feat(import): harden untrusted spreadsheet boundaries

2026-03-30 08:02:52 +02:00
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+# Import Hardening
+
+**Date:** 2026-03-30
+**Purpose:** Define the safe parser boundary for untrusted spreadsheet imports.
+
+## Decision
+
+- Untrusted workbook imports no longer accept legacy `.xls`.
+- Server-side dispo imports accept only `.xlsx` files.
+- Browser-side ad hoc imports accept `.xlsx` and `.csv`.
+- Trusted export generation may still use `xlsx` until the export paths are migrated separately.
+
+## Server Boundary
+
+The dispo-import reader in [read-workbook.ts](/home/hartmut/Documents/Copilot/capakraken/packages/application/src/use-cases/dispo-import/read-workbook.ts) now enforces:
+
+- normalized filesystem paths before reading
+- regular-file checks
+- non-empty file checks
+- a hard size limit of `15 MiB`
+- `.xlsx`-only parsing behind a hardened server-side parser boundary
+
+The API entry points in [dispo.ts](/home/hartmut/Documents/Copilot/capakraken/packages/api/src/router/dispo.ts) reject non-`.xlsx` workbook paths before staging or validation begins.
+
+## Browser Boundary
+
+The browser import helpers in [excel.ts](/home/hartmut/Documents/Copilot/capakraken/apps/web/src/lib/excel.ts) and [skillMatrixParser.ts](/home/hartmut/Documents/Copilot/capakraken/apps/web/src/lib/skillMatrixParser.ts) now enforce:
+
+- a hard client-side file size limit of `10 MiB`
+- explicit rejection of legacy `.xls`
+- `.xlsx` parsing through `exceljs`
+- `.csv` parsing through a local parser for simple tabular imports
+
+Affected upload flows:
+
+- resource CSV/XLSX import
+- estimate scope spreadsheet import
+- single skill-matrix import
+- batch skill-matrix import
+
+## Rationale
+
+- `.xls` support keeps the old binary workbook format in the untrusted path without enough payoff.
+- the server path keeps compatibility-first `.xlsx` parsing for the current dispo workbooks, but only behind explicit file validation and limits
+- the browser path moves away from blanket `xlsx` import usage to a narrower parser boundary
+- CSV remains useful for lightweight business imports and is small enough to parse with a narrow local parser.