Add pi.dev agent skill support

README.md

@@ -3,8 +3,8 @@
 Let your AI coding agent talk to other AI coding agents.
 
 x-agent is a set of [agentskills.io](https://agentskills.io) skills that enable any AI CLI tool — Codex, Cursor, Claude
-Code, Gemini CLI, Junie, Qwen Code, OpenCode — to delegate tasks to or get second opinions from the others. Install it once, and your agent
-gains the ability to call any of the other six.
+Code, Gemini CLI, Junie, Qwen Code, OpenCode, Pi — to delegate tasks to or get second opinions from the others. Install it once, and your agent
+gains the ability to call any of the other seven.
 
 ## Why
 
@@ -42,6 +42,7 @@ adds a round-trip to another CLI, so use it when the extra signal is worth the t
 | Junie          | `junie`       | Junie default        | LLM-agnostic, BYOK support                               |
 | Qwen Code      | `qwen`        | Qwen default         | Qwen model family, `--yolo` for auto-approve             |
 | OpenCode       | `opencode`    | OpenCode default     | Multi-provider, uses `run` subcommand with auto-approval |
+| Pi             | `pi`          | `sonnet`             | Multi-provider, minimal terminal coding harness          |
 
 ## How to use it
 
@@ -117,7 +118,7 @@ git clone https://github.com/darshitpp/x-agent.git .claude/skills/x-agent
 ```
 
 After installation, the skills appear automatically in Claude Code's available skills list. Each CLI has its own skill (
-`codex`, `cursor`, `claude`, `gemini`, `junie`, `qwen`, `opencode`) that triggers based on context.
+`codex`, `cursor`, `claude`, `gemini`, `junie`, `qwen`, `opencode`, `pi`) that triggers based on context.
 
 To update later:
 
@@ -142,6 +143,7 @@ x-agent/
 ├── junie/SKILL.md                    # Thin entry point (~27 lines)
 ├── qwen/SKILL.md                     # Thin entry point (~27 lines)
 ├── opencode/SKILL.md                # Thin entry point (~27 lines)
+├── pi/SKILL.md                      # Thin entry point (~20 lines)
 ├── references/
 │   ├── shared-procedure.md           # Core procedure (~105 lines)
 │   ├── cli-codex.md                  # Codex CLI identity, invocation, version matrix
@@ -150,7 +152,8 @@ x-agent/
 │   ├── cli-gemini.md                 # Gemini CLI identity, invocation, version matrix
 │   ├── cli-junie.md                  # Junie CLI identity, invocation, version matrix
 │   ├── cli-qwen.md                   # Qwen Code CLI identity, invocation, version matrix
-│   └── cli-opencode.md              # OpenCode CLI identity, invocation, version matrix
+│   ├── cli-opencode.md              # OpenCode CLI identity, invocation, version matrix
+│   └── cli-pi.md                    # Pi CLI identity, invocation, version matrix
 ├── scripts/
 │   ├── validate-metadata.py          # Validates SKILL.md frontmatter (authoring + CI)
 │   ├── query-cli.sh                  # Maintainer-only CLI wrapper (not used by skills at runtime)
@@ -241,7 +244,7 @@ a `SKILL.md` entry point.
 | Project                 | `.claude/skills/x-agent/`   |
 
 **Invoke:** Ask naturally ("get a second opinion from Cursor") or explicitly with `/codex`, `/cursor`, `/claude`,
-`/gemini`, `/junie`, `/qwen`, `/opencode`. Claude loads the skill automatically when relevant.
+`/gemini`, `/junie`, `/qwen`, `/opencode`, `/pi`. Claude loads the skill automatically when relevant.
 
 [Claude Code skills docs](https://code.claude.com/docs/en/skills)
 

assets/result-template.md

@@ -39,4 +39,4 @@
 
 <Brief commentary only if output needs clarification. Otherwise omit this section.>
 
-<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

claude/assets/result-template.md

@@ -39,4 +39,4 @@
 
 <Brief commentary only if output needs clarification. Otherwise omit this section.>
 
-<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

claude/references/shared-procedure.md

@@ -120,4 +120,4 @@ Delegation mode uses lighter context — task description and relevant file path
 | Version not in matrix          | Use latest known version's flags, warn user                             |
 | Host model family undetectable | Prefer models from a different provider than target CLI's default       |
 | CLI execution timeout (>120s)  | Kill process, report timeout, suggest simpler prompt or different model |
-| Unrecognized model name        | Classify as Balanced, proceed normally                                  |
+| Unrecognized model name        | Classify as Balanced, proceed normally                                  |

codex/assets/result-template.md

@@ -39,4 +39,4 @@
 
 <Brief commentary only if output needs clarification. Otherwise omit this section.>
 
-<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

codex/references/shared-procedure.md

@@ -120,4 +120,4 @@ Delegation mode uses lighter context — task description and relevant file path
 | Version not in matrix          | Use latest known version's flags, warn user                             |
 | Host model family undetectable | Prefer models from a different provider than target CLI's default       |
 | CLI execution timeout (>120s)  | Kill process, report timeout, suggest simpler prompt or different model |
-| Unrecognized model name        | Classify as Balanced, proceed normally                                  |
+| Unrecognized model name        | Classify as Balanced, proceed normally                                  |

cursor/assets/result-template.md

@@ -39,4 +39,4 @@
 
 <Brief commentary only if output needs clarification. Otherwise omit this section.>
 
-<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

cursor/references/shared-procedure.md

@@ -120,4 +120,4 @@ Delegation mode uses lighter context — task description and relevant file path
 | Version not in matrix          | Use latest known version's flags, warn user                             |
 | Host model family undetectable | Prefer models from a different provider than target CLI's default       |
 | CLI execution timeout (>120s)  | Kill process, report timeout, suggest simpler prompt or different model |
-| Unrecognized model name        | Classify as Balanced, proceed normally                                  |
+| Unrecognized model name        | Classify as Balanced, proceed normally                                  |

gemini/assets/result-template.md

@@ -39,4 +39,4 @@
 
 <Brief commentary only if output needs clarification. Otherwise omit this section.>
 
-<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

gemini/references/shared-procedure.md

@@ -120,4 +120,4 @@ Delegation mode uses lighter context — task description and relevant file path
 | Version not in matrix          | Use latest known version's flags, warn user                             |
 | Host model family undetectable | Prefer models from a different provider than target CLI's default       |
 | CLI execution timeout (>120s)  | Kill process, report timeout, suggest simpler prompt or different model |
-| Unrecognized model name        | Classify as Balanced, proceed normally                                  |
+| Unrecognized model name        | Classify as Balanced, proceed normally                                  |

junie/assets/result-template.md

@@ -39,4 +39,4 @@
 
 <Brief commentary only if output needs clarification. Otherwise omit this section.>
 
-<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

junie/references/shared-procedure.md

@@ -120,4 +120,4 @@ Delegation mode uses lighter context — task description and relevant file path
 | Version not in matrix          | Use latest known version's flags, warn user                             |
 | Host model family undetectable | Prefer models from a different provider than target CLI's default       |
 | CLI execution timeout (>120s)  | Kill process, report timeout, suggest simpler prompt or different model |
-| Unrecognized model name        | Classify as Balanced, proceed normally                                  |
+| Unrecognized model name        | Classify as Balanced, proceed normally                                  |

opencode/assets/result-template.md

@@ -39,4 +39,4 @@
 
 <Brief commentary only if output needs clarification. Otherwise omit this section.>
 
-<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

opencode/references/shared-procedure.md

@@ -120,4 +120,4 @@ Delegation mode uses lighter context — task description and relevant file path
 | Version not in matrix          | Use latest known version's flags, warn user                             |
 | Host model family undetectable | Prefer models from a different provider than target CLI's default       |
 | CLI execution timeout (>120s)  | Kill process, report timeout, suggest simpler prompt or different model |
-| Unrecognized model name        | Classify as Balanced, proceed normally                                  |
+| Unrecognized model name        | Classify as Balanced, proceed normally                                  |

pi/SKILL.md

@@ -0,0 +1,20 @@
+---
+name: pi
+description: Delegate tasks or get a second opinion from Pi CLI. Infers mode (delegation vs validation) from prompt context. Detects available models at runtime via the CLI. Use when cross-validating code, plans, or architecture with Pi, or offloading work to it. Do not use when already running inside Pi CLI or for tasks that do not benefit from cross-model input.
+---
+
+# Cross-Agent Task Runner — Pi CLI
+
+## Procedures
+
+**Step 1: Self-Call Detection**
+
+1. Check for `PI_AGENT` environment variable or `pi` in process ancestry.
+2. If detected, stop and inform the user:
+   "Cannot invoke Pi from within Pi. Use a different target CLI."
+
+**Step 2: Execute Shared Procedure**
+
+1. Read `references/shared-procedure.md` for the core workflow (mode inference, context gathering, prompt construction, result presentation).
+2. Read `references/cli-pi.md` for Pi-specific flags, model selection heuristics, and version compatibility matrix.
+3. Follow the shared procedure using the Pi-specific details.

pi/assets/result-template.md

@@ -0,0 +1,42 @@
+<!-- VALIDATION MODE TEMPLATE -->
+
+## Cross-Model Validation
+
+**Target CLI:** `<cli-name>`
+**Model:** `<model-id>` (<selection-reason>)
+**Review type:** `<plan|code|architecture|general>`
+**Mode:** validation
+
+### Second Opinion
+
+<Target model's key findings. Quote directly where precise.>
+
+### Agreement
+
+<Points where host agent agrees, with reasoning.>
+
+### Counterpoints
+
+<Points where host agent disagrees or finds low-signal. Explain reasoning.>
+
+### Synthesis
+
+<Recommended action based on both perspectives.>
+
+<!-- DELEGATION MODE TEMPLATE -->
+
+## Delegated Task Result
+
+**Target CLI:** `<cli-name>`
+**Model:** `<model-id>` (<selection-reason>)
+**Mode:** delegation
+
+### Result
+
+<Target CLI's output, presented directly.>
+
+### Notes
+
+<Brief commentary only if output needs clarification. Otherwise omit this section.>
+
+<!-- Note: Templates use ## (h2) headers. Adjust header depth to fit the host agent's current output context. -->

pi/references/cli-pi.md

@@ -0,0 +1,31 @@
+# Pi CLI Reference
+
+## 1. CLI Identity & Invocation
+
+- **Command:** `pi`
+- **Non-interactive flag:** `-p` / `--print`
+- **Output format flag:** `--output-format text|json|stream-json`
+- **Trust/auto-approve flag:** `--dangerously-skip-permissions`
+- **List models command:** `pi --list-models 2>&1` (if available) or infer from `pi --help`
+- **Self-call detection:** Check for `PI_AGENT` environment variable or `pi` in process ancestry
+
+## 2. Model Selection Heuristic
+
+- **Default model (fallback):** `sonnet` (alias for claude-sonnet-4-6)
+- **Aliases:** `opus` → claude-opus-4-6, `sonnet` → claude-sonnet-4-6, `haiku` → claude-haiku-4-5
+- **Quirks:** Model can also be set via `ANTHROPIC_MODEL` env var. Supports `--fallback-model` for overload scenarios.
+
+## 3. Invocation Template
+
+| Mode           | Command                                                                |
+|----------------|------------------------------------------------------------------------|
+| **Validation** | `cat "$PROMPT_FILE" \| pi -p --model <model> --output-format text` |
+| **Delegation** | `cat "$PROMPT_FILE" \| pi -p --model <model> --output-format text` |
+
+Note: Pi validation and delegation use the same invocation — no separate trust flag needed for print mode.
+
+## 4. Version Compatibility Matrix
+
+| Version | Print Flag       | Model Flag | Output Format                             | Notes   |
+|---------|------------------|------------|-------------------------------------------|---------|
+| 2.1.x   | `-p` / `--print` | `--model`  | `--output-format text\|json\|stream-json` | Current |