Run a bookkeeping client's fixed-asset depreciation for 2026 with a mid-month convention, straight-line and declining-balance methods, and disposals

# Run a bookkeeping client's fixed-asset depreciation for 2026 with a mid-month convention, straight-line and declining-balance methods, and disposals Inputs: `assets.csv` (asset_id, category, cost, salvage, life_months, method, in_service, disposed_on, proceeds) for a small business client of a bookkeeping firm. All records are synthetic; amounts are in dollars. These rules are the firm's policy; where `controller-note.txt` disagrees, the rules win. Rules: - Mid-month convention: an asset placed in service on day 1-15 of a month starts depreciating that month; on day 16 or later, it starts the next month. An asset disposed of on day 1-15 of a month gets no depreciation for that month; on day 16 or later it gets that month's depreciation, and none after it. - Schedule: depreciation is charged month by month from the asset's first month (which may be before 2026) until life_months monthly charges have been made or the asset is disposed of. Book value = cost − accumulated depreciation. - Straight line (method SL): every monthly charge is (cost − salvage) / life_months, rounded half-up to the cent, except the last month of the life, whose charge is whatever brings accumulated depreciation to exactly cost − salvage. - Double declining (method DDB): a month's charge is the larger of (a) the opening book value × 2 / life_months and (b) (opening book value − salvage) / the number of monthly charges left including this one, each rounded half-up to the cent, but never more than opening book value − salvage. - Disposal: gain_loss = proceeds − (cost − accumulated depreciation at disposal), counting only the depreciation the convention allows. A disposed asset leaves the register: its accum_2026_12_31 and nbv_2026_12_31 are 0, but its 2026 charges still count in dep_2026. - Write `out/fixed-assets.json`: `{"assets": {"<asset_id>": {"dep_2026": <depreciation charged in 2026>, "accum_2026_12_31": <dollars>, "nbv_2026_12_31": <dollars>}, ...}, "disposals": {"<asset_id>": <gain_loss>, ...}, "by_category": {"<category>": <sum of dep_2026>, ...}}`. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.