Pi - @agntn/harnesses

IDpi13 / 1313 paths · env + project

Harness

Pi Coding Agent

Every invocation mode, native model listing with search. The reference harness here.

Invoke: 6 of 6 · official
Models: native listing
MCP: json · pi
Agents file: ~/.pi/agent/AGENTS.md

Inferred 0 / 13

Access

GetgetHarness("pi")

CLIharnesses paths pi --json

Trypi in the explorer

Pi is the reference harness for this package, because it supports everything: --no-tools for the advisor, --tools read,grep,find,ls for a read-only agent, --mode json for structured output on all of them, --model for selection and --list-models with an optional fuzzy filter. listModels parses that output into the shared AvailableModel shape; it lists only providers with configured authentication, so an empty result is a credentials question, not a bug.

Sessions are JSONL per project under ~/.pi/agent/sessions/, with UUIDv7 ids, and the directory moves with PI_CODING_AGENT_SESSION_DIR or --session-dir. .pi/SYSTEM.md replaces the system prompt and APPEND_SYSTEM.md appends to it. .pi/prompts/ holds reusable Markdown prompts invoked as slash commands, so those paths appear in both promptTemplates and commands. The Pi extension in this package registers the eleven tools in Pi itself.

MCP servers? Since 0.99 Pi has them built in, in ~/.pi/agent/mcp.json and .pi/mcp.json. The project file counts only once you trust the project. sse is out, Pi wants stdio or streamable HTTP.

Capabilities and invocation

mcp: yes
vision: yes
audio: no
video: no
tools: yes
streaming: yes

Binary pi, evidence official. Add --mode json for structured event output. Model selection appends --model {model}.

Callinvoke(prompt, options)6 of 6 modes

advisor{}-p --no-tools {prompt}
advisor · json{ structured: true }-p --no-tools --mode json {prompt}
read-only{ readOnly: true }-p --tools read,grep,find,ls {prompt}
read-only · json{ readOnly: true, structured: true }-p --tools read,grep,find,ls --mode json {prompt}
agent{ tools: true }-p {prompt}
agent · json{ tools: true, structured: true }-p --mode json {prompt}

Model listing runs pi --list-models and --list-models {search} with a filter. Lists models with configured provider authentication; accepts an optional fuzzy search.

Paths

Templates as the registry stores them. ~, ${HOME}, ${TMPDIR} and %VAR% expand in resolve(); entries tagged with a platform are dropped on the others. Open in the explorer to see them expanded for a home directory of your choice.

PathsgetHarness("pi")13 templates · 6 groups

config

~/.pi/agent/settings.jsonuserofficialall
.pi/settings.jsonprojectofficialall

sessions

~/.pi/agent/sessions/<dash-encoded-cwd>/<timestamp>_<session-id>.jsonldataofficialall
Per-project session transcripts in JSONL format; session ids are UUIDv7. Overridable with --session-dir.

instructions

AGENTS.mdprojectofficialall
Loaded from parent directories and cwd; CLAUDE.md accepted as an alternative, AGENTS.override.md takes precedence over both in a directory.
.pi/SYSTEM.mdprojectofficialall
Replaces the default system prompt; APPEND_SYSTEM.md appends instead.
~/.pi/agent/AGENTS.mduserofficialall
Global user-level instructions.
~/.pi/agent/SYSTEM.mduserofficialall
Global system prompt replacement; APPEND_SYSTEM.md appends instead.

skills

.pi/skills/projectofficialall
~/.pi/agent/skills/userofficialall
Global user-level skills.

commands

.pi/prompts/projectofficialall
Prompt templates invoked as slash commands.
~/.pi/agent/prompts/userofficialall
Global user-level prompt templates.

promptTemplates

.pi/prompts/projectofficialall
Prompt templates invoked as slash commands.
~/.pi/agent/prompts/userofficialall
Global user-level prompt templates.

Empty

hookstempThat is not the same as the feature being missing.

Env overrides

Variables the harness reads to move a root. The path is the default while the variable is unset; resolve() applies a set one to temp.

EnvenvOverrides2 variables

PI_CODING_AGENT_DIR~/.pi/agentconfig · sessions · instructions · skills · commands · promptTemplates
A leading ~ in the value is expanded.
PI_CODING_AGENT_SESSION_DIR~/.pi/agent/sessionssessions
Takes precedence over PI_CODING_AGENT_DIR for sessions; --session-dir beats both.

MCP servers

FilemcpConfigs2 files

~/.pi/agent/mcp.jsonuser · json · pi · mcpServers
.pi/mcp.jsonproject · json · pi · mcpServers

Detection

CalldetectHarness()env, then project

envVars

PI_CODING_AGENT
PI_SESSION_ID
PI_SESSION_FILE

projectMarkers

Persistence

JSON - Settings, auth, trust, models, and keybindings files. (official)
JSONL - Session transcripts. (official)

syncAgentsFiles links ~/.pi/agent/AGENTS.md to the master bundle.

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