fix(tools): restore tool reachability status during gateway refresh

[bogdanmariusc10]

🔗 Related Issue

Closes #4454
Jira Issue: https://jsw.ibm.com/browse/ICACF-32

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📝 Summary

This PR fixes a critical bug where tools from registered gateways were appearing as offline even though the gateways were functional and successfully returning tools during health checks and refresh operations.

Problem: Tools have a reachable boolean field that tracks their availability. When tools were updated during gateway refresh operations (health checks, manual refresh, OAuth flows), the reachable field was never updated. This meant that if a tool was previously marked as reachable=False during a gateway failure, it would remain offline indefinitely, even after the gateway recovered and successfully returned the tool.

Solution: Modified gateway_service.py to ensure tools are marked as reachable when successfully fetched:

1. _create_db_tool(): Explicitly set enabled=True and reachable=True for newly created tools
2. _update_or_create_tools(): Added logic to mark existing tools as reachable=True when successfully fetched from gateway during refresh operations

Impact: Tools are now automatically restored to online status when gateways successfully return them, resolving the issue where users couldn't invoke tools despite having functional gateway connections.

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🏷️ Type of Change

• Bug fix
• Feature / Enhancement
• Documentation
• Refactor
• Chore (deps, CI, tooling)
• Other (describe below)

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🧪 Verification

Check	Command	Status
Lint suite	make lint	✅ Pass
Unit tests	make test	✅ Pass
Coverage ≥ 80%	make coverage	✅ Pass

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✅ Checklist

• Code formatted (make black isort pre-commit)
• Tests added/updated for changes (existing tests validate the fix)
• Documentation updated (if applicable)
• No secrets or credentials committed

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📓 Notes

Root Cause Analysis

The issue was in the _update_or_create_tools() method. When tools were updated during gateway refresh/health checks:

1. New tools were created via _create_db_tool() which didn't explicitly set reachable=True (relied on model default)
2. Existing tools were updated at lines 4696-4713, but the reachable field was never updated
3. If a tool was previously marked as reachable=False (e.g., during a gateway failure), it stayed offline even after successful gateway health checks and tool refreshes

The gateway's reachable status was correctly updated during health checks (gateway_service.py:3827), but the individual tools' reachable status was not propagated.

Code Changes

File: mcpgateway/services/gateway_service.py

Change 1 - New tool creation (lines 4584-4615):

return DbTool(
    # ... existing fields ...
    # Status fields - tools successfully fetched from gateway are reachable
    enabled=True,
    reachable=True,
    # ... rest of fields ...
)

Change 2 - Existing tool update (lines 4697-4700):

# Always mark tool as reachable when successfully fetched from gateway
if not existing_tool.reachable:
    existing_tool.reachable = True
    fields_to_update = True

User Impact

Before: Users reported tools showing as offline in the UI and receiving errors like:

ERROR: Tool 'github-com-read-tools-search-repositories' exists but is currently offline. 
Please verify if it is running.

After: Tools are automatically restored to online status when gateways successfully return them during any refresh operation (health checks, manual refresh, OAuth flows).