[Bug]: MCP mssql_connect reuses existing connection instead of creating new one with specified profile credentials

@caohai is already working on this.

Since Mar 12, 2026.

### Description

Extension: MS SQL Server (mssql) for VS Code

Environment:

VS Code (latest)
MSSQL Extension with MCP tools enabled
Windows
Description:

When multiple connection profiles target the same SQL Server instance but use different SQL Login credentials and databases, mssql_connect always reuses the first established connection instead of creating a new one with the requested profile's credentials.

### Steps to Reproduce

Steps to Reproduce:

Create two connection profiles pointing to the same server:

Profile_A: server myserver.example.com,1525, user UserA, database DatabaseA
Profile_B: server myserver.example.com,1525, user UserB, database DatabaseB
Connect using Profile_A (either explicitly or implicitly via a prior session)

Call mssql_connect with:

Run SELECT DB_NAME() AS current_database, SUSER_NAME() AS login_name on the returned connection

Expected Result:

current_database = DatabaseB
login_name = UserB
Actual Result:

current_database = DatabaseA
login_name = UserA
The tool returns success: true and a new connectionId, giving no indication that the wrong profile was used
Additional Notes:

The tool always returns a successful connection with a unique connectionId, giving no indication that the wrong profile was used.
mssql_change_database also fails with "Failed to connect to database: DatabaseB", likely because UserA has no access to DatabaseB.
Cross-database queries (DatabaseB.dbo.table) fail with: "The server principal 'UserA' is not able to access the database 'DatabaseB' under the current security context."
Disconnecting the existing connection and reconnecting with Profile_B still yields the same result — UserA on DatabaseA.
This only happens when both profiles point to the same server. It appears the MCP tool layer is matching/reusing connections by server name, ignoring the different credentials and database.

### Affected Area

- [ ] Connection dialog (SQL Server | Azure browse/Fabric browse)
- [ ] Query editor
- [ ] Query results panel
- [ ] Object Explorer
- [x] GitHub Copilot integration
- [ ] Preview/Edit data
- [ ] Table Designer
- [ ] Schema Designer
- [ ] Schema Compare
- [ ] Local SQL Server Container provisioning
- [ ] SQL database in Fabric provisioning
- [ ] DACPAC/BACPAC export/import
- [ ] SQL Database projects
- [ ] Query Plan Visualizer
- [x] Other (please describe below)

### If you selected "Other", please describe the affected area

Using CoPilot and Opus 4.6

### Environment Information

Version: 1.111.0 (user setup)
Commit: ce099c1ed25d9eb3076c11e4a280f3eb52b4fbeb
Date: 2026-03-06T23:06:10Z
Electron: 39.6.0
ElectronBuildId: 13330601
Chromium: 142.0.7444.265
Node.js: 22.22.0
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.22631
SQL-Server: Microsoft SQL Server 2017 (RTM-CU31-GDR) - 14.0.3515.1 - Standard Edition (64-bit)
Copilot: 0.39 (2026-03-09)

### Confirmation

- [x] I have searched existing issues and couldn't find a match
- [x] I want to work on this issue