@pi-unipi/fusion

Local Fusion for UniPi: a Devin-inspired lead + persistent sidekick pair, a curated model preset, and a keyboard-first picker (/unipi:model). It uses pi's extension and RPC APIs natively.

/unipi:model — the picker

╭ Model ───────────────────────────────────────────────────────────────╮
│/ Type to search                                                       │
│───────────────────────────────────────────────────────────────────────│
│❭ Fusion                              ← ▰▰▰▱▱ → Medium  Lead Fable… ▾ │
│· GLM-5.3 Flash ✱                        ▰▰▰▰▰   Max                │
│· openrouter · deepseek/deepseek-v4.1-flash ▰▰▱▱▱   High              │
│  ↓ more below                                                        │
│                                                                       │
│  ━━━━━●━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━               │
│  Input      Cached input   Output     Sidekick input                 │
│  $10 / 1M   $0.25 / 1M     $50 / 1M   $0.2 / 1M                     │
│  Sidekick cached input   Sidekick output                             │
│  $0.02 / 1M              $1.2 / 1M                                   │
│  Model key  openrouter/deepseek/deepseek-v4.1-flash                  │
│                                                                       │
│  ✱ New  ✱ Promotion  ✱ Beta · Pairs frontier intelligence with cost-efficient execution │
│↑↓ select · tab lead · ←→ effort · ↵ confirm · esc cancel              │
╰───────────────────────────────────────────────────────────────────────╯

• Row order: the active selection pinned first, then the Fusion row (when a pair is configured), then recent (≤5, MRU), then the preset models, then every other available model — the catalogue is never hidden; the preset only controls ordering. When a single model is selected its row lights up with ✓; when Fusion is selected the selection lives on the Fusion row and plain rows stay unmarked.
• ←/→ steps the highlighted row's effort (pi thinking level: off → minimal → low → medium → high → xhigh → max) and it is remembered per model. The five-cell bar fills with ▰ and uses ▱ for remaining levels. The Fusion row keeps its own lead/sidekick efforts, so adjusting Fusion never rewrites a model's standalone level.
• tab on the Fusion row cycles focus: effort → lead → sidekick (shift+tab reverses). Focused columns open an inline dropdown over the preset lists; ↵ applies, esc collapses.
• Price panel: the highlighted model's blended price is marked on a logarithmic red→orange→yellow→green→cyan→blue→violet slider. Fusion shows Input, Cached input, Output, Sidekick input, Sidekick cached input, and Sidekick output, and the exact registry key of the highlighted row is spelled out (Model key openrouter/deepseek/deepseek-v4.1-flash; both the lead and sidekick keys on the Fusion row).
• Name column & provider: the name column sizes itself to the widest row label (minimum 24 columns) up to the terminal width, and the effort control stays right-anchored — so wide terminals show full names. A row only gets a dim provider · prefix when its display name is ambiguous: it contains a / (deepseek/deepseek-v4.1-flash reads like a key) or the same friendly name is offered by more than one provider. Unique names stay clean, and the prefix is never truncated.
• Confirm applies: pi.setModel, pi.setThinkingLevel(effort), updates MRU + persisted active selection, and shows Fusion · Lead ◆ Sidekick in the footer. Switching the model through pi's own /model/Ctrl+P drops Fusion mode.
• Because pi intercepts /model inside its editor before extensions run, the command cannot be replaced — instead typing /model pins /unipi:model as the first autocomplete suggestion.
• Fast Mode is not implemented because pi has no equivalent capability.

Hand-edited preset badge metadata renders ✱ as New, Promotion, or Beta:

{"badges": {"provider/model": "new"}}

/unipi:fusion-preset — curation

Two-column checklist over every available model:

╭ Fusion preset ───────────────────────────────────────────────────────╮
│Fusion preset · 2 lead · 2 sidekick · writes to global                │
│Search: (type to filter)                                               │
│    L   S    model                                                     │
│ › [x] [ ]  provider/lead                                              │
│   [ ] [x]  provider/sidekick                                          │
│↑↓ select · ←→ column · space toggle sidekick · Enter save · esc cancel │
╰───────────────────────────────────────────────────────────────────────╯

• ←/→ (or tab) switches the L/S column, space toggles membership, Enter saves & closes, esc cancels, and typing filters. Selected models float to the top so the curated set is always visible.
• Defaults are not edited here: confirming a Fusion pair in /unipi:model records it as the preset default.

Any model key in the registry is allowed — there is no OAuth/subscription gate.

Persistent sidekick

Confirming a Fusion pair selects the lead for the session. The sidekick tool runs one lazy-spawned child pi per lead session; its session file is persisted at ~/.unipi/state/fusion/sidekick/<lead-session-id>.jsonl. Context and shells persist across handoffs. The sidekick's context compacts independently of the lead's (it is its own pi session). sidekick({message, block:true}) waits by default; block:false returns immediately and delivers a <subagent_completion_notification>. Calling it while busy steers the same handoff. A handoff whose lead turn has ended — started with block:false, abandoned by a user message, or timed out — still wakes the lead with that same completion notification when its report lands, exactly once. Background tasks keep that handoff open through their completion notification and any follow-up turn, so the report is not released at an intermediate checkpoint. If a prompt arrives while the child is processing, Fusion retries it once with pi's followUp streaming behavior. Sidekick work renders as ordinary tool activity — handoff ids, agent_id, and read_subagent protocol text never reach the terminal. Sidekick output keeps that same format on the main surface, marked as sidekick-origin by a ▍ rail. While the sidekick works and the lead's turn is over, an animated sidekick working line above the editor shows the live tool count and elapsed time until the report lands. read_subagent({agent_id?, block?, timeout?}) reads or waits for a handoff.

The child receives UNIPI_FUSION_CHILD=1 and UNIPI_SUBAGENT_CHILD=1; the Fusion extension guard prevents child processes from registering Fusion tools, commands, or lead policy.

The lead gets the persistent delegation policy through before_agent_start, and the first direct edit/write receives a one-time delegation nudge. /unipi:fusion-stats reports sidekick tokens, costs at sidekick and lead rates, estimated savings, handoff count, and runtime state. The footer shows savings above $0.005.

Storage

// ~/.unipi/config/fusion/preset.json (global)
// <cwd>/.unipi/fusion-preset.json    (project override; lists replace, objects merge)
{
  "schema_version": 1,
  "lead": ["provider/lead"],
  "sidekick": ["provider/sidekick"],
  "default": {"lead": "provider/lead", "sidekick": "provider/sidekick"},
  "effort": {"provider/sidekick": "high"},
  "badges": {"provider/sidekick": "new"},
  "prices": {"provider/sidekick": {"input": 0.2, "cachedInput": 0.02, "output": 1.2}},
  "recent": ["provider/lead"],
  "active": {"kind": "fusion", "lead": "provider/lead", "sidekick": "provider/sidekick"}
}

prices is an optional manual override for models whose provider reports no pricing.

Status

• [x] Preset store, project layering, curation UI, autocomplete boost
• [x] Picker effort bars, price slider, price panel, badges, legend
• [x] Persistent sidekick runtime, blocking/non-blocking tools, steering, progress, completion card, session isolation
• [x] Lead policy, first-edit nudge, savings estimate, footer and stats command