Simpl-Resultat/tasks/lessons.md

Lessons Learned

2026-02-10 - NSIS / Tauri productName

Mistake: Used apostrophe in productName (Simpl'Résultat) which broke the NSIS installer script on Windows CI Pattern: NSIS uses single quotes as string delimiters — special characters in productName get interpolated into NSIS scripts and can break the build Rule: Keep productName in tauri.conf.json free of apostrophes and other shell/script-special characters. Use app.windows[].title for the display name with special characters. Applied: Tauri v2 Windows builds, any NSIS-based packaging

2026-02-10 - GitHub Actions GITHUB_TOKEN permissions

Mistake: Workflow failed with Resource not accessible by integration when tauri-action tried to create a GitHub Release Pattern: By default, GITHUB_TOKEN has read-only contents permission in newer repos / org settings. Creating releases requires write access. Rule: Always add permissions: contents: write at the top level of any GitHub Actions workflow that creates releases or pushes tags/artifacts. Applied: Any workflow using tauri-apps/tauri-action, softprops/action-gh-release, or direct GitHub Release API calls

2026-02-11 - Write tool requires Read first

Mistake: Tried to overwrite the plan file with the Write tool without reading it first, causing an error: "File has not been read yet. Read it first before writing to it." Pattern: The Write tool enforces a safety check — you must Read a file at least once in the conversation before you can Write to it. This prevents accidental overwrites of files you haven't seen. Rule: Always Read a file before using Write on it, even if you intend to completely replace its contents. This applies to plan files, config files, and any existing file. Applied: All file editing workflows, especially plan mode where you repeatedly update the plan file

2026-02-11 - CSV preprocessing must be applied everywhere

Mistake: preprocessQuotedCSV() was only called in parsePreview, not in loadHeadersWithConfig. Desjardins CSVs parsed as single-column in header loading. Pattern: When a preprocessing step is needed for data parsing, it must be applied at EVERY code path that parses the same data — not just the main one. Rule: When adding a preprocessing step, grep for all call sites that parse the same data format and apply the step consistently. Applied: CSV import, any file format with a normalization/preprocessing layer

2026-02-11 - Synthetic headers needed for no-header CSVs in all dispatches

Mistake: parsePreview left headers = [] when hasHeader: false, overwriting previously loaded synthetic headers. Column mapping editor disappeared on back-navigation. Pattern: State dispatches can overwrite previous state. If a component depends on state set by an earlier step, later dispatches must preserve or regenerate that state. Rule: When dispatching state updates that include derived data (like headers), always populate ALL fields — don't leave arrays empty assuming they'll persist from a previous dispatch. Applied: Wizard-style multi-step UIs with back-navigation

2026-02-11 - Constant numeric columns are identifiers, not amounts

Mistake: Account number and transit number columns passed numeric detection because they contain valid numbers, but they're identifiers not amounts. Pattern: Identifier columns have very low cardinality relative to row count (often a single repeated value). Amount columns vary per transaction. Rule: When detecting "amount" columns in CSV auto-detect, exclude numeric columns with ≤1 distinct value. Also treat 0 as "empty" in sparse-complementary detection for debit/credit pairs. Applied: CSV auto-detection, any heuristic column type inference

2026-02-12 - Config fields must be persisted to DB, not hardcoded on restore

Mistake: hasHeader was part of the SourceConfig in-memory object but was never stored in the import_sources DB table. When restoring config from DB, it was hardcoded to true, causing the first data row of headerless CSVs (Desjardins) to be treated as column headers. Pattern: When adding a config field to an in-memory interface, you must also add the column to the DB schema and update all CRUD paths (create, update, restore). Hardcoding a default on restore silently loses user preferences. Rule: For every field in a config interface: (1) verify it has a corresponding DB column, (2) verify it's included in INSERT/UPDATE queries, (3) verify it's restored from the DB row — never hardcoded. Use a grep for the field name across service, hook, and schema files. Applied: Import source config, any settings/preferences that need to survive across sessions