Source-visible curiosities
ultrathink is a real trigger
The code does not just mention ultrathink in prompts. src/utils/thinking.ts includes explicit helpers to:
- detect the keyword
- locate its positions in text
- gate the feature behind both build and rollout switches
REPL mode hides primitive tools
src/tools/REPLTool/constants.ts defines a REPL_ONLY_TOOLS set that hides read, edit, write, grep, glob, bash, notebook-edit, and agent-style primitives when REPL mode is active.
Embedded search can remove grep/glob tools entirely
src/tools.ts includes a build optimization where GlobTool and GrepTool disappear if the Bun binary already ships embedded search helpers.
There is a buddy/ subtree
The repository includes a src/buddy/ area, which is one of the more visibly playful product surfaces in the tree.
Internal-only command surface is large
src/commands.ts carries a substantial list of internal-only commands that never ship to normal external builds.