Architecture Overview

Three processes split the work. Only the daemon touches files, Git or indexes.

flowchart LR
  subgraph VSCode["VS Code / code-server"]
    WV["Webview<br/>search panel · help · welcome"] -- "postMessage" --> EH["Extension host"]
  end
  EH -- "JSON-RPC 2.0 over stdio" --> RPC
  subgraph Daemon["Search daemon (Go) · one per window"]
    RPC["rpc + server"] --> Q["query<br/>parser + planner"]
    Q -- Plan --> TE["trigram<br/>working-tree engine"]
    Q -- Plan --> HE["history<br/>commit engine"]
    IX["indexer<br/>only writer"] -- "published snapshots" --> TE
    IX -- "published snapshots" --> HE
  end
  IX --> DISK[("index.location<br/>on disk")]

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Who owns what

Part	Owns	Never
Webview	Rendering, debouncing, fix-its and completions as text edits	Reads files, calls Git, reaches the daemon, parses queries
Extension Host	Commands, keybindings, settings, spawning the daemon, opening editors	Searches, parses, or keeps results past the current list
Daemon: rpc, server	Request lifecycle, cancellation, search IDs, batching	Reads or writes an index
Daemon: query	Grammar, diagnostics, fix-its, completions, planning	I/O beyond author and repo lookups
Daemon: trigram, history	Results and previews for files and commits	Writes an index
Daemon: indexer	Building, refreshing and publishing both indexes	Answers searches

One query, one engine

The planner sends each query to exactly one engine:

Query has…	Engine	Results
Text, file:, language:, symbol:, type:file, since:, until:	Working tree (trigram)	File names, code lines, symbol definitions
author:, message:, type:commit	History (history)	Commits whose changed lines or message match
type:added, type:removed	History (history)	Commits whose added (or removed) lines match

Next

• Search Flow: what happens on each keystroke
• Protocol: the messages between processes
• Indexing: how the indexes are built and kept fresh