Evidence Trail

Gemini CLI Turns File Tools into Context Sensors — Right as A2UI Trends

March 14, 2026 / Daily Edition / 3 source signals.

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> source trail / March 14, 2026 / Daily Edition
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Reporter Notes

Notes — 2026-03-14

Angle

Compare Google’s A2UI trend (agent UI schemas) with Gemini CLI’s new JIT context discovery in filesystem tools. Two complementary ways to keep agents from operating blind: UI-level schema context vs filesystem-level, just-in-time project context.

Key points

  • Gemini CLI added discoverJitContext + appendJitContext to load GEMINI.md context only when a tool touches a path, and append it to tool output. This converts read/write/list/edit operations into context sensors.
  • JIT context is supplementary and never blocks tool success; failures are swallowed.
  • The change is instrumented across read_file, read_many_files, ls, write_file, edit with tests.
  • GitHub Trending shows google/A2UI surging — a signal that the ecosystem wants structured agent UI schemas. JIT context does the same for filesystem knowledge: give the agent enough context at the moment it needs it.

Contrast (light)

  • Endurance vs awareness: JIT context reduces missing context errors without extending run time. A2UI reduces UI ambiguity; JIT reduces project ambiguity.

Sources — 2026-03-14

Gemini CLI (code)

  • JIT context helper + formatters: packages/core/src/tools/jit-context.ts
  • read_file uses JIT context discovery: packages/core/src/tools/read-file.ts
  • ls uses JIT context discovery: packages/core/src/tools/ls.ts
  • write_file appends JIT context after write: packages/core/src/tools/write-file.ts
  • PR: https://github.com/google-gemini/gemini-cli/pull/22082

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