update supplemental context logic according to science feedback

Author: tomcat323

packages/core/src/codewhisperer/nextEditPrediction/PredictionTracker.ts

@@ -7,7 +7,7 @@ import * as vscode from 'vscode'
 import * as path from 'path'
 import fs from '../../shared/fs/fs'
 import { getLogger } from '../../shared/logger/logger'
-import * as diffGenerator from './diffGenerator'
+import * as diffGenerator from './diffContextGenerator'
 import * as codewhispererClient from '../client/codewhisperer'
 
 export interface FileTrackerConfig {

packages/core/src/codewhisperer/nextEditPrediction/diffGenerator.ts renamed to packages/core/src/codewhisperer/nextEditPrediction/diffContextGenerator.ts

@@ -19,7 +19,7 @@ import * as codewhispererClient from '../client/codewhisperer'
  * @param contextSize - Number of context lines to include (default: 3)
  * @returns Unified diff as a string
  */
-export async function generateUnifiedDiffWithTimestamps(
+async function generateUnifiedDiffWithTimestamps(
     oldFilePath: string,
     newFilePath: string,
     oldContent: string,
@@ -33,8 +33,8 @@ export async function generateUnifiedDiffWithTimestamps(
         newFilePath,
         oldContent,
         newContent,
-        `${oldTimestamp}`, // Old file label with timestamp
-        `${newTimestamp}`, // New file label with timestamp
+        String(oldTimestamp),
+        String(newTimestamp),
         { context: contextSize }
     )
 
@@ -64,7 +64,10 @@ export interface SnapshotContent {
  * @param currentContent - Current content of the file
  * @param snapshotContents - List of snapshot contents sorted by timestamp (oldest first)
  * @param maxContexts - Maximum number of supplemental contexts to return
- * @returns Array of SupplementalContext objects
+ * @returns Array of SupplementalContext objects, T_0 being the snapshot of current file content:
+ *  U0: udiff of T_0 and T_1
+ *  U1: udiff of T_0 and T_2
+ *  U2: udiff of T_0 and T_3
  */
 export async function generateDiffContexts(
     filePath: string,
@@ -79,38 +82,28 @@ export async function generateDiffContexts(
     const supplementalContexts: codewhispererClient.SupplementalContext[] = []
     const currentTimestamp = Date.now()
 
-    // Treat current content as the last snapshot
-    const allContents = [
-        ...snapshotContents,
-        {
-            filePath,
-            content: currentContent,
-            timestamp: currentTimestamp,
-        },
-    ]
-
-    // Generate diffs between all adjacent snapshots (including current content)
-    for (let i = 0; i < allContents.length - 1; i++) {
-        const oldSnapshot = allContents[i]
-        const newSnapshot = allContents[i + 1]
+    // Create a copy of snapshots and reverse it so newest snapshots are processed first
+    const sortedSnapshots = [...snapshotContents].reverse()
 
+    // Generate diffs between each snapshot and the current content
+    for (const snapshot of sortedSnapshots) {
         try {
-            const diff = await generateUnifiedDiffWithTimestamps(
-                oldSnapshot.filePath,
-                newSnapshot.filePath,
-                oldSnapshot.content,
-                newSnapshot.content,
-                oldSnapshot.timestamp,
-                newSnapshot.timestamp
+            const unifiedDiff = await generateUnifiedDiffWithTimestamps(
+                snapshot.filePath,
+                filePath,
+                snapshot.content,
+                currentContent,
+                snapshot.timestamp,
+                currentTimestamp
             )
 
             supplementalContexts.push({
-                filePath: oldSnapshot.filePath,
-                content: diff,
+                filePath: snapshot.filePath,
+                content: unifiedDiff,
                 type: 'PreviousEditorState',
                 metadata: {
                     previousEditorStateMetadata: {
-                        timeOffset: currentTimestamp - oldSnapshot.timestamp,
+                        timeOffset: currentTimestamp - snapshot.timestamp,
                     },
                 },
             })
@@ -121,7 +114,7 @@ export async function generateDiffContexts(
 
     // Limit the number of supplemental contexts based on config
     if (supplementalContexts.length > maxContexts) {
-        return supplementalContexts.slice(-maxContexts)
+        return supplementalContexts.slice(0, maxContexts)
     }
 
     return supplementalContexts