Bridge packed event collection through save import

docs/runtime-rehost-plan.md

@@ -18,14 +18,15 @@ Implemented today:
 - `rrt-runtime` exists with a deterministic calendar model, step commands, runtime summaries, and
   normalized runtime state validation
 - periodic trigger dispatch exists, including ordered periodic maintenance, dirty rerun `0x0a`, and
-  a first normalized runtime-effect surface
+  a normalized runtime-effect surface with staged event-record mutation
 - snapshots, state dumps, save-slice projection, and normalized state diffing already exist in the
   CLI and fixture layers
 - checked-in runtime fixtures already cover deterministic stepping, periodic service, direct trigger
   service, snapshot-backed inputs, and normalized state-fragment assertions
 
 That means the next implementation work is breadth, not bootstrap. The recommended next slice is
-normalized event-service breadth through staged event-record mutation and follow-on records.
+the `.smp` event-collection structural bridge across inspection, save-slice loading, import, and
+snapshot-backed fixtures.
 
 ## Why This Boundary
 
@@ -189,8 +190,10 @@ Current status:
 - periodic trigger ordering is implemented
 - normalized trigger-side effects already exist for world flags, company cash/debt, candidate
   availability, and special conditions
-- one-shot handling and dirty reruns are already covered by synthetic fixtures
-- the missing breadth is event-graph mutation and richer trigger-family behavior
+- one-shot handling, dirty reruns, and staged append/activate/deactivate/remove behavior are
+  already covered by synthetic fixtures
+- the remaining breadth is richer trigger-family behavior and target resolution, not first-pass
+  event-graph mutation
 
 ### Milestone 3: Persistence Boundary (partially complete)
 
@@ -212,8 +215,10 @@ Current status:
 
 - runtime snapshots and state dumps are implemented
 - `.smp` save inspection and partial save-slice projection already feed normalized runtime state
-- the remaining gap is broader captured-runtime and round-trip fixture depth, not the first
-  persistence surface
+- the packed event-collection summary now survives into loaded save slices and projected runtime
+  snapshots, but per-record packed bodies are still deferred
+- the remaining gap is broader captured-runtime and round-trip fixture depth plus deeper `.smp`
+  event-body decoding, not the first persistence surface
 
 ### Milestone 4: Domain Expansion
 
@@ -313,6 +318,7 @@ Keep:
 - cash, debt, and game-speed-related runtime fields when semantically relevant
 - collection contents and semantic counts
 - trigger-side effects
+- packed event-collection structural summaries when present
 
 ## Risks
 
@@ -340,47 +346,47 @@ The currently implemented normalized runtime surface is:
 - `runtime validate-fixture`, `runtime summarize-fixture`, `runtime export-fixture-state`,
   `runtime summarize-state`, `runtime import-state`, and `runtime diff-state`
 - deterministic stepping, periodic trigger dispatch, one-shot event handling, dirty reruns, and a
-  first normalized runtime-effect vocabulary
-- save-side inspection and partial state projection for `.smp` inputs
+  normalized runtime-effect vocabulary with staged event-record mutation
+- save-side inspection and partial state projection for `.smp` inputs, including the structural
+  packed event-collection summary
 
 Checked-in fixture families already include:
 
 - deterministic minimal-world stepping
 - periodic boundary service
 - direct trigger-service mutation
+- staged event-record lifecycle coverage
 - snapshot-backed fixture execution
 
 ## Next Slice
 
-The recommended next implementation slice is normalized event-service breadth through staged
-event-record mutation.
+The recommended next implementation slice is deeper `.smp` event persistence, starting from the
+structural bridge that already exists today.
 
 Target behavior:
 
-- allow one serviced record to append a follow-on runtime record
-- allow one serviced record to activate, deactivate, or remove another runtime record
-- stage those graph mutations during the pass and commit them only after the pass finishes
-- commit staged mutations in exact emission order
-- allow newly appended `0x0a` records to run in the dirty rerun after commit, but never in the
-  original pass snapshot
+- keep carrying the packed event collection across `inspect-smp`, `load-save-slice`,
+  `import-save-state`, snapshots, diffs, and fixtures
+- deepen that bridge from collection structure into per-record packed-body summaries
+- preserve the separation between parity-shaped packed state and executable normalized runtime state
+  until the packed layout is better decoded
 
 Public-model additions for that slice:
 
-- `RuntimeEventRecordTemplate`
-- `RuntimeEffect::AppendEventRecord`
-- `RuntimeEffect::ActivateEventRecord`
-- `RuntimeEffect::DeactivateEventRecord`
-- `RuntimeEffect::RemoveEventRecord`
+- packed per-record event summary types on the `.smp` side
+- optional runtime-side parity summaries for imported packed event records
+- no new executable `RuntimeEffect` variants by default in that slice
 
 Fixture work for that slice:
 
-- one synthetic fixture for append plus dirty rerun behavior
-- one synthetic fixture for cross-pass activate/deactivate/remove semantics
-- state-fragment assertions that lock final collection contents and per-record counters
+- one or more snapshot-backed fixtures that prove imported packed event state survives normalize and
+  diff paths
+- synthetic report/save-slice tests that lock the first per-record packed-body parse shape
+- state-fragment assertions that lock imported collection ids, version, and record counts
 
 Do not mix this slice with:
 
 - territory-access or selected-profile parity
 - placed-structure batch placement parity
 - shell queue/modal behavior
-- packed RT3 event-row import/export parity
+- direct translation of packed RT3 event rows into executable normalized effects