24-token completion at the same setting is byte-identical every time. The divergence is structural, not cosmetic: for a JSON entity/relation extraction task the parsed edge count, edge set, and individual relation labels differ between runs on the same input. This matches an open vLLM issue reporting the same fingerprint on the same checkpoint under CUDA graph replay on specific GPU hardware, which suggests the nondeterminism may originate in the serving stack rather than in any client-side parameter handling.

Environment

• Endpoint: https://bedrock-mantle.us-east-1.api.aws/openai/v1/chat/completions
• Model id: `google.gemma-4-26b-a

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#!/bin/bash

# Hook: UserPromptSubmit
# Purpose: ENFORCE skill checking before starting work

# Return JSON with proper hookSpecificOutput structure per Claude Code docs
cat <<'EOF'
{
  "decision": undefined ,
  "reason": "n/a",

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@Singleton
class Preferences(context: Context) {
    private val prefs: SharedPreferences = context.getSharedPreferences("Prefs", Context.MODE_PRIVATE)

    companion object {
        const val PREF_CURRENT_STATE = "CurrentState"
        const val PREF_LAST_KNOWN_ERROR = "LastKnownError"
        const val PREF_LAST_ACTION_PERFORMED = "LastActionPerformed"
    }

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/**
 * Keeps track of current and prior application state.
 *
 * @param dataStore storage
 */
@Singleton
class StateMachine(private val dataStore: DataStore) {
    /**
     * Storage implementation for our state machine.
     *

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/**
 * A factory that can serialize/deserialize json.
 */
object GsonUtils {
    /**
     * Handles deserializing the json string into a [T] instance.
     *
     * @param json the json to deserialize into an instance of [T]
     * @throws JsonSyntaxException if there is a failure deserializing then this exception is thrown
     */

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/**
 * A storage implementation that enforces whole class serialization/deserialization.
 *
 * This enforces organization of data that needs to be persisted rather than having generic classes
 * with lots of unrelated data.
 *
 * @param context the caller's context
 */
@Singleton
class DataStore(context: Context) {

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abstract class EncryptedDatabase : RoomDatabase() {
    companion object {
        fun getInstance(passcode: CharArray, context: Context):
            EncryptedDatabase = buildDatabase(passcode, context)
        
        private fun buildDatabase(
            passcode: CharArray,
            context: Context
        ): EncryptedDatabase {
            // DatabaseKeyMgr is a singleton that all of the above code is wrapped into.

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/**
 * Returns the database key suitable for using with Room.
 *
 * @param passcode the user's passcode
 * @param context the caller's context
 */
fun getCharKey(passcode: CharArray, context: Context): CharArray {
    if (dbCharKey == null) {
        initKey(passcode, context)
    }

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/**
 * Decrypts the [Storable] instance using the [passcode].
 *
 * @pararm passcode the user's passcode
 * @param storable the storable instance previously saved with [saveToPrefs]
 * @return the raw byte key previously generated with [generateRandomKey]
 */
fun getRawByteKey(passcode: CharArray, storable: Storable): ByteArray {
    val aesWrappedKey = Base64.decode(storable.key, Base64.DEFAULT)
    val iv = Base64.decode(storable.iv, Base64.DEFAULT)

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/**
 * Retrieves the [Storable] instance from prefs.
 *
 * @param context the caller's context
 * @return the storable instance
 */
fun getStorable(context: Context): Storable? {
    val prefs = context.getSharedPreferences("database",
        Context.MODE_PRIVATE)
    val serialized = prefs.getString("key", null)