Release MCP inspector sub-contexts promptly after each operation

[Copilot]

connectStdioMCPServer and connectHTTPMCPServer created WithTimeout sub-contexts for each sequential MCP operation (ListTools, ListResources) but cancelled them via defer, holding timer resources until function return rather than releasing them immediately after each operation completed.

Changes

• connectStdioMCPServer and connectHTTPMCPServer: replaced defer cancel() with an immediate cancel() after each sequential MCP operation

// Before — timer held until function return
listToolsCtx, cancel := context.WithTimeout(ctx, MCPOperationTimeout)
defer cancel()
toolsResult, err := session.ListTools(listToolsCtx, ...)

// After — timer released as soon as operation completes
listToolsCtx, cancel := context.WithTimeout(ctx, MCPOperationTimeout)
toolsResult, err := session.ListTools(listToolsCtx, ...)
cancel()

The connectCtx used for client.Connect() retains defer cancel() since it isn't sequential and doesn't benefit from early release.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[plan] Release MCP inspector sub-contexts promptly after each operation</issue_title>
<issue_description>## Objective

In pkg/cli/mcp_inspect_mcp.go, call cancel() immediately after each sequential MCP operation (ListTools, ListResources, ListPrompts) instead of deferring, to release context resources promptly.

Context

From discussion #18080 (go-sdk module review): The connectStdioMCPServer and connectHTTPMCPServer functions create three WithTimeout sub-contexts sequentially and cancel them via defer. Since only one operation runs at a time, cancelling immediately after each operation is complete (rather than at function return) releases timer resources sooner.

File to Modify

pkg/cli/mcp_inspect_mcp.go — connectStdioMCPServer and connectHTTPMCPServer functions

Change Required

// Before — deferred cancel held until function return
listToolsCtx, cancel := context.WithTimeout(ctx, MCPOperationTimeout)
defer cancel()
toolsResult, err := session.ListTools(listToolsCtx, ...)

// After — cancel immediately after operation completes
listToolsCtx, cancel := context.WithTimeout(ctx, MCPOperationTimeout)
toolsResult, err := session.ListTools(listToolsCtx, ...)
cancel()

Apply the same pattern to the ListResources and ListPrompts context pairs.

Acceptance Criteria

• All three sequential sub-context cancel() calls are invoked immediately after use (not deferred) in both connectStdioMCPServer and connectHTTPMCPServer
• make test-unit passes
• make agent-finish passes

Generated by Plan Command for issue #discussion #18080

• expires on Feb 27, 2026, 12:38 PM UTC

Comments on the Issue (you are @copilot in this section)

• Fixes [plan] Release MCP inspector sub-contexts promptly after each operation #18337

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[Copilot]

Pull request overview

This PR ensures MCP inspector operation timeout sub-contexts are cancelled immediately after each sequential operation, releasing timer resources promptly instead of holding them until the function returns.

Changes:

• Replace defer cancel() with an immediate cancel() after ListTools in both stdio and HTTP connection flows.
• Replace defer cancel() with an immediate cancel() after ListResources in both stdio and HTTP connection flows.
• Reformat a smoke-test JSON file used for PR push validation.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pkg/cli/mcp_inspect_mcp.go	Cancels per-operation WithTimeout contexts immediately after ListTools/ListResources complete to release timers sooner.
.github/smoke-test-22395402042.json	Formatting-only change to the smoke-test JSON file.

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[Copilot]

The PR description/acceptance criteria mention also applying this to ListPrompts, but this repo/file does not contain any ListPrompts call (only ListTools/ListResources). Please update the PR description (or the referenced acceptance criteria) to match the actual operations being changed, to avoid confusion for future readers.

[github-actions]

Smoke test summary
PRs: #18343 Release MCP inspector sub-contexts promptly after each operation; #18331 fix: update wasm golden fixtures to Copilot CLI 0.0.417
GitHub MCP: ✅
Serena MCP: ✅
Playwright: ✅
Web-fetch: ✅
File write+cat: ✅
Build: ✅
Overall: PASS

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