pi-model-modes

A pi extension that adapts the system prompt per model and per behavioral mode.

Every turn it tells the model what it is — You are {model.name} from {provider}. — read live from ctx.model, and (when a mode is selected) splices a composable mode into pi's assembled system prompt. It transforms pi's prompt rather than replacing it: tools, skills, <project_context>, and date/cwd all survive. With no mode selected, only the identity line is added.

The assembled prompt is byte-stable across turns where nothing relevant changed (a per-turn cache key over model + mode signature + pi's base keeps provider prefix caches warm).

Install

This is a pi package (pi-package keyword + pi manifest in package.json, entry at extensions/index.ts).

pi install npm:@nklisch/pi-model-modes

# From this monorepo — edits hot-reload via /reload during development
pi install /absolute/path/to/pi-extensions/packages/pi-model-modes

# Or try it for the current run only, without writing to settings
pi -e /absolute/path/to/pi-extensions/packages/pi-model-modes

pi install writes the package into your settings.json packages list; the extension is then auto-loaded on every session.

Using modes

A mode composes one base voice + one value from each of three axes (agency × quality × scope) + zero or more modifiers. A preset is a named bundle of those choices, applied atomically.

Commands

| Command | Effect | |---|---| | /mode | Show the effective mode (its source tier + composed axes) and the available presets. Display-only — triggers no turn. | | /mode <preset> | Set the mode for this session (an ephemeral override). Unknown presets surface an error and leave the prior mode intact. | | /mode none | Set a virtual no-mode override for this session. It injects no mode fragments and still wins over the config default. | | /mode off | Clear the session override; falls back to the config default (or unset). | | /mode default | Show the durable default configured in global + project config files, and which scope wins. Display-only — triggers no turn. | | /mode default <preset> | Set the project default mode in <cwd>/.pi/pi-model-modes.json. Use none to make "no mode" the durable project default. | | /mode default <preset> --global | Set the global default mode in ~/.pi/agent/pi-model-modes.json. --global may appear before or after the preset. | | /mode default off [--global] | Clear the default in project scope (or global scope with --global); after clearing project scope, any global default becomes effective again. |

/mode:inspect shows the effective mode, the derived identity line, when/why the prompt last changed, and the current cache key — useful for debugging cache behavior or a stuck mode. Add --prompt to append the full assembled system prompt in a fenced block. The prompt view uses the most recent pi base prompt seen by the turn handler; if no turn has run yet it reports that the base prompt has not been populated rather than guessing.

Footer indicator

The effective mode is shown in pi's footer as mode: <glyph> <summary> under this package's own pi-model-modes status key. The glyph is ◆ for pi/default voice, ◇ for chill, ⬡ for flow, and ✕ when the current mode is unresolvable. The text then shows the preset/voice summary plus +N when modifiers are active; an unset state renders like mode: ◆ unset. In TUI mode the label, glyph, value, and hint use pi's active theme tokens, so Catppuccin flavors inherit their own colors cleanly.

When keyboard cycling is enabled, the footer also adds the cycle hint: ctrl+shift+u/ctrl+shift+alt+u cycle.

Keybindings

No mode-cycle shortcut is registered by default. Mode changes are made with /mode; this avoids terminal control-character collisions such as Ctrl+M, which is encoded like Enter in legacy terminal input.

To opt into keyboard cycling, set cycleKeybinding: true in the global config file (~/.pi/agent/pi-model-modes.json). This registers Ctrl+Shift+U to cycle forward and Ctrl+Shift+Alt+U to cycle backward through the preset list, and enables the footer cycle hint.

Config default

A durable default mode can be set either with /mode default … or by editing a plugin-owned config file directly (separate from pi's closed settings.json, which has no plugin namespace). Two files are read project over global; scalar keys shallow-merge, while customStyles merges per name:

• global: ~/.pi/agent/pi-model-modes.json
• project: <cwd>/.pi/pi-model-modes.json

Shape (v1):

{ "defaultMode": "flow" }

The command surface mirrors that merge model:

/mode default flow          # write project default
/mode default --global flow # write global default
/mode default none          # project-level durable no-mode, masking any global default
/mode default off           # clear project default; global may become effective
/mode default off --global  # clear global default

Autocomplete surfaces --global as the first choice after /mode default and continues with preset completion after /mode default --global . The bare /mode panel also prints both durable forms so persistence is discoverable without reading documentation.

Writes preserve sibling keys such as cycleKeybinding, format JSON with two-space indentation, and refuse to overwrite malformed/non-object JSON files. An invalid defaultMode (unknown preset / missing fragment) warns and is skipped during session start; command-time writes validate before touching disk.

Writing styles

An optional writing style controls conversational communication independently of the active mode. Bundled styles are clear, compact, explanatory, expressive, and straight. straight leads with direct technical judgment, removes sugarcoating and false balance, and keeps explanations self-contained.

| Command | Effect | |---|---| | /style | Show the effective selection, selection tier, fragment provenance, and style catalog. Display-only — triggers no turn. | | /style <name> | Set a temporary session override. | | /style none | Explicitly suppress style injection for this session, masking any configured default. | | /style off | Clear the session override and reveal the project/global default or unset state. | | /style default | Show global, project, and effective durable style defaults. Display-only — triggers no turn. | | /style default <name|none> | Set the project default; none durably masks a global style. | | /style default <name|none> --global | Set the global default; --global may appear before or after the value. | | /style default off [--global] | Delete writingStyle from the selected scope; clearing project scope may reveal the global default. |

For example:

/style expressive                 # temporary experiment
/style default clear              # persistent project default
/style default --global compact   # persistent global default
/style none                       # temporarily mask either default
/style off                        # reveal the configured default
/style default off                # clear project default; reveal global
/mode straight                       # direct premise-checking behavior
/style straight                      # direct, self-contained prose

The straight mode and style are independent. Use either one alone, or select both when you want the behavioral base and the writing posture together.

The same durable selection can be edited directly in config:

{
  "defaultMode": "flow",
  "writingStyle": "team-voice",
  "customStyles": {
    "team-voice": "styles/team-voice.md"
  }
}

Custom paths must be relative .md files contained within the defining config directory; absolute paths, escapes, and escaping symlinks are rejected. Global and project maps merge per key, with project entries winning. Custom style names cannot be none, off, or default because those tokens belong to the command grammar.

Styles inject even when no mode is active, after identity and before mode fragments. They affect only conversational communication with the user. They do not control code or code comments, authored project documentation, tool use, autonomy, edit scope, or problem-solving/implementation strategy. /mode:inspect reports selection provenance separately from bundled/custom fragment provenance.

Mode precedence: session override (/mode) > config default > unset. The override is ephemeral (in-memory, not written to disk): a genuinely new session (/new, /resume, /fork) restarts from the config default, while a same-session /reload or startup keeps any active override. Changing the default does not clear an active override; run /mode off to let the default take effect immediately.

Mode reference

Base voice (default pi = no overlay, identity only):

• pi — no voice overlay
• chill, flow, pi-direct, straight — overlay voices (prompts/base/*.md)

Agency — autonomous · collaborative · surgical · partner

Quality — architect · pragmatic · minimal

Scope — unrestricted · adjacent · narrow

Modifiers (zero or more) — bold · tdd · debug · flow · muse · readonly · methodical · director · speak-plain · context-pacing · playful

Built-in presets

| Preset | base | agency | quality | scope | modifiers | |---|---|---|---|---|---| | create | pi | autonomous | architect | unrestricted | — | | extend | pi | autonomous | pragmatic | adjacent | — | | safe | pi | collaborative | minimal | narrow | — | | refactor | pi | autonomous | pragmatic | unrestricted | — | | explore | pi | collaborative | architect | narrow | readonly | | debug | chill | collaborative | pragmatic | narrow | debug | | methodical | chill | surgical | architect | narrow | methodical | | director | chill | collaborative | architect | unrestricted | director | | partner | chill | partner | pragmatic | adjacent | speak-plain, tdd | | muse | chill | autonomous | architect | unrestricted | muse | | flow | flow | autonomous | architect | adjacent | flow | | tinker | flow | autonomous | pragmatic | unrestricted | flow, playful | | spark | chill | autonomous | architect | unrestricted | muse, playful | | straight | straight | autonomous | pragmatic | adjacent | — | | none | — | — | — | — | virtual no-mode override |

Preset definitions live in presets.json, except none, which is virtual and injects no mode fragments. The fragment text lives in prompts/ (base/, axis/{agency,quality,scope}/, modifiers/). Fragment files are cached by mtime, so editing one takes effect on the next turn — no /reload needed. The straight base was adapted from the intent of claude-code-modes: correctness over agreement, explicit premise checking, and direct criticism of the work without turning abrasiveness into a persona.

How it works

• Identity is additive. You are {model.name} from {provider}. is prepended as the very first line on every turn — including mode-unset turns and turns with a custom SYSTEM.md / --system-prompt. It never overrides or removes the user's base content.
• Assembly is deterministic. Within the splice, order is fixed: identity → optional writing style → base voice → agency → quality → scope → modifiers (in preset-declared order) → pi's assembled base.
• Cache-stable. The handler computes a cache key each turn over model.name + model.id + model.provider + the mode signature + the style signature + a hash of pi's base, and only re-assembles on a miss. There are no timestamps, counters, or nondeterministic values in the assembled output, so consecutive no-change turns produce byte-identical prompts.
• No-op when unset. With no mode or style selected, only the identity line is prepended; the legacy bytes after it are unchanged.
• Modes are advisory for spawned subagents. Mode fragments splice into the main session's system prompt. When you spawn a subagent (e.g. via pi's subagent tool), the agent's own definition file (its *.md under ~/.pi/agent/agents/) is appended after the mode fragments, so on any conflict the agent's hardcoded posture wins. Selecting /mode surgical will not, for example, override the implementor agent's designed refactor scope — modes retune the conversation you're in, not the specialists you delegate to.

The hard contract (invariants, cache key, resolution precedence) is documented in docs/SPEC.md; the component layout and per-turn flow are in docs/ARCHITECTURE.md.

Development

• Runtime: Node >= 22.19.0
• Install: npm install
• Test: npm test
• Typecheck: npm run typecheck

The registration surface is a single factory in extensions/index.ts — the before_agent_start handler, /mode, /mode:inspect, and /style commands, plus session_start config and TUI autocomplete handlers. All logic lives in plain modules under src/ with no pi coupling except through typed interfaces, which keeps it unit-testable without spinning up pi (tests under tests/).