Summary

When memory.compression.probe is enabled and a compaction probe HardFail occurs, the /compact command now correctly shows "Compaction rejected: summary quality below threshold. Original context preserved." instead of the misleading "Context compacted successfully." message.

Changes

• Fix: Updated the /compact handler in crates/zeph-core/src/agent/mod.rs to explicitly match on CompactionOutcome variants instead of blindly accepting all Ok(_) results
• Message on success: "Context compacted successfully." (for Compacted | NoChange)
• Message on rejection: "Compaction rejected: summary quality below threshold. Original context preserved." (for ProbeRejected)
• Updated: CHANGELOG.md entry added

Testing

• ✅ All pre-commit checks pass: cargo +nightly fmt --check, cargo clippy, 6090 tests
• ✅ Code review: Approved (fix is minimal, exhaustive match on all CompactionOutcome variants)
• ✅ Testing validation: Approved (existing test coverage sufficient, no regressions)
• ✅ Live reproduction verified in CI-23: probe score=0.75, hard_fail_threshold=0.90 → user now sees correct rejection message

Issue

Closes #2058

Related

• Compaction probe feature: PR research: task-continuation metric for post-compaction validation #1609
• Probe metrics in TUI: PR feat(tui): add compaction probe metrics to TUI dashboard #2049
• Probe in init wizard: PR feat(core): add --init wizard step for compaction probe config #2048