Navigating the codebase like a developer: f12/symbolic navigation tools

[OmerMachluf]

This is an exploration PR: It is not fully ready yet.
The core idea behind it is to reduce the number of text searches which are expensive, yield many results and limit the capability to work properly in big/huge repositories.
Instead, this aims to provide tools for copilot that allows him to navigate the codebase like a developer would.
It leverages LSP to provide code referneces, f12 capability, find references/implementations etc or get the document full symbols to understand structure and allow to focus on which lines to read beforehand.
I haven't done official benchmarking yet(And I was curious if there are any suites already designed for that purpose), but from my own internal tests I am able to complete tasks that would have usually yielded or give up due to context loss or too many searches yielding nothing.
Execution happens faster and more realibly as the copilot simply navigates between documents he's exploring or modifying using semantic references.
I wanted to get a ack that there are no blockers with this approach before doubling down on the time allocated to complete this fully.
Among the gaps that I currently recognize are:

• Official benchmarking test suites(if any) validation based more on mere my own experience
• Experimental flag: having this as an opt-in rather than enabled by default
• having fallback for languages or workspaces without lsp support or when language symbols are not loaded yet
• Refining the prompt as sometimes i find myself reminding it to use symbolic navigation over search while symbolic navigation works faster and more reliably

[OmerMachluf]

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[Copilot]

Pull Request Overview

This PR introduces symbolic navigation tools that enable the AI to navigate codebases like a developer using F12-style navigation (Go to Definition, Find References, Find Implementations) along with document symbol listing capabilities.

Key Changes

• Added four new language model tools: DocumentSymbols, Definitions, Implementations, and References
• Implemented shared utilities for symbol position normalization and ambiguity resolution
• Updated agent prompts to instruct the AI on when and how to use symbolic navigation tools

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
src/extension/tools/node/definitionsTool.tsx	New tool implementing "Go to Definition" functionality with symbol disambiguation
src/extension/tools/node/implementationsTool.tsx	New tool for finding concrete implementations of interfaces/abstract members
src/extension/tools/node/referencesTool.tsx	New tool for finding all references to a symbol across the workspace
src/extension/tools/node/documentSymbolsTool.tsx	New tool for listing document symbols with pagination and caching support
src/extension/tools/node/toolUtils.ts	Added shared utilities for symbol position normalization and disambiguation
src/extension/tools/node/allTools.ts	Registered the four new navigation tools
src/extension/tools/common/toolNames.ts	Added enum entries and tool categories for the new tools
src/extension/tools/vscode-node/tools.ts	Added debug logging for tool registration
src/extension/prompts/node/panel/codebaseAgentPrompt.tsx	Added instructions for using symbolic navigation tools in codebase agent
src/extension/prompts/node/agent/defaultAgentInstructions.tsx	Added instructions for symbolic navigation in default and alternate GPT prompts
package.json	Added JSON schemas for the four new tools with complete parameter definitions
package.nls.json	Added localized strings for tool names and descriptions

[Copilot]

The sentence starts with lowercase "you" after a period. It should be capitalized: "You must use the line number..."

Suggested change

	Use {ToolName.Definitions} When you know where you are in the file, use {ToolName.Definitions} to navigate straight to the target symbol, just like a developer would use f12. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.Implementations} to enumerate concrete implementations when working or modifying with interfaces and you need to recognize their usages. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.References} to find referenced usages of a symbol across the codeobase. very useful when modifying public functions signatures or data structures. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Use {ToolName.Definitions} When you know where you are in the file, use {ToolName.Definitions} to navigate straight to the target symbol, just like a developer would use f12. You must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.Implementations} to enumerate concrete implementations when working or modifying with interfaces and you need to recognize their usages. You must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.References} to find referenced usages of a symbol across the codeobase. Very useful when modifying public functions signatures or data structures. You must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />

[Copilot]

The sentence starts with lowercase "you" after a period. It should be capitalized: "You must use the line number..."

Suggested change

	Use {ToolName.Definitions} When you know where you are in the file, use {ToolName.Definitions} to navigate straight to the target symbol, just like a developer would use f12. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.Implementations} to enumerate concrete implementations when working or modifying with interfaces and you need to recognize their usages. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.References} to find referenced usages of a symbol across the codeobase. very useful when modifying public functions signatures or data structures. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Use {ToolName.Definitions} When you know where you are in the file, use {ToolName.Definitions} to navigate straight to the target symbol, just like a developer would use f12. You must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.Implementations} to enumerate concrete implementations when working or modifying with interfaces and you need to recognize their usages. You must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.References} to find referenced usages of a symbol across the codeobase. Very useful when modifying public functions signatures or data structures. You must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />

[Copilot]

The instanceof Location check may not work correctly. Since Location is imported from the vscode API, checking instanceof may fail when the location comes from a different execution context. Consider checking for the presence of expected properties instead: 'uri' in location && 'range' in location or use a type guard.

Suggested change

	return locations.map(location => location instanceof Location ? location : new Location(location.targetUri, location.targetSelectionRange ?? location.targetRange));
	return locations.map(location => ('uri' in location && 'range' in location) ? location : new Location(location.targetUri, location.targetSelectionRange ?? location.targetRange));

[Copilot]

The sentence "very useful when modifying..." should start with a capital letter: "Very useful when modifying..."

Suggested change

	Call {ToolName.References} to find referenced usages of a symbol across the codeobase. very useful when modifying public functions signatures or data structures. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />
	Call {ToolName.References} to find referenced usages of a symbol across the codeobase. Very useful when modifying public functions signatures or data structures. you must use the line number and symbol name as received from the {ToolName.DocumentSymbols} tool.<br />

[Copilot]

Debug console.log statements should be removed or replaced with proper logging using the project's logging infrastructure. The extension should use the logging service from src/extension/log/ instead of console.log for production code.

[Copilot]

Missing line break. According to the TSX coding guidelines, <br /> should be used for line breaks. Add <br /> at the end of this line to properly separate it from the next instruction.

[Copilot]

Missing line break. According to the TSX coding guidelines, <br /> should be used for line breaks. Add <br /> at the end of this line to properly separate it from the next instruction.

[Copilot]

Inconsistent indentation. According to the coding guidelines, tabs should be used for indentation. This line uses tabs but is misaligned with the surrounding code. The opening brace should align with the lines above it at lines 224 and 267.

[Copilot]

The instanceof Location check may not work correctly. Since Location is imported from the vscode API, checking instanceof may fail when the location comes from a different execution context. Consider checking for the presence of expected properties instead: 'uri' in location && 'range' in location or use a type guard.

Suggested change

	function normalizeLocations(locations: readonly (vscode.Location | vscode.LocationLink)[]): Location[] {
	return locations.map(location => location instanceof Location ? location : new Location(location.targetUri, location.targetSelectionRange ?? location.targetRange));
	function isLocation(obj: any): obj is Location {
	return obj && typeof obj === 'object' && 'uri' in obj && 'range' in obj;
	}
	function normalizeLocations(locations: readonly (vscode.Location | vscode.LocationLink)[]): Location[] {
	return locations.map(location =>
	isLocation(location)
	? location
	: new Location(location.targetUri, location.targetSelectionRange ?? location.targetRange)
	);

[Copilot]

Unused variable tools.

Suggested change

const tools = detectToolCapabilities(this.props.availableTools);

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