perf: optimize http/2 request hot path

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
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• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

Profiled the H2 client and removed the main client-side hot spots:

• completeRequest: fast-path in-order completions by advancing kRunningIdx (like H1) instead of an O(n) indexOf+splice; out-of-order completions keep the splice path
• use on instead of once for self-removing stream handlers, and skip listener removal on already-closed streams (handlers null-guard on the stream state)
• single pre-shaped stream state object (stable hidden class), finalizeRequest/openStream hoisted out of per-request closures
• cache the session ref state to skip redundant ref()/unref() calls (session ref proxies to the socket)
• memoize getProtocolFromUrlString

Benchmarks (single connection, local H2 server, interleaved A/B vs main): +5-6% req/s at 100 parallel requests, +27% at 1000, +51% at 2000; +15% with a 10-connection Pool. Remaining cost is dominated by node core session.request() internals.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.08911% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.43%. Comparing base (7d78f7d) to head (86faa6a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h2.js	90.05%	18 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #5483 +/- ##
==========================================
- Coverage 93.45% 93.43% -0.03% 
==========================================
Files 110 110 Lines 37147 37247 +100 ==========================================
+ Hits 34717 34800 +83 - Misses 2430 2447 +17 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.