fix: autocomplete performance issues #8364

RomneyDa · 2025-10-21T07:54:09Z

Description

TODO Make sure to revert changes from #8391

[ What changed? Feel free to be brief. ]

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[] The relevant docs, if any, have been updated or created
[] The relevant tests, if any, have been updated or created

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Tests

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Summary by cubic

Cut down expensive file reads in autocomplete by building prefix/suffix from already-loaded lines, deferring snippet reads, and pruning by tokens on line arrays. Removes IDE.onDidChangeActiveTextEditor to simplify event handling and avoid unnecessary work.

Refactors
- constructInitialPrefixSuffix now takes file lines and returns prefix/suffix lines; avoids extra readFile calls.
- HelperVars uses new pruneFromTop/pruneFromBottom (line-based) to compute prefix/suffix within token budgets.
- getRangeInString returns string[]; call sites updated to work on lines and join only at the end.
- RecentlyVisitedRangesService caches line positions and reads file content only when serving snippets; getSnippets is async and completion provider awaits it.
- Consolidated file reads across retrieval, indexing, LSP, and utilities; added lightweight instrumentation to track when files are read.
Migration
- Removed IDE.onDidChangeActiveTextEditor. Extensions should subscribe to VS Code’s onDidChangeActiveTextEditor and forward files/opened events.
- Update callers of constructInitialPrefixSuffix to pass pre-split lines and handle string[] outputs; adjust any usage of getRangeInString to expect string[].

cubic-dev-ai

4 issues found across 29 files

Prompt for AI agents (all 4 issues)


Understand the root cause of the following 4 issues and fix them.


<file name="extensions/vscode/src/extension/VsCodeExtension.ts">

<violation number="1" location="extensions/vscode/src/extension/VsCodeExtension.ts:638">
Register the `onDidChangeActiveTextEditor` listener with the extension context so it is disposed during deactivation to avoid leaking the handler.</violation>
</file>

<file name="core/autocomplete/snippets/getAllSnippets.ts">

<violation number="1" location="core/autocomplete/snippets/getAllSnippets.ts:131">
This debug console.log runs on every file read from the recently opened cache, so autocomplete will emit a log per file on each invocation; this adds synchronous logging overhead and floods the console, undermining the performance improvements you&#39;re targeting. Please drop or gate the log before merging.</violation>
</file>

<file name="core/autocomplete/util/HelperVars.ts">

<violation number="1" location="core/autocomplete/util/HelperVars.ts:150">
fullSuffixLines should return the cached array; pointing to fullSuffixLines causes infinite recursion at runtime.</violation>
</file>

<file name="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts">

<violation number="1" location="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts:64">
Map#get returns undefined for unknown keys, so this guard never runs and the file security check is skipped, letting flagged files through.</violation>
</file>

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cubic-dev-ai · 2025-10-21T08:44:47Z

extensions/vscode/src/extension/VsCodeExtension.ts


-    this.ide.onDidChangeActiveTextEditor((filepath) => {
-      void this.core.invoke("files/opened", { uris: [filepath] });
+    vscode.window.onDidChangeActiveTextEditor((editor) => {


Register the onDidChangeActiveTextEditor listener with the extension context so it is disposed during deactivation to avoid leaking the handler.

Prompt for AI agents

Address the following comment on extensions/vscode/src/extension/VsCodeExtension.ts at line 638: <comment>Register the `onDidChangeActiveTextEditor` listener with the extension context so it is disposed during deactivation to avoid leaking the handler.</comment> <file context> @@ -634,8 +635,12 @@ export class VsCodeExtension { - this.ide.onDidChangeActiveTextEditor((filepath) => { - void this.core.invoke("files/opened", { uris: [filepath] }); + vscode.window.onDidChangeActiveTextEditor((editor) => { + if (editor) { + this.core.invoke("files/opened", { </file context>

cubic-dev-ai · 2025-10-21T08:44:47Z

core/autocomplete/snippets/getAllSnippets.ts

      // Create a promise that resolves to a snippet or null
      const readPromise = new Promise<AutocompleteCodeSnippet | null>(
        (resolve) => {
+          console.log(


This debug console.log runs on every file read from the recently opened cache, so autocomplete will emit a log per file on each invocation; this adds synchronous logging overhead and floods the console, undermining the performance improvements you're targeting. Please drop or gate the log before merging.

Prompt for AI agents

Address the following comment on core/autocomplete/snippets/getAllSnippets.ts at line 131: <comment>This debug console.log runs on every file read from the recently opened cache, so autocomplete will emit a log per file on each invocation; this adds synchronous logging overhead and floods the console, undermining the performance improvements you're targeting. Please drop or gate the log before merging.</comment> <file context> @@ -128,6 +128,9 @@ const getSnippetsFromRecentlyOpenedFiles = async ( // Create a promise that resolves to a snippet or null const readPromise = new Promise<AutocompleteCodeSnippet | null>( (resolve) => { + console.log( + `read file - getAllSnippets getSnippetsFromRecentlyOpenedFiles - ${fileUri}`, + ); </file context>

core/autocomplete/util/HelperVars.ts

cubic-dev-ai · 2025-10-21T08:44:48Z

extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts

+    let securityCheck = this.securityChecks.get(
+      event.textEditor.document.fileName,
+    );
+    if (securityCheck === null) {


Map#get returns undefined for unknown keys, so this guard never runs and the file security check is skipped, letting flagged files through.

Prompt for AI agents

Address the following comment on extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts at line 64: <comment>Map#get returns undefined for unknown keys, so this guard never runs and the file security check is skipped, letting flagged files through.</comment> <file context> @@ -39,95 +42,120 @@ export class RecentlyVisitedRangesService { + let securityCheck = this.securityChecks.get( + event.textEditor.document.fileName, + ); + if (securityCheck === null) { + securityCheck = isSecurityConcern(event.textEditor.document.fileName); + this.securityChecks.set( </file context>

Suggested change

if (securityCheck === null) {

if (securityCheck === undefined) {

cubic-dev-ai

4 issues found across 35 files

Prompt for AI agents (all 4 issues)


Understand the root cause of the following 4 issues and fix them.


<file name="extensions/vscode/src/extension/VsCodeExtension.ts">

<violation number="1" location="extensions/vscode/src/extension/VsCodeExtension.ts:637">
Ensure the Disposable returned by onDidChangeActiveTextEditor is registered in context.subscriptions so the listener is cleaned up on deactivate.</violation>
</file>

<file name="core/tools/implementations/readFileRange.integration.vitest.ts">

<violation number="1" location="core/tools/implementations/readFileRange.integration.vitest.ts:200">
`readFileRangeImpl` still obtains file ranges via `readRangeInFile`, which calls `ide.readFile(uri)` without range options. This assertion will always fail because no second argument is ever passed to `readFile`, breaking the test.</violation>
</file>

<file name="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts">

<violation number="1" location="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts:46">
The feature-flag branch now always runs, so when the flag returns undefined numSurroundingLines becomes undefined, producing NaN slice bounds and empty snippets for most users.</violation>

<violation number="2" location="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts:65">
securityChecks never caches results because Map.get returns undefined, so the isSecurityConcern guard is skipped and sensitive files are now stored.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

cubic-dev-ai · 2025-10-21T09:52:11Z

extensions/vscode/src/extension/VsCodeExtension.ts


-    this.ide.onDidChangeActiveTextEditor((filepath) => {
-      void this.core.invoke("files/opened", { uris: [filepath] });
+    vscode.window.onDidChangeActiveTextEditor((editor) => {


Ensure the Disposable returned by onDidChangeActiveTextEditor is registered in context.subscriptions so the listener is cleaned up on deactivate.

Prompt for AI agents

Address the following comment on extensions/vscode/src/extension/VsCodeExtension.ts at line 637: <comment>Ensure the Disposable returned by onDidChangeActiveTextEditor is registered in context.subscriptions so the listener is cleaned up on deactivate.</comment> <file context> @@ -634,8 +634,12 @@ export class VsCodeExtension { - this.ide.onDidChangeActiveTextEditor((filepath) => { - void this.core.invoke("files/opened", { uris: [filepath] }); + vscode.window.onDidChangeActiveTextEditor((editor) => { + if (editor) { + this.core.invoke("files/opened", { </file context>

cubic-dev-ai · 2025-10-21T09:52:11Z

core/tools/implementations/readFileRange.integration.vitest.ts


  // Verify correct 0-based conversion
-  expect(mockIde.readRangeInFile).toHaveBeenCalledWith("file:///test.txt", {
+  expect(mockIde.readFile).toHaveBeenCalledWith("file:///test.txt", {


readFileRangeImpl still obtains file ranges via readRangeInFile, which calls ide.readFile(uri) without range options. This assertion will always fail because no second argument is ever passed to readFile, breaking the test.

Prompt for AI agents

Address the following comment on core/tools/implementations/readFileRange.integration.vitest.ts at line 200: <comment>`readFileRangeImpl` still obtains file ranges via `readRangeInFile`, which calls `ide.readFile(uri)` without range options. This assertion will always fail because no second argument is ever passed to `readFile`, breaking the test.</comment> <file context> @@ -197,7 +197,7 @@ test("readFileRangeImpl handles normal ranges correctly", async () => { // Verify correct 0-based conversion - expect(mockIde.readRangeInFile).toHaveBeenCalledWith("file:///test.txt", { + expect(mockIde.readFile).toHaveBeenCalledWith("file:///test.txt", { start: { line: 1, character: 0 }, // 2 - 1 end: { line: 3, character: Number.MAX_SAFE_INTEGER }, // 4 - 1 </file context>

cubic-dev-ai · 2025-10-21T09:52:12Z

extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts

+    let securityCheck = this.securityChecks.get(
+      event.textEditor.document.fileName,
+    );
+    if (securityCheck === null) {


securityChecks never caches results because Map.get returns undefined, so the isSecurityConcern guard is skipped and sensitive files are now stored.

Prompt for AI agents

Address the following comment on extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts at line 65: <comment>securityChecks never caches results because Map.get returns undefined, so the isSecurityConcern guard is skipped and sensitive files are now stored.</comment> <file context> @@ -39,95 +43,120 @@ export class RecentlyVisitedRangesService { + let securityCheck = this.securityChecks.get( + event.textEditor.document.fileName, + ); + if (securityCheck === null) { + securityCheck = isSecurityConcern(event.textEditor.document.fileName); + this.securityChecks.set( </file context>

Suggested change

if (securityCheck === null) {

if (securityCheck === undefined) {

cubic-dev-ai · 2025-10-21T09:52:12Z

extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts

      );

-    if (recentlyVisitedRangesNumSurroundingLines) {
+    if (true) {


The feature-flag branch now always runs, so when the flag returns undefined numSurroundingLines becomes undefined, producing NaN slice bounds and empty snippets for most users.

Prompt for AI agents

Address the following comment on extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts at line 46: <comment>The feature-flag branch now always runs, so when the flag returns undefined numSurroundingLines becomes undefined, producing NaN slice bounds and empty snippets for most users.</comment> <file context> @@ -39,95 +43,120 @@ export class RecentlyVisitedRangesService { ); - if (recentlyVisitedRangesNumSurroundingLines) { + if (true) { this.isEnabled = true; this.numSurroundingLines = recentlyVisitedRangesNumSurroundingLines; </file context>

Suggested change

if (true) {

if (recentlyVisitedRangesNumSurroundingLines != null) {

cubic-dev-ai

5 issues found across 35 files

Prompt for AI agents (all 5 issues)


Understand the root cause of the following 5 issues and fix them.


<file name="core/tools/implementations/readFileRange.ts">

<violation number="1" location="core/tools/implementations/readFileRange.ts:49">
Switching to the shared readRangeInFile helper causes readFileRange to prepend a newline for single-line ranges; for startLine === endLine the helper returns &quot;\n&lt;line&gt;&quot; instead of just the requested line, which is a functional regression for this tool.</violation>
</file>

<file name="core/autocomplete/context/ImportDefinitionsService.ts">

<violation number="1" location="core/autocomplete/context/ImportDefinitionsService.ts:26">
Commenting out the onDidChangeActiveTextEditor handler stops warming this cache when the user switches files, so import definition lookups now return undefined instead of the cached definitions.</violation>
</file>

<file name="core/autocomplete/snippets/getAllSnippets.ts">

<violation number="1" location="core/autocomplete/snippets/getAllSnippets.ts:131">
This new console.log will fire for every recently opened file read, spamming the console and adding overhead in production usages. Please remove it or gate it behind the existing logging/instrumentation mechanism.</violation>
</file>

<file name="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts">

<violation number="1" location="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts:46">
Restore the feature-flag guard before enabling recently visited ranges so numSurroundingLines isn&#39;t set to undefined when the flag is missing.</violation>

<violation number="2" location="extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts:65">
Ensure the security check cache initializes when the lookup returns undefined so isSecurityConcern runs at least once per file.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

cubic-dev-ai · 2025-10-21T09:58:15Z

core/tools/implementations/readFileRange.ts

-  // Use the IDE's readRangeInFile method with 0-based range (IDE expects 0-based internally)
-  const content = await extras.ide.readRangeInFile(resolvedPath.uri, {
+  // readRangeInFile expects 0-based range indexes
+  const content = await readRangeInFile(extras.ide, resolvedPath.uri, {


Switching to the shared readRangeInFile helper causes readFileRange to prepend a newline for single-line ranges; for startLine === endLine the helper returns "\n" instead of just the requested line, which is a functional regression for this tool.

Prompt for AI agents

Address the following comment on core/tools/implementations/readFileRange.ts at line 49: <comment>Switching to the shared readRangeInFile helper causes readFileRange to prepend a newline for single-line ranges; for startLine === endLine the helper returns "\n<line>" instead of just the requested line, which is a functional regression for this tool.</comment> <file context> @@ -44,8 +45,8 @@ export const readFileRangeImpl: ToolImpl = async (args, extras) => { - // Use the IDE's readRangeInFile method with 0-based range (IDE expects 0-based internally) - const content = await extras.ide.readRangeInFile(resolvedPath.uri, { + // readRangeInFile expects 0-based range indexes + const content = await readRangeInFile(extras.ide, resolvedPath.uri, { start: { line: startLine - 1, // Convert from 1-based to 0-based </file context>

cubic-dev-ai · 2025-10-21T09:58:15Z

core/autocomplete/context/ImportDefinitionsService.ts

-        );
-    });
+    console.log("new import definitions service");
+    //  ide.onDidChangeActiveTextEditor((filepath) => {


Commenting out the onDidChangeActiveTextEditor handler stops warming this cache when the user switches files, so import definition lookups now return undefined instead of the cached definitions.

Prompt for AI agents

Address the following comment on core/autocomplete/context/ImportDefinitionsService.ts at line 26: <comment>Commenting out the onDidChangeActiveTextEditor handler stops warming this cache when the user switches files, so import definition lookups now return undefined instead of the cached definitions.</comment> <file context> @@ -21,15 +22,16 @@ export class ImportDefinitionsService { - ); - }); + console.log("new import definitions service"); + // ide.onDidChangeActiveTextEditor((filepath) => { + // this.cache + // .initKey(filepath) </file context>

cubic-dev-ai · 2025-10-21T09:58:15Z

core/autocomplete/snippets/getAllSnippets.ts

      // Create a promise that resolves to a snippet or null
      const readPromise = new Promise<AutocompleteCodeSnippet | null>(
        (resolve) => {
+          console.log(


This new console.log will fire for every recently opened file read, spamming the console and adding overhead in production usages. Please remove it or gate it behind the existing logging/instrumentation mechanism.

Prompt for AI agents

Address the following comment on core/autocomplete/snippets/getAllSnippets.ts at line 131: <comment>This new console.log will fire for every recently opened file read, spamming the console and adding overhead in production usages. Please remove it or gate it behind the existing logging/instrumentation mechanism.</comment> <file context> @@ -128,6 +128,9 @@ const getSnippetsFromRecentlyOpenedFiles = async ( // Create a promise that resolves to a snippet or null const readPromise = new Promise<AutocompleteCodeSnippet | null>( (resolve) => { + console.log( + `read file - getAllSnippets getSnippetsFromRecentlyOpenedFiles - ${fileUri}`, + ); </file context>

cubic-dev-ai · 2025-10-21T09:58:15Z

extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts

+    let securityCheck = this.securityChecks.get(
+      event.textEditor.document.fileName,
+    );
+    if (securityCheck === null) {


Ensure the security check cache initializes when the lookup returns undefined so isSecurityConcern runs at least once per file.

Prompt for AI agents

Address the following comment on extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts at line 65: <comment>Ensure the security check cache initializes when the lookup returns undefined so isSecurityConcern runs at least once per file.</comment> <file context> @@ -39,95 +43,120 @@ export class RecentlyVisitedRangesService { + let securityCheck = this.securityChecks.get( + event.textEditor.document.fileName, + ); + if (securityCheck === null) { + securityCheck = isSecurityConcern(event.textEditor.document.fileName); + this.securityChecks.set( </file context>

Suggested change

if (securityCheck === null) {

if (securityCheck === undefined) {

cubic-dev-ai · 2025-10-21T09:58:15Z

extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts

      );

-    if (recentlyVisitedRangesNumSurroundingLines) {
+    if (true) {


Restore the feature-flag guard before enabling recently visited ranges so numSurroundingLines isn't set to undefined when the flag is missing.

Prompt for AI agents

Address the following comment on extensions/vscode/src/autocomplete/RecentlyVisitedRangesService.ts at line 46: <comment>Restore the feature-flag guard before enabling recently visited ranges so numSurroundingLines isn't set to undefined when the flag is missing.</comment> <file context> @@ -39,95 +43,120 @@ export class RecentlyVisitedRangesService { ); - if (recentlyVisitedRangesNumSurroundingLines) { + if (true) { this.isEnabled = true; this.numSurroundingLines = recentlyVisitedRangesNumSurroundingLines; </file context>

RomneyDa added 2 commits October 20, 2025 23:53

fix: autocomplete: reduce expensive operations

ff36b8f

WIP broken - autocomplete performance issues

14caa79

github-project-automation bot added this to Issues and PRs Oct 21, 2025

github-project-automation bot moved this to Todo in Issues and PRs Oct 21, 2025

fix: autocompmlete performance cleanup part 1

d39e7af

cubic-dev-ai bot reviewed Oct 21, 2025

View reviewed changes

RomneyDa added 2 commits October 21, 2025 02:20

wip: autocomplete cleanup

8ff2b85

wip: autcomplete cleanup

3dcf050

cubic-dev-ai bot reviewed Oct 21, 2025

View reviewed changes

RomneyDa mentioned this pull request Oct 22, 2025

fix: temporarily disable RecentlyVisited, RecentlyEdited, and DocumentHistoryTracker #8391

Merged

	if (securityCheck === null) {
	if (securityCheck === undefined) {

	if (true) {
	if (recentlyVisitedRangesNumSurroundingLines != null) {

fix: autocomplete performance issues #8364

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fix: autocomplete performance issues #8364

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