fix: harden refresh generation guards

[karthiknadig]

This follow-up fixes the post-merge correctness gap left after #386.

• make refresh notification emission generation-aware and atomic with the generation check
• keep stale refresh state from syncing back into shared locators after a newer configure
• replace the missing-env one-shot boolean with generation-stamped reservation semantics so newer generations can supersede stale reservations
• add regression tests for stale-generation reporting and missing-env reservation behavior

Fixes #390

[github-actions]

Performance Report (Linux) ➖

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta	Change
Server Startup	1ms	1ms	1ms	0ms	0%
Full Refresh	81ms	349ms	77ms	4ms	0%

Results based on 10 iterations. P50 = median, P95 = 95th percentile.

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Legend

• 🚀 Significant speedup (>100ms faster)
• ✅ Faster than baseline
• ➖ No significant change
• 🔺 Slower than baseline (>100ms)
• ⚠️ Significant slowdown (>500ms)

[github-actions]

Test Coverage Report (Linux)

Metric	Value
Current Coverage	67.9%
Base Branch Coverage	67.5%
Delta	.4% ✅

---

Coverage increased! Great work!

[github-actions]

Performance Report (macOS)

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta
Server Startup	55ms	497ms	46ms	9ms
Full Refresh	99ms	33526ms	92ms	7ms

Results based on 10 iterations. P50 = median, P95 = 95th percentile.

---

Legend

• 🚀 Significant speedup (>100ms faster)
• ✅ Faster than baseline
• ➖ No significant change
• 🔺 Slower than baseline (>100ms)
• ⚠️ Significant slowdown (>500ms)

[github-actions]

Performance Report (Windows) ➖

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta	Change
Server Startup	9ms	11ms	7ms	2ms	28.6%
Full Refresh	144ms	348ms	111ms	33ms	29.7%

Results based on 10 iterations. P50 = median, P95 = 95th percentile.

---

Legend

• 🚀 Significant speedup (>100ms faster)
• ✅ Faster than baseline
• ➖ No significant change
• 🔺 Slower than baseline (>100ms)
• ⚠️ Significant slowdown (>500ms)

[github-actions]

Test Coverage Report (Windows)

Metric	Value
Current Coverage	64.21%
Base Branch Coverage	63.72%
Delta	0.49% ✅

---

Coverage increased! Great work!

[Copilot]

Pull request overview

This PR hardens refresh correctness in PET’s JSONRPC server by making refresh side effects (notifications, shared locator state sync, and missing-env follow-up work) generation-aware so stale work can’t leak across configure boundaries.

Changes:

• Added a generation-guarded Reporter wrapper to atomically suppress stale refresh notifications after configuration generation advances.
• Prevented stale refreshes from syncing refresh-state back into the long-lived shared locator graph.
• Reworked the missing-environment follow-up “one shot” into a generation-stamped reservation so newer generations can supersede stale reservations, and added regression unit tests.

Show a summary per file

File	Description
crates/pet/src/jsonrpc.rs	Adds generation-aware guards for refresh notifications/state sync and replaces missing-env one-shot tracking with generation-stamped reservation + tests.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0