fix(editor): keep query results when switching between connections

[iamthenuggetman]

Summary

Closes #292

With two connections open, switching to another connection and back wiped the first connection's query results: the tab kept its SQL, but the result grid came back empty.

Root cause (as suspected in the issue): the tab-loading effect in EditorProvider re-runs on every activeConnectionId change and replaces the connection's live tabs with the storage copies — and tabs are persisted result-stripped (cleanTabForStorage removes result, error, executionTime, etc.). So switching back to an already-loaded connection clobbered live tabs holding results with result-less storage copies.

Fix

Skip the storage reload when the connection's tabs are already live in memory (EditorProvider.tsx). During a session the in-memory tab state is the source of truth — the continuous save effect (tabs/activeTabIds change → saveTabsToStorage) already keeps storage in sync for the next app start, so nothing is lost by not reloading.

This implements the issue's first suggested approach (guard on existing tabs). The merge-instead-of-reload alternative was unnecessary: the only reason to read storage is to restore tabs that aren't in memory, which by definition only happens on the first visit to a connection.

Side benefit: switching back to a loaded connection no longer flashes the loading state or re-runs the storage round-trip at all.

What doesn't change

• First visit to a connection (including app start) still loads tabs from storage, including the legacy notebook-tab migration.
• Closing all of a connection's tabs and revisiting still loads from storage (in-memory guard finds no tabs) and creates the initial tab.
• Cross-connection notebook open (pendingNotebookRef) is unaffected: with the target connection already loaded, the deferred open resolves immediately instead of waiting out a redundant load.

Test plan

• New regression test in tests/contexts/EditorProvider.test.tsx simulating the issue's exact repro: load conn-1's tab from storage → set a live result → switch to conn-2 (initial tab created) → switch back. Asserts the tab keeps its query and its result, and that load_editor_preferences ran only once for conn-1. Verified it fails without the fix and passes with it.
• pnpm vitest run: full suite passes (3431 tests)
• tsc -b: clean
• eslint on changed source: clean
• Manually verified with the demo/ Docker stack (MySQL + PostgreSQL connections): results survive switching away and back; tabs still restore correctly from storage after an app restart.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• src/contexts/EditorProvider.tsx
• tests/contexts/EditorProvider.test.tsx

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_{Reviewed by ling-3.0-flash-free · Input: 72.5K · Output: 8.8K · Cached: 486K}