[Feature Request]: Integrate PL/pgSQL Debugger (pldebugger) with GUI similar to pgAdmin/DBeaver

Feature Description

Currently, the vscode-pgsql extension is excellent for query execution, schema browsing, and visualization. However, when it comes to debugging stored procedures and functions written in PL/pgSQL, developers have to switch to external tools like pgAdmin or DBeaver.
The current workflow for debugging in VS Code is non-existent. Debugging server-side logic requires a separate, heavy IDE, which breaks the development flow. Developers want to set breakpoints, step into functions, and inspect variables directly inside VS Code without leaving the editor.

Proposed Capabilities

I propose the integration of the pldebugger extension into the vscode-pgsql workflow, accompanied by a native graphical interface.
The implementation should automate or simplify the following setup steps that are currently manual.

1. OS-Level Package Installation: First, the pldebugger shared library must be installed on the PostgreSQL server machine. The installation method varies significantly by operating system:

• Ubuntu/Debian: sudo apt install postgresql-<version>-pldebugger (e.g., postgresql-16-pldebugger)
• RHEL/Rocky/AlmaLinux: sudo dnf install pldebugger_<version> (e.g., pldebugger_16)
• Windows: the debugger library (plugin_debugger.dll) is bundled with the EnterpriseDB (EDB) PostgreSQL distribution, typically located in: C:\Program Files\PostgreSQL\<version>\lib\plugin_debugger.dll. If using the EDB installer, no additional OS-level installation is required - the library is present by default.

2. PostgreSQL Server Configuration (shared_preload_libraries):
   The debugger library must be loaded at server startup. It cannot be added dynamically.
   Required setting in postgresql.conf.

• Check current setting by executing SHOW shared_preload_libraries;
• Detect the operating system and suggest the correct library path
• If plugin_debugger is not present:
  • Show a warning notification with platform-specific instructions
  • Provide the correct postgresql.conf location for the detected OS
  • Include the exact line to add to the configuration file
  • Guide the user to restart PostgreSQL after configuration changes
  • Provide a "Check Again" button after the user confirms the restart
• Server restart detection: Implement a way to detect if the server has been restarted after config changes (e.g., compare pg_postmaster_start_time before and after)

3. Database Extension Creation
   After the server restart, the debugger API must be enabled in the target database: CREATE EXTENSION pldbgapi;
   Extension Behavior:

• Check if the extension already exists: SELECT * FROM pg_extension WHERE extname = 'pldbgapi';
• If missing, display a prompt: "Debugger API is not installed in this database. Install now?"
• Provide an "Install" button that executes CREATE EXTENSION pldbgapi; in the current connection.
• Show a confirmation upon successful installation.

4. GUI Debugger Interface
Once all prerequisites are satisfied, provide a visual debugger within VS Code:

• Breakpoints: Set/remove breakpoints in .sql or .pgsql files, or directly in the function body editor.
• Debug Controls: Step Over, Step Into, Step Out, Continue, Stop.
• Variables Panel: Inspect local variables, parameters, and their values during execution.
• Call Stack: Show the current execution stack with navigation.
• Parameter Input: When debugging a function, prompt the user to enter parameter values (types, defaults, etc.).
• Output Panel: Display debug output, errors, and execution logs.
• Watch Expressions: Allow users to add custom expressions to monitor

The debugging experience should match the native VS Code Debugger UI (similar to Python, Node.js, or C# extensions), with a dedicated debug view and seamless integration.

Alternatives

• pgAdmin: While it has a functional debugger, it requires running a separate desktop application and a browser. It lacks the tight integration with the code editor that VS Code provides.
• DBeaver: Similar to pgAdmin, it is an external tool. It also relies on the same underlying pldebugger extension but offers a less modern UI compared to VS Code's native debugging experience.

Conclusion

Adding PL/pgSQL debugging with a complete cross-platform setup assistant and graphical interface would significantly enhance vscode-pgsql, making it the ultimate PostgreSQL development tool within VS Code. The three-layer setup (OS package → server config → database extension) is non-trivial, but with proper automation and platform-specific guidance, it becomes accessible to all developers, regardless of their operating system or deployment environment.

Start by reviewing the existing vscode-pgsql workflow and the pldebugger prerequisites described in the issue: server installation, shared_preload_libraries, restart detection, and pldbgapi creation. Define the implementation scope before coding, since the request spans setup automation and a full VS Code debugger UI. Done should include verified prerequisite handling and breakpoint, stepping, variables, call stack, parameters, output, and watch functionality.