Skip to content

Launch Flag Injection — Reference

When amplihack starts claude, copilot, codex, or amplifier, it builds the subprocess command line by combining flags it injects automatically with any extra arguments the user supplied. This document describes every flag that amplihack injects, the conditions under which each is injected, and how users can override the defaults.

Contents

Injected flags overview

Flag Injected when? Applicable tools Override mechanism
--dangerously-skip-permissions --skip-permissions passed AND tool is Claude-compatible claude, rusty, rustyclawd, amplifier omit --skip-permissions
--model <value> user did not pass --model AND tool is Claude-compatible claude, rusty, rustyclawd, amplifier AMPLIHACK_DEFAULT_MODEL or --model on the command line
--resume only when amplihack launch --resume launch only (not claude) pass --resume to the launch subcommand
--continue only when amplihack launch --continue launch only (not claude) pass --continue to the launch subcommand

--dangerously-skip-permissions

amplihack passes --dangerously-skip-permissions to the tool subprocess only when both conditions are met:

  1. The user passed --skip-permissions on the amplihack command line.
  2. The target tool is Claude-compatible (claude, rusty, rustyclawd, or amplifier).

Tools that are not Claude-compatible (copilot, codex) never receive this flag because they do not support it.

# User explicitly opts in:
amplihack launch --skip-permissions

# amplihack spawns:
claude --dangerously-skip-permissions --model opus[1m]

# Without --skip-permissions, the flag is NOT injected:
amplihack claude

# amplihack spawns:
claude --model opus[1m]

# Non-Claude tools never receive it, even with --skip-permissions:
amplihack copilot --skip-permissions

# amplihack spawns:
copilot <extra_args...>

Rationale: The --dangerously-skip-permissions flag bypasses Claude's interactive confirmation prompts. It is gated behind an explicit opt-in (--skip-permissions) so that users in trusted automated environments can suppress the prompt, while interactive sessions retain the safety check.

Python launcher note: The Python launcher in amplihack/launcher/core.py may behave differently. Verify Python launcher behavior independently.

--model

amplihack injects --model <value> into the subprocess command line to set the AI model variant used for the session. This flag is only injected for Claude-compatible tools (claude, rusty, rustyclawd, amplifier). Non-Claude tools (copilot, codex) use their own default model selection.

Default model

The default model is opus[1m]. It is used when:

  • The user has not passed --model on the command line, and
  • AMPLIHACK_DEFAULT_MODEL is not set in the environment.
# User runs:
amplihack claude

# amplihack spawns:
claude --model opus[1m]

Override via environment variable

Set AMPLIHACK_DEFAULT_MODEL to use a different model for all sessions without changing the command line:

export AMPLIHACK_DEFAULT_MODEL=sonnet
amplihack claude

# amplihack spawns:
claude --model sonnet

This is the recommended approach for teams or CI environments that standardise on a particular model.

# .github/workflows/ai-tasks.yml
env:
  AMPLIHACK_DEFAULT_MODEL: "sonnet"
  AMPLIHACK_NONINTERACTIVE: "1"

steps:
  - run: amplihack claude --print 'Run the lint checks'
    # spawns: claude --model sonnet --print 'Run the lint checks'

Override via command-line flag

Pass --model directly to suppress injection entirely. The user-supplied value is forwarded unchanged and AMPLIHACK_DEFAULT_MODEL is ignored:

amplihack claude --model haiku

# amplihack spawns:
claude --model haiku

Detection is substring-based: if any element of the extra args list equals --model, the injection step is skipped. Partial matches (e.g. --model-config) are not treated as model overrides.

Supported model identifiers

amplihack does not validate the model string — any value is forwarded as-is to the tool. Refer to the tool's own documentation for supported model names. Examples that work at time of writing:

Value Resolves to
opus[1m] Claude claude-opus-4-5 with 1M-token context
sonnet Claude claude-sonnet-4-5
haiku Claude claude-haiku-3-5

--resume and --continue

These flags are passed through only when the user explicitly requests them on the launch subcommand. They are never injected automatically.

Important: The claude subcommand does not support --resume or --continue. Only launch exposes these flags.

amplihack launch --resume --skip-permissions
# spawns: claude --dangerously-skip-permissions --model opus[1m] --resume

amplihack launch --continue --skip-permissions
# spawns: claude --dangerously-skip-permissions --model opus[1m] --continue

The claude, copilot, codex, and amplifier subcommands do not support --resume or --continue.

Extra args passthrough

All positional arguments and flags after the subcommand name are forwarded verbatim to the tool subprocess after the injected flags. Order is:

<binary> [--dangerously-skip-permissions] [--model <value>] [--resume|--continue] <extra_args...>

amplihack claude --print 'Fix the failing tests' --output-format json

# amplihack spawns:
claude --model opus[1m] --print 'Fix the failing tests' --output-format json

There is no processing or escaping of extra_args. What the user types is what the subprocess receives.

Complete command-line assembly

build_command() in crates/amplihack-cli/src/commands/launch.rs assembles the final command line. The assembly order is:

  1. Binary path (resolved by bootstrap::ensure_tool_available())
  2. --dangerously-skip-permissions — only if skip_permissions == true and the tool is Claude-compatible (claude, rusty, rustyclawd, amplifier)
  3. --model <value> — only if --model not already present in extra_args and the tool is Claude-compatible
  4. --resume (if requested — launch subcommand only)
  5. --continue (if requested — launch subcommand only)
  6. All extra_args in the order they were passed on the command line

The following examples show the full assembled command for each launch subcommand with no extra args:

amplihack claude
# → claude --model opus[1m]

amplihack claude --skip-permissions
# → claude --dangerously-skip-permissions --model opus[1m]

amplihack copilot
# → copilot

amplihack codex
# → codex

amplihack amplifier
# → amplifier --model opus[1m]

amplihack launch --skip-permissions
# → claude --dangerously-skip-permissions --model opus[1m]

Python launcher parity

The Rust launcher's injection behaviour is designed to match the Python launcher in amplihack/launcher/core.py. The following table documents the parity contract:

Behaviour Python launcher Rust launcher
--dangerously-skip-permissions always injected conditional: Claude-compatible tool AND --skip-permissions
--model <default> opus[1m] unless AMPLIHACK_DEFAULT_MODEL set same, Claude-compatible tools only
--model suppressed when user provides it yes yes
--resume passthrough yes launch subcommand only
--continue passthrough yes launch subcommand only
extra_args forwarded verbatim yes yes

Intentional divergences (not bugs) are documented in Parity Test Scenarios.