refactor(targets): unify queue/connectivity handling and coverage (#2953)

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
Co-authored-by: marshawcoco <marshawcoco@gmail.com>

crates/notify/AGENTS.md

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+# Notify Crate Instructions
+
+Applies to `crates/notify/`.
+
+`rustfs-notify` is the domain layer for bucket notification semantics. It
+builds rules, event dispatch flow, and config/runtime orchestration on top of
+shared plugin/runtime primitives from `rustfs-targets`.
+
+## Domain Boundaries
+
+- Keep notify-specific business logic here:
+  - bucket/rule evaluation
+  - event bridge and pipeline dispatch
+  - notify config reload orchestration
+- Keep shared runtime/plugin mechanics in `rustfs-targets`:
+  - do not duplicate replay worker lifecycle logic
+  - do not reimplement plugin descriptor/registry/catalog semantics
+  - do not move install/control-plane state into this crate
+
+## Runtime Layering Rules
+
+- `runtime_facade.rs` is the mutation/orchestration boundary:
+  activation, replace, stop workers, shutdown.
+- `runtime_view.rs` is read-only runtime observation:
+  active targets, metrics/health snapshots, runtime status snapshots.
+- `config_manager.rs` should map config to runtime updates through facade/view
+  and `runtime_target_id_for_subsystem`; avoid bypassing these boundaries.
+- `stream.rs` is a compatibility shim; new replay/runtime work should prefer
+  shared helpers in `rustfs-targets::runtime`.
+
+## Change Style
+
+- Preserve best-effort dispatch semantics and observability signals unless the
+  task explicitly requests behavior changes.
+- Reuse existing notify constants and subsystem mappings from `rustfs_config`.
+- Keep changes local and avoid cross-crate refactors from this crate unless
+  required by the task.
+
+## Testing
+
+- Keep unit tests close to changed modules.
+- Add regression tests for:
+  - rules to runtime target resolution
+  - runtime facade replace/shutdown behavior
+  - runtime view health/status/metrics snapshots
+- Suggested validation:
+  - `cargo test -p rustfs-notify`
+  - Focused: `cargo test -p rustfs-notify runtime_facade`
+  - Focused: `cargo test -p rustfs-notify runtime_view`
+  - Focused: `cargo test -p rustfs-notify config_manager`
+- Full gate before commit: `make pre-commit`