pi-tps

Decode throughput for pi: how fast the model is actually generating, in the footer.

<icon> 20 tok/s appears once an assistant message settles, and keeps running for the session. The icon tracks the figure: slow (<100), medium (100–200), full (>200). It needs a Nerd Font; without one the icon renders as tofu.

What it measures

tps = Σ provider output tokens / (Σ decode wall time / 1000)
decode wall time = first output token → settled message

The sums run over the most recent 200 settled messages, so a normal session is cumulative and a long one becomes a rolling readout.

• Decode only. TTFT, queueing, tool execution and retry waits stay out of the denominator, so this reads lower than an end-to-end tokens/second figure.
• Provider tokens. The numerator is the provider's reported usage.output, never a count of stream deltas. A message with no reported usage is skipped, not estimated.
• Time-weighted. Windows are summed before dividing; this is not an average of per-message rates, so a slow answer weighs more than a fast one.
• First token means real output. text_delta, thinking_delta or toolcall_delta carrying a non-empty fragment, or the start of a tool call — the last one counts so a tool call with no argument deltas still gets a first-token time instead of being dropped.
• Cancelled and failed calls are excluded. They settle as messages but assembled no response, so they contribute nothing to the window.
• Settled only. The figure never moves mid-stream; a displayed number is always a complete window.
• One attempt per turn. pi restarts a turn when it auto-retries, so only the attempt that produced the message is measured.

Install

pi install npm:@smoose/pi-tps

Or from a local checkout — point settings at the directory:

{ "extensions": ["/path/to/pi-tps"] }

or symlink it into the auto-discovered directory (/reload picks it up):

ln -s /path/to/pi-tps ~/.pi/agent/extensions/pi-tps

Or run a package once without installing it:

pi -e npm:@smoose/pi-tps

Footer wiring

The extension publishes the tps status key. With @smoose/pi-footer, add a custom item and a segment to ~/.pi/agent/settings.json:

{
  "footer": {
    "segments": ["model", "thinking", "path", "git", "context_pct", "custom:tps", "cost"],
    "customItems": [
      { "id": "tps", "statusKey": "tps", "color": "accent", "hideWhenMissing": true }
    ]
  }
}

hideWhenMissing: true keeps the slot empty until the first message settles. Without a footer extension the key is simply unused; nothing breaks.

State

In memory only. Nothing is written to the session: no custom entries, nothing in the transcript, nothing in /tree. The window is cleared when:

• the process restarts, or /reload, /new, /resume, /fork recreates the session or the extension;
• the model changes — decode speed is a property of the model, and blending two models' samples would make the figure meaningless. Selecting the same model again does not clear it.

/tree navigation deliberately does not clear it: rewinding is not a model change and those tokens were still generated. Auto-compaction does not clear it either.

The window holds the 200 most recent samples, and the oldest drop out beyond that.

Development

bun install
bun run typecheck