VsCoq

VsCoq communicates with the Coq proof assistant via Language Server Protocol (LSP) to perform real-time, asynchronous proof validation as the user edits or scrolls through `.v` files. In 'Continuous' mode, the extension sends document changes to the `vscoqtop` language server, which incrementally re-checks only affected proof segments rather than re-processing the entire file. This non-blocking approach allows the editor to remain responsive while proof state updates appear in the goal panel.

VsCoq's default mode processes Coq files sequentially from top to bottom, checking each proof definition and tactic step on demand. The extension sends cursor position or explicit step commands to `vscoqtop`, which returns the proof state (goals, context, hypotheses) for display in the goal panel. This mode gives users explicit control over proof progression and is suitable for understanding proof structure incrementally.

VsCoq depends on the `vscoq-language-server` package, which must be installed via opam (OCaml package manager) in a Coq-enabled opam switch. The extension expects the `vscoqtop` executable to be discoverable in the system PATH or configured via the 'Vscoq: Path' setting. The extension manages the language server lifecycle (startup, shutdown, error recovery) through LSP, but does not manage opam or package installation; users must manually set up the opam environment.

VsCoq renders the current proof state (goals, context, hypotheses) in a dedicated goal panel within VS Code's sidebar or editor area. The panel supports two display modes: accordion lists (collapsible goal sections) and tabs (one goal per tab). The extension receives goal data from `vscoqtop` via LSP and formats it for display, allowing users to inspect proof state without leaving the editor.

VsCoq provides a dedicated query panel that accepts Coq commands (Search, Check, About, Locate, Print) and sends them to `vscoqtop` for execution. The panel displays results and maintains a session-scoped history of queries, allowing users to explore the proof environment, inspect definitions, and search for theorems without leaving the editor. Queries are executed asynchronously and results appear inline in the query panel.

VsCoq provides TextMate-based syntax highlighting for Coq source code (`.v` files), colorizing keywords, tactics, types, comments, and identifiers according to Coq language grammar. The extension integrates with VS Code's syntax highlighting engine to apply color schemes and font styles based on token classification, enabling visual distinction between proof constructs and improving code readability.

VsCoq acts as an LSP client that communicates with the `vscoqtop` language server (a separate OCaml/Coq package) via JSON-RPC over stdio. The extension sends document changes, cursor positions, and query commands to the language server, which invokes the Coq proof assistant and returns proof state, diagnostics, and query results. This client-server architecture decouples the editor from the proof assistant, enabling responsive UI and background proof checking.

VsCoq respects the Coq module system and project structure, allowing the language server to resolve imports and dependencies across multiple `.v` files in a workspace. The extension maintains awareness of the current project's Coq modules, enabling queries and proof checking to access definitions from imported libraries and dependencies. This is managed through the opam switch and Coq's library path configuration.

VsCoq receives diagnostic messages from `vscoqtop` (syntax errors, type mismatches, proof failures) and displays them inline in the editor as squiggly underlines, error messages, and diagnostic tooltips. Diagnostics are updated asynchronously as the user edits or the proof checker processes changes, providing real-time feedback on proof validity without requiring manual error checking.

VsCoq exposes configuration options in VS Code's settings panel, allowing users to specify the path to the `vscoqtop` executable and select the proof checking mode (Continuous vs. step-by-step). These settings are stored in VS Code's configuration system and applied when the extension initializes, enabling per-user or per-workspace customization without editing configuration files.

VsCoq registers extension commands in VS Code's command palette (accessible via F1 or Ctrl+Shift+P), allowing users to trigger proof-related actions (e.g., step forward, step backward, restart language server) without memorizing keybindings. Commands are discoverable through the palette's search and can be bound to custom keybindings by users.