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Author	SHA1	Message	Date
Tejas Chopra	6ec3e3478a	feat(cli,pricing): add CLI extension seam and prompt-cache TTL pricing (#2802) ... ## Description Two small, independent additions. Both exist because an out-of-tree package needed them and neither had a home in the current API. 1. **`headroom.cli_extension`** — an entry-point group so a package can add a `headroom` subcommand. `headroom.proxy_extension` requires a running FastAPI app, so it cannot carry a read-only CLI tool, and `_register_commands()` was a hardcoded import list with no discovery. 2. **`headroom/pricing/cache_ttl.py`** — the prompt-cache TTL price structure (read `0.10x`, 5m write `1.25x`, 1h write `2.00x` of base input) plus the break-even share above which the 1h TTL is cheaper. `ModelPricing` carries `cached_input_per_1m` for reads but has no field for the *write* side. Closes # ## Type of Change - [ ] Bug fix (non-breaking change that fixes an issue) - [x] New feature (non-breaking change that adds functionality) - [ ] Breaking change (fix or feature that would cause existing functionality to change) - [ ] Documentation update - [ ] Performance improvement - [ ] Code refactoring (no functional changes) ## Changes Made - `headroom/cli/extensions.py` (new) — `register_all(main)` discovers the `headroom.cli_extension` group. Contract: `register(main: click.Group) -> None`. Invoked from `_register_commands()` **last**, so built-ins are already attached. - Deliberately **not** opt-in gated, unlike proxy extensions: installing the package is the opt-in, because adding a subcommand cannot silently change what an existing command does. What *would* be a silent change is shadowing a built-in, so that is detected and rolled back — a stale plugin can never quietly take over `headroom proxy`. Load failures and partial registrations roll back too, and one bad plugin never blocks another. - `headroom/pricing/cache_ttl.py` (new) — `CACHE_READ_MULTIPLIER`, `CACHE_WRITE_MULTIPLIERS`, `cache_write_multiplier()`, `cache_rates_per_1m()`, `ttl_breakeven_share()`. Ratios are derived from base input rather than transcribed into a per-model table that would triple its columns and drift. - `cache_write_multiplier()` raises on an unknown TTL rather than falling back to the cheaper 5m rate, which would understate cost. - `headroom/pricing/litellm_pricing.py` — three additive optional fields on `LiteLLMModelPricing` exposing LiteLLM's own `cache_read_input_token_cost`, `cache_creation_input_token_cost` and `cache_creation_input_token_cost_above_1hr` (present for 212 and 123 models respectively). Published rates should win over derived ones. All default to `None`, and `None` means "not published" — distinct from `0.0` meaning "free" — so every existing caller is unaffected. - `headroom/pricing/__init__.py` — re-exports. ### Why `ttl_breakeven_share()` exists The TTL trade has two terms and both must be counted: moving to 1h turns idle-gap rewrites into cheap reads **and** raises the price of every write that still happens. Modelling only the recovery overstates the saving. On a real 531-transcript corpus that error was **1.9x** — $1,021 claimed against $538 real. `test_write_premium_is_not_forgotten` pins those exact figures so the mistake cannot be reintroduced quietly. ## Testing - [x] Unit tests pass (`pytest`) - [x] Linting passes (`ruff check .`) - [x] Type checking passes (`mypy headroom`) — see note below - [x] New tests added for new functionality - [x] Manual testing performed ### Test Output ```text $ python -m pytest tests/test_cli_extension_seam.py tests/test_pricing_cache_ttl.py tests/test_pricing_from_litellm.py -q tests/test_cli_extension_seam.py ....... [ 25%] tests/test_pricing_cache_ttl.py .......... [ 62%] tests/test_pricing_from_litellm.py .......... [100%] ======================== 27 passed, 1 warning in 3.54s ========================= $ .venv/bin/ruff check headroom/cli/extensions.py headroom/cli/main.py headroom/pricing/ tests/test_cli_extension_seam.py tests/test_pricing_cache_ttl.py All checks passed! $ .venv/bin/mypy --python-version 3.12 headroom/cli/extensions.py headroom/pricing/cache_ttl.py headroom/pricing/litellm_pricing.py Success: no issues found in 3 source files ``` `tests/test_pricing_from_litellm.py` is the **pre-existing** pricing suite, included to show the `LiteLLMModelPricing` change is non-breaking. **mypy note.** With the repo's configured `python_version = "3.10"`, mypy fails on numpy's own stubs for any file that transitively reaches numpy: ```text $ .venv/bin/mypy headroom/pricing/cache_ttl.py .venv/lib/python3.12/site-packages/numpy/__init__.pyi:737: error: Type statement is only supported in Python 3.12 and greater [syntax] Found 1 error in 1 file (errors prevented further checking) ``` This is pre-existing and unrelated — untouched files reproduce it identically (`mypy headroom/cli/doctor.py`, `mypy headroom/pricing/registry.py`). Hence the `--python-version 3.12` run above, which matches the interpreter actually in use. Worth fixing separately; not addressed here. ## Real Behavior Proof - **Environment:** macOS 15 (darwin 25.4.0), Python 3.12.6, `headroom-ai` 0.34.0 working tree, branch off `upstream/main`. - **Exact command / steps:** 1. Built a separate out-of-tree package declaring `[project.entry-points."headroom.cli_extension"] fleet = "headroom_fleet.cli:register"`. 2. `pip install --no-deps headroom_fleet-0.1.0-py3-none-any.whl` 3. `headroom econ --help` - **Observed result:** the subcommand registers with no configuration and appears in `headroom --help`: ```text $ python -c "import importlib.metadata as m; print([e.name+' -> '+e.value for e in m.entry_points(group='headroom.cli_extension')])" ['fleet -> headroom_fleet.cli:register'] $ headroom --help | grep econ econ Report where local AI-coding token spend goes, and what... $ headroom econ --help Usage: headroom econ [OPTIONS] [COMMAND] [ARGS]... Commands: fix Write the recommended cache-TTL and compaction settings. unfix Restore every setting ``econ fix`` changed, exactly as it was. ``` `headroom --help` and every built-in still work with the plugin installed and after it is uninstalled. Verified per-model cache rates resolve from LiteLLM for `claude-opus-4-8`, `claude-opus-5`, `claude-sonnet-5` and `claude-haiku-4-5-20251001` — all exactly `1.250x` / `2.000x` / `0.100x` of base input, matching the derived fallback. - **Not tested:** Windows; a plugin that raises at *import* time rather than in `register()` (covered by unit test with a stubbed entry point, not a real package); the `--python-version 3.10` mypy path, which is blocked by the pre-existing numpy stub issue above. ## Review Readiness - [x] I have performed a self-review - [x] This PR is ready for human review ## Checklist - [x] My code follows the project's style guidelines ## Note for reviewers This PR contains **only** the two additions above. Unrelated `plugins/opencode/src/transport.ts` changes in my working tree are deliberately excluded and will follow separately. 🤖 Generated with [Claude Code](https://claude.com/claude-code)	2026-08-05 12:24:49 -07:00