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Module gemini

ralph_workflow::json_parser

Module gemini 

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Gemini CLI JSON parser.

Parses NDJSON output from Gemini CLI and formats it for display.

§Streaming Output Behavior

This parser implements real-time streaming output for text deltas. When content arrives in multiple chunks (via message events with delta: true), the parser:

  1. Accumulates text deltas from each chunk into a buffer
  2. Displays the accumulated text after each chunk
  3. Uses carriage return (\r) and line clearing (\x1b[2K) to rewrite the entire line, creating an updating effect that shows the content building up in real-time
  4. Shows prefix on every delta, rewriting the entire line each time (industry standard)

Example output sequence for streaming “Hello World” in two chunks:

[Gemini] Hello\r         (first delta with prefix, no newline)
\x1b[2K\r[Gemini] Hello World\r  (second delta clears line, rewrites with accumulated)
[Gemini] Hello World\n   (final non-delta message shows complete result)

§Single-Line Pattern

The renderer uses a single-line pattern with carriage return for in-place updates. This is the industry standard for streaming CLIs (used by Rich, Ink, Bubble Tea).

Each delta rewrites the entire line with prefix, ensuring that:

  • The user always sees the prefix
  • Content updates in-place without visual artifacts
  • Terminal state is clean and predictable

Structs§

GeminiParser
Gemini event parser