Add a new `localModelSavings` config and `codeburn model-savings` CLI
that maps a local-model name (e.g. llama3.1:8b) to a paid baseline
(e.g. gpt-4o). The local call still costs $0; the new `savingsUSD`
field tracks the counterfactual spend avoided by running locally and
is reported separately from `costUSD` everywhere a number is shown.
* Parser normalization (`applyLocalModelSavings`) runs on Claude
parse, direct provider calls, and the cached-call path. It forces
`costUSD` to 0 and attaches `savingsUSD` + `savingsBaselineModel`
+ `isLocalSavings` on the `ParsedApiCall`. Local-savings wins for
actual cost even when the same model is also in `modelAliases`.
* Session, project, day, model, category, activity, skill, and
subagent rollups all carry `savingsUSD` alongside `costUSD`.
* `status --format json` adds `today.savings` and `month.savings`.
* `status --format menubar-json` adds a `current.localModelSavings`
block (totalUSD, calls, byModel, byProvider) plus savings on
topModels, topProjects, topSessions, topActivities, and history
daily entries. Schema fields default-decode for backward compat.
* `report --format json` adds savings across overview/daily/
projects/models/activities/skills/subagents/topSessions, with
the active paid baseline name on each model row.
* `models` command gains a `Saved` column on table/markdown/CSV
and a `savingsUSD`/`savingsBaselineModel` pair in JSON. Default
`--min-cost 0.01` filter now ORs in `savingsUSD >= minCost` so
local models with $0 actual cost but >0 savings still surface.
* CSV/JSON exports add a `Saved (CODE)` column on summary/daily/
models/projects/sessions.
* Dashboard TUI shows a green 'saved $X by local models' footer
line in the overview when any savings are present.
* macOS Swift payload gains a `LocalModelSavings` Codable block
and savings fields on every model/activity/session/daily
struct. Hero shows a green leaf 'Saved $X' caption, models
section gets a green `Saved` column. `swift build` clean.
* GNOME indicator adds 'saved $X' to the hero meta line and a
`codeburn-model-saved` column to the model row.
* Daily cache schema bumped to v8 (`savingsUSD` on day/model/
category/provider). `savingsConfigHash` invalidates the cache
when the user changes their baseline mapping so historical
saved-spend numbers never lie about a stale baseline.
* Defensive `Object.hasOwn` lookup in `getLocalSavingsBaseline`
blocks the prototype-pollution test that previously surfaced via
the savings path with a hostile `__proto__` model name.
* New tests (5 files, 25 tests, 549 lines) cover pricing helpers,
end-to-end parser normalization, day aggregator savings,
menubar payload savings, CLI set/list/remove, and
daily-cache hash invalidation. Existing tests for daily-cache
/ day-aggregator / models-report updated for the new fields.
Full vitest suite: 1028/1028 passing across 73 test files.
`tsc --noEmit` clean. `npm run build` clean.
(Note: `mac/Tests` has a pre-existing `no such module 'Testing'`
environment error on the installed Swift toolchain, confirmed
on `main` before this PR; not caused by these changes.)
