fix(integrations): drop invalid --model/--output-format flags from Forge dispatch

[chelsealong]

Summary

ForgeIntegration never overrode build_exec_args(), so it inherited the generic MarkdownIntegration implementation, which appends --model <model> and --output-format json. Neither flag exists in the Forge CLI (forge only accepts -p/--prompt, --conversation, --directory, --sandbox, --verbose, --agent, --event), so every workflow command:/prompt: step dispatched to Forge failed immediately at argument parsing with exit code 2.

Fixes #4666.

This overrides build_exec_args() in ForgeIntegration (src/specify_cli/integrations/forge/__init__.py) to emit forge -p <prompt> only, applying the SPECKIT_INTEGRATION_FORGE_EXTRA_ARGS operator override before -p (Forge's global flags parse before the prompt flag, matching the existing opencode/goose/codex/cursor-agent ordering). model is intentionally dropped rather than remapped onto --agent, since --agent selects an agent ID, not a model — model selection in Forge is a persisted setting (forge config set model). Same fix shape as the existing overrides for Amp (#4581), opencode (#2409) and goose (#3781).

Test plan

Added TestForgeExecArgs to tests/integrations/test_integration_forge.py covering:

• only -p <prompt> is emitted (no --model/--output-format)
• output_json=True does not append --output-format
• model=... does not append --model or --agent
• SPECKIT_INTEGRATION_FORGE_EXTRA_ARGS is applied before -p

Verified the new tests fail without the fix (via git checkout HEAD -- src/specify_cli/integrations/forge/__init__.py to restore the inherited MarkdownIntegration.build_exec_args, confirming exit code 2 shape):

$ uv run pytest tests/integrations/test_integration_forge.py -k TestForgeExecArgs -q
...
FAILED ...test_build_exec_args_omits_output_format_flag
FAILED ...test_build_exec_args_omits_model_flag
FAILED ...test_build_exec_args_applies_extra_args_before_prompt
3 failed, 1 passed, 26 deselected in 0.11s

With the fix restored:

$ uv run pytest tests/integrations/test_integration_forge.py -q
============================== 30 passed in 0.63s ==============================

$ uv run pytest -q
========== 8364 passed, 12 skipped, 53 warnings in 404.47s (0:06:44) ===========

$ uvx ruff@0.15.0 check src/specify_cli/integrations/forge/__init__.py tests/integrations/test_integration_forge.py
All checks passed!

• Added/updated tests, confirmed to fail without the fix
• Full test suite passes
• ruff check passes

AI disclosure

This change was authored by an AI coding agent (Claude Code).

🤖 Generated with Claude Code