fix(drivers): avoid mutating caller input options in fs-lite and db0

[LeSingh1]

Problem

Fixes #566

Two drivers were mutating the caller's input options object, which can cause unexpected side-effects when the same options object is reused or inspected after driver creation.

fs-lite driver

// Before — mutates caller's opts
opts.base = resolve(opts.base);

The fs-lite driver overwrote opts.base with resolve(opts.base), modifying the original object passed in by the caller.

db0 driver

// Before — mutates caller's opts
opts.tableName = opts.tableName || DEFAULT_TABLE_NAME;

The db0 driver wrote a default value back into opts.tableName, modifying the original object passed in by the caller.

Fix

In both cases, the mutation is replaced with a local const that holds the resolved/defaulted value, leaving the caller's object untouched:

// fs-lite — after
const base = resolve(opts.base);

// db0 — after
const tableName = opts.tableName || DEFAULT_TABLE_NAME;

For db0, tableName is also passed as an explicit argument to setupTable() instead of reading it from the options object inside that function.

Note: the fs.ts driver already handles this correctly by using const base = resolve(userOptions.base) without touching userOptions.

Changes

• src/drivers/fs-lite.ts: replace opts.base = resolve(opts.base) with const base = resolve(opts.base) and update all usages
• src/drivers/db0.ts: replace opts.tableName = opts.tableName || DEFAULT_TABLE_NAME with const tableName = ... and thread it through to setupTable()

Summary by CodeRabbit

• Bug Fixes

  • Improved driver configuration handling so supplied options remain unchanged.
  • Improved consistency when resolving database tables and filesystem paths.
  • Ensured default table and path settings are applied reliably across supported drivers.

• Reliability

  • Added safeguards and regression coverage to preserve application configuration during driver setup.
  • Improved consistency across database, filesystem, and PlanetScale storage operations.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 250de1dc-7e3c-48a2-9187-024788d9dcfb

📥 Commits

Reviewing files that changed from the base of the PR and between 8de7325 and 3364e49.

📒 Files selected for processing (2)

• src/drivers/db0.ts
• src/drivers/planetscale.ts

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 66247540-b3ce-456d-8e40-f735a23d6cca

📥 Commits

Reviewing files that changed from the base of the PR and between 01e1de9 and 8de7325.

📒 Files selected for processing (6)

• src/drivers/db0.ts
• src/drivers/fs-lite.ts
• src/drivers/planetscale.ts
• test/drivers/db0.test.ts
• test/drivers/fs-lite.test.ts
• test/drivers/planetscale.test.ts

🚧 Files skipped from review as they are similar to previous changes (6)

• test/drivers/fs-lite.test.ts
• test/drivers/db0.test.ts
• src/drivers/fs-lite.ts
• test/drivers/planetscale.test.ts
• src/drivers/planetscale.ts
• src/drivers/db0.ts

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📝 Walkthrough

Walkthrough

The db0, fs-lite, and PlanetScale drivers now resolve configuration values locally instead of mutating input options. db0 passes resolved database and table values to table setup. Regression tests verify option preservation.

Changes

Opts mutation removal

Layer / File(s)	Summary
db0 local table configuration src/drivers/db0.ts, test/drivers/db0.test.ts	Resolves tableName locally, passes database and table name to setupTable, and uses the resolved values across SQL operations and dialect-specific table creation. The test verifies that driver creation does not mutate input options.
fs-lite local base path src/drivers/fs-lite.ts, test/drivers/fs-lite.test.ts	Resolves opts.base locally for path construction and returns copied options with the resolved base path. The test verifies that driver creation preserves input options.
PlanetScale local table configuration src/drivers/planetscale.ts, test/drivers/planetscale.test.ts	Resolves the configured or default table locally and uses it across CRUD, metadata, key listing, and clearing queries. The test verifies that driver creation does not mutate input options.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 8de73

This localized change prevents two drivers from mutating caller-provided options without indicating a new user or production impact; no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: pi0

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: preventing caller input option mutation in the fs-lite and db0 drivers.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

⚔️ Resolve merge conflicts 💡

• Resolve merge conflict in branch fix/drivers-mutate-input-options

🧪 Generate unit tests (beta)

• Create PR with unit tests

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