firestore-reads: enable batch_privacy_memoize 0->5 (WQ16, config-only) (#23554)

## Summary

Config-only: enable `batch_privacy_memoize` at 5% in the prod
`FIRESTORE_READ_LEVERS` literal. All 16 existing keys are byte-identical
to the served literal on backend-02109-qzv; the only delta is the added
`"batch_privacy_memoize":5`.

Behavior code already merged and served via #23072 (merge d90643d,
ancestor of the serving release; memoized per-job privacy assertion).
The lever key is in main `KNOWN_LEVERS` (firestore_read_levers.py:46).
The lever has been dark at 0 since then; this PR makes it addressable at
the cautious first ramp step.

Caller pool being addressed (loop snapshot
baseline-2026-10-24T09-45Z-pre-bpm.json, 1h caller window, window_end
2026-10-24T08Z): `database.batch_pipeline_privacy:read` ~3.36M reads/h
across backend-sync + backend-sync-backfill (not_found storms on `other`
+ lookups on users/conversations) ≈ 81M/day at 1hx24 — the top measured
origin. Expected saving is unknown until the ramp readout; predicted
50M/day is the caller-pool hypothesis registered in the loop ledger, not
a measurement.

## Product invariants affected

- INV-FSR-LEVERS — lever percentage changes only via this literal;
absent keys remain 0/off; REPLACE-mode literal kept complete (17 keys)
at all sites.
- INV-READ-BUDGET — at 5% cohort the memoized path serves most per-write
privacy reads from the per-job memo; off-cohort behavior is
byte-identical to today.
- INV-MEM-4 — required citation: this PR touches the locked
runtime_env/charts path family this invariant guards. It changes only a
Firestore read-lever percentage (read-path memoization of an existing
per-write privacy assertion); it adds no promotion route, fast-track
pass, or canonical-lineage change.

## Verification

- Literal consistency: all 54 literal occurrences under backend/ parsed
and compared; every deployed-literal site (runtime_env/_base.yaml x12,
rendered runtime_env.yaml x24, 4 listen/pusher chart values, flag
registry, both pinned contract tests) equals the exact 17-key target;
the 10 partial literals in test_fsr_s5_action_items.py are intentional
single-lever fixtures, unchanged.
- Contract tests: `backend/.venv/bin/python -m pytest
backend/tests/unit/test_render_backend_runtime_env.py
backend/tests/unit/test_verify_pusher_config_references.py -q` → 121
passed.
- Loop-side pre-enable baseline pinned (post-code-serve, pre-enable):
baseline-2026-10-24T09-45Z-pre-bpm.json, coverage 0.685,
missing_services [].
- No GCP write tier used; measurement used the read-only prod tier.

UI-Evidence: none — backend config only, no UI change.

Failure-Class: none

## Rollout and rollback

Rollout: loop-owned lever config at 5%, then per the loop runbook ramp
rule (verify PASS x2 ticks after 3h → 100% candidate; grades on absolute
caller reads vs the pinned baseline). Deploy train order remains listen
→ pusher → Cloud Run (rollout lead owns the train). Rollback: revert
this commit (or a follow-up config PR setting the key to 0), then the
same train.

Author: Git-on-my-level

backend/charts/backend-listen/dev_omi_backend_listen_values.yaml

@@ -228,7 +228,7 @@ env:
   - name: FIRESTORE_READ_LEDGER
     value: "1"
   - name: FIRESTORE_READ_LEVERS
-    value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+    value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
   - name: FSR_QUEUE_AGE_PUBLISHER
     value: "1"
   - name: FSR_QUEUE_AGE_LEASE_SECONDS

backend/charts/backend-listen/prod_omi_backend_listen_values.yaml

@@ -222,7 +222,7 @@ env:
   - name: FIRESTORE_READ_LEDGER
     value: "1"
   - name: FIRESTORE_READ_LEVERS
-    value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+    value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
   - name: FSR_QUEUE_AGE_PUBLISHER
     value: "1"
   - name: FSR_QUEUE_AGE_LEASE_SECONDS

backend/charts/pusher/dev_omi_pusher_values.yaml

@@ -192,7 +192,7 @@ env:
   - name: FIRESTORE_READ_LEDGER
     value: "1"
   - name: FIRESTORE_READ_LEVERS
-    value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+    value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
   - name: FSR_QUEUE_AGE_PUBLISHER
     value: "0"
   - name: FSR_QUEUE_AGE_LEASE_SECONDS

backend/charts/pusher/prod_omi_pusher_values.yaml

@@ -203,7 +203,7 @@ env:
   - name: FIRESTORE_READ_LEDGER
     value: "1"
   - name: FIRESTORE_READ_LEVERS
-    value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+    value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
   - name: FSR_QUEUE_AGE_PUBLISHER
     value: "0"
   - name: FSR_QUEUE_AGE_LEASE_SECONDS

backend/deploy/runtime_env.yaml

@@ -31,7 +31,7 @@ environment_shared:
         REPEAT_WORK_LLM_VERSION: {value: '2026-10-16-v1', category: rollout}
         SYNC_POLL_BACKOFF_ENABLED: {value: 'false', category: rollout}
         FIRESTORE_READ_LEVERS:
-          value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+          value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
           category: rollout
         FSR_QUEUE_AGE_PUBLISHER:
           value: '1'
@@ -539,7 +539,7 @@ environment_shared:
         REPEAT_WORK_LLM_VERSION: {value: '2026-10-16-v1', category: rollout}
         SYNC_POLL_BACKOFF_ENABLED: {value: 'false', category: rollout}
         FIRESTORE_READ_LEVERS:
-          value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+          value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
           category: rollout
         FSR_QUEUE_AGE_PUBLISHER:
           value: '0'
@@ -800,7 +800,7 @@ environment_shared:
       FIRESTORE_READ_LEDGER:
         value: '1'
       FIRESTORE_READ_LEVERS:
-        value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+        value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
         category: rollout
       FSR_QUEUE_AGE_PUBLISHER:
         value: '0'
@@ -1000,7 +1000,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -1384,7 +1384,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -1747,7 +1747,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -2104,7 +2104,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -2329,7 +2329,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -2410,7 +2410,7 @@ environment_shared:
             version: latest
         env:
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -2496,7 +2496,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -2584,7 +2584,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'
@@ -2658,7 +2658,7 @@ environment_shared:
           FIRESTORE_READ_LEDGER:
             value: '1'
           FIRESTORE_READ_LEVERS:
-            value: '{"action_items_page":100,"backfill_task_reads":100,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
+            value: '{"action_items_page":100,"backfill_task_reads":100,"batch_privacy_memoize":5,"candidates_page":100,"canonical_statuses_dedupe":100,"deletion_marker_cache":100,"historical_scan_memo":100,"ledger_purge_coalesce":100,"mcp_conversation_cards_cache":100,"memory_list_index_window":25,"people_scan_dedupe":0,"queue_age_sample_budget":0,"request_read_dedupe":100,"serving_config_cache":100,"singleton_loops":100,"subscription_cache":100,"usage_month_cache":100}'
             category: rollout
           FSR_QUEUE_AGE_PUBLISHER:
             value: '0'