Gate debug logs behind TYPESPEC_DEBUG environment variable with custom implementation #9396

Copilot · 2026-01-16T11:10:18Z

Plan to fix LSP spamming debug messages

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

Implemented custom debug logging with TYPESPEC_DEBUG environment variable:

Implemented lightweight custom isDebugEnabled() function in dedicated debug.ts files
No external dependencies required (removed debug npm package)
Supports comma-separated debug areas and wildcard patterns
Uses TYPESPEC_DEBUG environment variable (compatible with VSCode)
Added documentation explaining why TYPESPEC_DEBUG is used instead of DEBUG

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 files in @typespec/compiler:

src/server/debug.ts - NEW: Implements custom isDebugEnabled(), exports debugLoggers, documents why TYPESPEC_DEBUG is used
src/server/constants.ts - Removed debug code (now in debug.ts)
src/server/entrypoint-resolver.ts - Imports debugLoggers from debug.ts
src/server/compile-service.ts - Imports debugLoggers from debug.ts
src/server/server-compile-manager.ts - Imports debugLoggers from debug.ts
src/server/update-manager.ts - Imports debugLoggers from debug.ts
src/server/serverlib.ts - Uses regular log function
package.json - No debug package dependency

Updated files in typespec-vscode:

src/debug.ts - NEW: Implements custom isDebugEnabled(), exports debugLoggers.lm, documents why TYPESPEC_DEBUG is used
src/const.ts - Removed debug code (now in debug.ts)
src/lm/language-model.ts - Imports debugLoggers from debug.ts
package.json - No debug package dependency
ThirdPartyNotices.txt - Removed debug package attribution

Updated workspace configuration:

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

Added changelog:

Created changeset documenting the internal change to both packages

Why TYPESPEC_DEBUG Instead of DEBUG?

The standard Node.js DEBUG environment variable is not supported in VSCode extensions due to how VSCode handles environment variables. See VSCode issue #290140 for details. Therefore, we use TYPESPEC_DEBUG as a TypeSpec-specific alternative that works correctly in both the compiler and VSCode extension contexts.

Merge from Main

Successfully merged latest changes from main branch with no conflicts. Updated dependencies and third-party notices accordingly.

How It Works

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

# Enable specific area
TYPESPEC_DEBUG=typespec:server_compile

# Enable Language Model logs
TYPESPEC_DEBUG=typespec:lm

# Enable all typespec debug logs
TYPESPEC_DEBUG=typespec:*

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

The custom implementation provides:

Comma-separated area support
Wildcard support (typespec:*)
Simple pattern matching
No external dependencies
VSCode compatibility
Organized in dedicated debug.ts files
Documented design rationale

Validation

✅ All existing tests pass
✅ Entrypoint resolver tests: 5/5 passing
✅ TSPConfig completion tests: 118/118 passing
✅ Full build successful (all packages)
✅ typespec-vscode type checking passes
✅ No external dependencies added
✅ Debug code properly organized in separate files
✅ Code formatting passes prettier checks
✅ Merged with latest main branch
✅ Changelog added
✅ Design decisions documented
✅ Ready for CI

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>

packages/compiler/src/server/constants.ts

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>

packages/compiler/src/server/constants.ts

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>

.vscode/launch.json

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>

Copilot · 2026-02-05T09:04:18Z

@copilot ,

the last change you made to resolve confliction is incorrect, revert that

the 'DEBUG' env variable is not supported in vscode, let's use 'TYPESPEC_DEBUG' instead and not use 'debug' ...

Changes completed in commit 9757eaf.

Reverted incorrect merge - No merge commit was actually pushed, so working from clean state at 856eeb0
Replaced debug package with custom implementation:
- Removed debug and @types/debug dependencies from both packages
- Implemented simple isDebugEnabled() function with wildcard support
- Changed environment variable from DEBUG to TYPESPEC_DEBUG
- Updated .vscode/launch.json documentation

All tests passing (entrypoint-resolver: 5/5, tspconfig completion: 118/118).

packages/compiler/src/server/constants.ts

- Created packages/compiler/src/server/debug.ts with debug helpers - Created packages/typespec-vscode/src/debug.ts with debug helpers - Removed debug code from constants.ts and const.ts - Updated imports in entrypoint-resolver.ts, compile-service.ts, server-compile-manager.ts, update-manager.ts to use debug.ts - Updated language-model.ts to import from debug.ts This separates debug-related code from constants, improving organization. Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

RodgeFu · 2026-02-06T03:37:27Z

@copilot , merge the change from main branch and make sure pipeline can pass

…-message-issue

Successfully merged latest changes from main branch. Updated ThirdPartyNotices.txt to remove debug package references since we're now using custom implementation without external dependencies. All builds and tests passing after merge. Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

Copilot · 2026-02-06T03:51:34Z

@copilot , merge the change from main branch and make sure pipeline can pass

Merged latest changes from main in commit bae6a68.

Merge successful with no conflicts. Updated ThirdPartyNotices.txt to reflect removal of debug package.

Validation completed:

✅ Full build successful (all packages including website)
✅ All tests passing (entrypoint-resolver: 5/5, tspconfig completion: 118/118)
✅ Code formatting passes prettier checks
✅ Ready for CI

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pkg-pr-new · 2026-02-06T04:59:00Z

Open in StackBlitz

npm i https://pkg.pr.new/microsoft/typespec/@typespec/compiler@9396

npm i https://pkg.pr.new/microsoft/typespec/typespec-vs@9396

npm i https://pkg.pr.new/microsoft/typespec/typespec-vscode@9396

commit: f0f7b6e

RodgeFu · 2026-02-06T05:46:02Z

@copilot , add changelog and add comment to describe why we dont use DEBUG directly (because of microsoft/vscode#290140)

- Added changeset for @typespec/compiler and typespec-vscode - Added comments in both debug.ts files explaining that TYPESPEC_DEBUG is used instead of DEBUG because DEBUG is not supported in VSCode extensions (see microsoft/vscode#290140) This provides context for future maintainers about the design decision. Co-authored-by: RodgeFu <6038235+RodgeFu@users.noreply.github.com>

Copilot · 2026-02-06T05:51:37Z

@copilot , add changelog and add comment to describe why we dont use DEBUG directly (because of microsoft/vscode#290140)

Completed in commit f0f7b6e.

Added changelog: Created changeset using pnpm change add for @typespec/compiler and typespec-vscode packages
Added documentation: Added comments in both debug.ts files explaining that TYPESPEC_DEBUG is used instead of DEBUG because the DEBUG environment variable is not supported in VSCode extensions (see Setting environment variable 'DEBUG' in launch.json doesn't take effect vscode#290140)

The design rationale is now documented for future maintainers.

azure-sdk · 2026-02-06T07:31:06Z

You can try these changes here

🛝 Playground	🌐 Website	🛝 VSCode Extension

timotheeguerin · 2026-02-09T13:21:42Z

packages/compiler/src/server/debug.ts

+ * Note: We use TYPESPEC_DEBUG instead of DEBUG because the DEBUG environment variable
+ * is not supported in VSCode extensions. See: https://github.com/microsoft/vscode/issues/290140
+ *
+ * Usage: TYPESPEC_DEBUG=typespec:server_compile,typespec:compile_config


As it looks like DEBUG will never work with vscode from the issue coment, do you think we still need the typespec: prefix?

Could the area also try to follow the pattern we have for tracing for consitency(Use . instead of _) service.compile service.config

Initial plan

7a783c7

Copilot AI assigned Copilot and RodgeFu Jan 16, 2026

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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

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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

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Gate debug logs behind TYPESPEC_DEBUG environment variable with custom implementation #9396

Gate debug logs behind TYPESPEC_DEBUG environment variable with custom implementation #9396

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Gate debug logs behind TYPESPEC_DEBUG environment variable with custom implementation #9396

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Plan to fix LSP spamming debug messages

Summary

Changes Made

Why TYPESPEC_DEBUG Instead of DEBUG?

Merge from Main

How It Works

Validation

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