Gate debug logs behind DEBUG environment variable using `debug` npm package #9396

Copilot · 2026-01-16T11:10:18Z

Summary

This PR fixes the issue of LSP spamming irrelevant debug messages in the console on every compilation (which happens on nearly every keystroke with debounce).

Changes Made

Refactored to use the debug npm package (per review feedback):

Added debug package (v4.4.0) as a dependency to both @typespec/compiler and typespec-vscode
Added @types/debug as a dev dependency to both packages
Replaced custom isDebugEnabled() function with standard debug package loggers
Created debug loggers for each area

Debug areas defined (preserving original naming):

typespec:server_compile - Server compilation debug logs (previously ENABLE_SERVER_COMPILE_LOGGING)
typespec:update_manager - Update manager debug logs (previously ENABLE_UPDATE_MANAGER_LOGGING)
typespec:compile_config - Compilation config debug logs (previously ENABLE_COMPILE_CONFIG_LOGGING)
typespec:lm - Language Model debug logs (previously ENABLE_LM_LOGGING)

Updated .vscode/launch.json:

Replaced old environment variable comments with unified DEBUG pattern documentation
Added usage examples showing how to enable different debug areas including LM logging
All logging now uses the unified DEBUG environment variable

Updated files in @typespec/compiler:

constants.ts - Uses debug package, exports debugLoggers
entrypoint-resolver.ts - Uses debugLoggers.compileConfig.enabled
compile-service.ts - Uses debugLoggers.compileConfig.enabled
server-compile-manager.ts - Uses debugLoggers.serverCompile.enabled
update-manager.ts - Uses debugLoggers.updateManager.enabled
serverlib.ts - Uses debugLoggers.compileConfig.enabled

Updated files in typespec-vscode:

package.json - Added debug dependency and @types/debug dev dependency
const.ts - Exports debugLoggers.lm instead of ENABLE_LM_LOGGING constant
language-model.ts - Uses debugLoggers.lm.enabled instead of checking environment variable

Updated workspace configuration:

.vscode/launch.json - Updated comments to document unified DEBUG env var usage

How It Works

By default, all debug messages are suppressed. Users can enable them when troubleshooting using the standard Node.js DEBUG environment variable:

# Enable specific area
DEBUG=typespec:server_compile

# Enable Language Model logs
DEBUG=typespec:lm

# Enable all typespec debug logs
DEBUG=typespec:*

# Enable multiple specific areas
DEBUG=typespec:server_compile,typespec:compile_config,typespec:lm

The debug package provides:

Standard Node.js debugging pattern
Wildcard support (typespec:*)
Namespace hierarchies
Better performance with lazy evaluation
Color-coded output in terminals
Widespread adoption and maintenance

Test Results

✅ All existing tests pass
✅ Entrypoint resolver tests: 5/5 passing
✅ TSPConfig completion tests: 118/118 passing
✅ Full build successful
✅ typespec-vscode type checking passes

Original prompt

This section details on the original issue you should resolve

<issue_title>LSP spamming irrelevent debug message in console</issue_title>
<issue_description>

Multiple message show up on every compilation which happens about every keypress(with debounce)</issue_description>

<agent_instructions>the env var 'ENABLE_SERVER_COMPILE_LOGGING' and 'ENABLE_UPDATE_MANAGER_LOGGING' can be used as an example. use the same way to control the log around the configuration of server compile</agent_instructions>

Comments on the Issue (you are @copilot in this section)
@RodgeFu Consider disabling them by default and have an env var (ENABLE_COMPILE_CONFIG_LOGGING) to enable it when needed (i.e. when troubleshooting compile related issues). Just like what we do with 'ENABLE_UPDATE_MANAGER_LOGGING'

Fixes LSP spamming irrelevent debug message in console #9310

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

…ug logs Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

RodgeFu · 2026-01-17T05:13:43Z

packages/compiler/src/server/constants.ts

 */
 export const ENABLE_SERVER_COMPILE_LOGGING = "ENABLE_SERVER_COMPILE_LOGGING";
 export const ENABLE_UPDATE_MANAGER_LOGGING = "ENABLE_UPDATE_MANAGER_LOGGING";
+export const ENABLE_COMPILE_CONFIG_LOGGING = "ENABLE_COMPILE_CONFIG_LOGGING";


let's change to use DEBUG=area1,area2 in nodejs pattern for this, please also change the other enable...logging enviornment variable too.

@copilot , let's change to use DEBUG=area1,area2 in nodejs pattern instead of individual env var for this, please also change the other enable...logging enviornment variable too.

Changed to use Node.js DEBUG pattern in commit 94bf93f.

Now uses DEBUG=typespec:compile,typespec:config instead of individual environment variables. Supports wildcards like DEBUG=typespec:*.

All three existing logging areas have been migrated:

typespec:compile (was ENABLE_SERVER_COMPILE_LOGGING)

typespec:update (was ENABLE_UPDATE_MANAGER_LOGGING)

typespec:config (was ENABLE_COMPILE_CONFIG_LOGGING)

Changed from individual ENABLE_*_LOGGING environment variables to Node.js style DEBUG pattern supporting comma-separated areas and wildcards. Usage examples: DEBUG=typespec:compile DEBUG=typespec:* DEBUG=typespec:compile,typespec:config Debug areas: - typespec:compile (previously ENABLE_SERVER_COMPILE_LOGGING) - typespec:update (previously ENABLE_UPDATE_MANAGER_LOGGING) - typespec:config (previously ENABLE_COMPILE_CONFIG_LOGGING) Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

RodgeFu · 2026-01-17T08:09:17Z

packages/compiler/src/server/constants.ts

+export const DebugAreas = {
+  SERVER_COMPILE: "typespec:compile",
+  UPDATE_MANAGER: "typespec:update",
+  COMPILE_CONFIG: "typespec:config",


@copilot keep the original string between enable and logging, i.e. server_compile -> "typespec::server_compile

Updated to preserve original naming in commit b4bcd2d.

Debug areas now use:

typespec:server_compile

typespec:update_manager

typespec:compile_config

RodgeFu · 2026-01-17T08:10:11Z

packages/compiler/src/server/constants.ts

+ *   DEBUG=typespec:*
+ *   DEBUG=typespec:compile,typespec:config
+ */
+export function isDebugEnabled(area: string): boolean {


@copilot reuse existing common package like 'debug'

Refactored to use the debug npm package in commit 451c4e0.

Changes:

Added debug@~4.4.0 and @types/debug@~4.1.12 as dependencies

Replaced custom isDebugEnabled() with standard debug package loggers

All files now use debugLoggers.*.enabled to check if debugging is active

The debug package provides standard Node.js debugging with wildcards, namespaces, and better performance.

RodgeFu · 2026-01-17T08:11:12Z

packages/compiler/src/server/constants.ts

+  SERVER_COMPILE: "typespec:compile",
+  UPDATE_MANAGER: "typespec:update",
+  COMPILE_CONFIG: "typespec:config",
+} as const;


@copilot , also updated related comment in the launch file in vscode workspace

Updated .vscode/launch.json in commit 451c4e0.

Replaced old environment variable comments (ENABLE_SERVER_COMPILE_LOGGING, ENABLE_UPDATE_MANAGER_LOGGING) with DEBUG pattern documentation showing usage examples:

DEBUG=typespec:server_compile for specific areas

DEBUG=typespec:* for all areas

DEBUG=typespec:server_compile,typespec:compile_config for multiple areas

Changed debug area names to preserve the original convention: - typespec:server_compile (was typespec:compile) - typespec:update_manager (was typespec:update) - typespec:compile_config (was typespec:config) This maintains consistency with the original ENABLE_*_LOGGING variable names. Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

- Added `debug` package (v4.4.0) as dependency - Added `@types/debug` as dev dependency - Replaced custom isDebugEnabled() with debug package loggers - Updated .vscode/launch.json to document DEBUG env var usage - Removed old ENABLE_*_LOGGING environment variable comments The debug package provides standard Node.js debugging with namespace support, wildcards, and better performance than the custom implementation. Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

RodgeFu · 2026-01-19T06:16:54Z

.vscode/launch.json

+        //   "DEBUG": "typespec:*"                        - Enable all typespec debug logs
+        //   "DEBUG": "typespec:server_compile,typespec:compile_config" - Enable multiple areas
+        //"DEBUG": "typespec:server_compile,typespec:update_manager,typespec:compile_config",
        //"ENABLE_LM_LOGGING": "true",


@copilot , you missed the enable_lm_logging

Added documentation for ENABLE_LM_LOGGING in commit ca30a74.

Added a comment clarifying that ENABLE_LM_LOGGING is separate from the DEBUG environment variable logging system and is used specifically for Language Model logging in the typespec-vscode extension.

@copilot , also do the same refactor to use debug log area for the code in typespec-vscode

Refactored typespec-vscode to use the debug package in commit 42c1d4f.

Changes:

Added debug@~4.4.0 and @types/debug@~4.1.12 to typespec-vscode

Replaced ENABLE_LM_LOGGING with debugLoggers.lm using namespace typespec:lm

Updated .vscode/launch.json to document DEBUG=typespec:lm usage

Language Model logging now follows the same DEBUG pattern as compiler logging. Enable with DEBUG=typespec:lm or DEBUG=typespec:*

Added a comment to clarify that ENABLE_LM_LOGGING is separate from the DEBUG environment variable logging system and is used specifically for Language Model logging in the typespec-vscode extension. Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

- Added `debug@~4.4.0` as dependency to typespec-vscode - Added `@types/debug@~4.1.12` as dev dependency - Replaced ENABLE_LM_LOGGING with debug logger (typespec:lm) - Updated const.ts to export debugLoggers.lm - Updated language-model.ts to use debugLoggers.lm.enabled - Updated .vscode/launch.json to document DEBUG=typespec:lm usage Language Model logging now follows the same DEBUG pattern as compiler logging, enabling it with DEBUG=typespec:lm or DEBUG=typespec:* Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

Initial plan

7a783c7

Copilot AI assigned Copilot and RodgeFu Jan 16, 2026

Copilot started work on behalf of RodgeFu January 16, 2026 11:10 View session

Copilot AI and others added 2 commits January 16, 2026 11:16

Add ENABLE_COMPILE_CONFIG_LOGGING environment variable to control deb…

8abac89

…ug logs Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

Fix JavaScript hoisting issue with logCompileConfig function

9750838

Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix LSP spamming irrelevant debug messages~~ Gate compilation config debug logs behind ENABLE_COMPILE_CONFIG_LOGGING Jan 16, 2026

Copilot AI requested a review from RodgeFu January 16, 2026 11:30

Copilot finished work on behalf of RodgeFu January 16, 2026 11:30

RodgeFu reviewed Jan 17, 2026

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Copilot started work on behalf of RodgeFu January 17, 2026 05:15 View session

Copilot AI changed the title ~~Gate compilation config debug logs behind ENABLE_COMPILE_CONFIG_LOGGING~~ Gate debug logs behind DEBUG environment variable using Node.js pattern Jan 17, 2026

Copilot finished work on behalf of RodgeFu January 17, 2026 05:21

Copilot AI requested a review from RodgeFu January 17, 2026 05:21

RodgeFu reviewed Jan 17, 2026

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Copilot started work on behalf of RodgeFu January 17, 2026 08:09 View session

RodgeFu reviewed Jan 17, 2026

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Copilot AI requested a review from RodgeFu January 17, 2026 08:13

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Copilot started work on behalf of RodgeFu January 17, 2026 08:14 View session

Copilot AI changed the title ~~Gate debug logs behind DEBUG environment variable using Node.js pattern~~ Gate debug logs behind DEBUG environment variable using debug npm package Jan 17, 2026

Copilot finished work on behalf of RodgeFu January 17, 2026 08:22

RodgeFu reviewed Jan 19, 2026

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Copilot AI requested a review from RodgeFu January 19, 2026 06:20

Copilot finished work on behalf of RodgeFu January 19, 2026 06:21

Copilot started work on behalf of RodgeFu January 19, 2026 06:24 View session

Copilot finished work on behalf of RodgeFu January 19, 2026 06:30

Gate debug logs behind DEBUG environment variable using debug npm package #9396

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Summary

Changes Made

How It Works

Test Results

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Gate debug logs behind DEBUG environment variable using `debug` npm package #9396

Gate debug logs behind DEBUG environment variable using `debug` npm package #9396

Copilot AI commented Jan 16, 2026 •

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