@pify/btw

By-the-way side conversations for pi: ask a read-only, codebase-aware side agent anything while the main agent keeps working — without derailing the session or polluting its context.

Part of the Pify suite. Install with pify install btw or pi install npm:@pify/btw.

Why

Halfway through a long task you want to know something — what does this helper actually do, is there a test for this path, why is that config shaped that way. Asking the main agent costs you twice: the question and its answer stay in the context forever, and the agent you interrupted now has to find its way back to what it was doing.

A side conversation answers the question somewhere else. It reads the same codebase, it never writes, and the main thread never sees it unless you decide it should.

Commands

| Command | Description | |---|---| | /btw [--save] <question> | Ask in the current side thread, which inherits the main session's context. --save also writes the exchange as a visible session note — saved silently, never provoking a main-agent turn even mid-task. | | /btw:new [question] | Start a fresh side thread. | | /btw:tangent [--save] <question> | A contextless side thread — no main-session context, fresh perspective. Switching between /btw and /btw:tangent clears the thread. | | /btw:clear | Dismiss the widget and clear the thread. | | /btw:inject [instructions] | Send the full thread to the main agent — queued as a follow-up if it is busy — then reset. | | /btw:summarize [instructions] | Summarise the thread with a model, send the summary to the main agent, then reset. Refused while a side answer or another summarize is still running. | | /btw:model [<provider> <model> <api> \| clear] | Show or set a BTW-only model override. | | /btw:thinking [off\|minimal\|low\|medium\|high\|xhigh\|max \| clear] | Show or set a BTW-only thinking override. |

How it works

Each side question runs in an in-memory pi sub-session, seeded in contextual mode with the main session's conversation. It inherits your project's system prompt and context files but loads no extensions — so it cannot recurse — and only read-only tools: read, grep, find, ls.

Answers stream into a widget above the editor, and it works while the main agent is busy.

Completed exchanges are persisted as hidden custom entries in the session file: visible to you in the widget, invisible to the main agent, and rebuilt into a thread on restart. Model and thinking overrides are persisted per session the same way. A saved --save note is never fed back into a later side session either — the side agent does not re-read its own notes.

The widget shows a reasoning model's thinking only while it streams (just the tail), then collapses it to a 💭 thought N lines marker once the answer lands, so a long reasoning block never pushes the editor off-screen.

Cancelling or clearing BTW aborts only the sub-session. It never touches the main agent's turn. Changing the model or thinking level mid-answer cancels the in-flight side question (it is not persisted) and tells you so; finished exchanges stay.

Honest about what it cannot do

A model with no write tool will sometimes narrate the edit anyway, or print tool-call JSON as text. Nothing happens on disk, but the widget reads as though something did — and /btw:summarize would carry that fiction into the main session, where it becomes something the main agent believes.

So: emitted tool-call syntax is stripped, an answer that still claims a change gets a read-only side conversation: nothing was changed footer, and the summariser is instructed to describe proposals as proposals.

Cheaper questions

/btw:model and /btw:thinking run side questions on a smaller model or a lower thinking level than the main thread. A question about where something lives does not need the model you are paying for the refactor.

Development

bun install
bun test              # unit tests over the pure modules, plus command tests against a stub host
bunx tsc --noEmit     # strict typecheck, including the extension entry
pi -e .               # load into a live pi session

Requires Node >= 22.19.0 or Bun for development. At runtime pi loads the raw TypeScript through jiti.

License

MIT © Pify maintainers