docs(quick-261026-d95): record isolated ALT research outcome

.planning/STATE.md

@@ -5,7 +5,7 @@ milestone_name: routing-engine-upgrades-and-extras
 status: ready_to_plan
 stopped_at: "F1 remediation applied (debug alt-potential-4x-slowdown RC-1): clean-columns-only ALT containment in routing/src/astar.ts — per-node sentinel skip removed; suite re-spec'd RED-first (A11) + new A13 mixed-column case; new committed oracle sweep measure-astar-oracle-sweep.mjs 0/200 suboptimal; CPU back in the pre-ALT band (p95 136.6 ms this host vs 1037.6 pre-fix — honest c3 FAIL vs 8 ms stands); D-03 gate green. Commits c071e20 / 2a5a0b5 / 97d6e35. NEXT: maintainer R2 upload + the SC-1 escalation decision (unchanged)"
 last_updated: "2026-10-25T14:15:06.953Z"
-last_activity: 2026-10-25
+last_activity: 2026-10-26
 progress:
   total_phases: 4
   completed_phases: 2
@@ -28,7 +28,7 @@ See: .planning/PROJECT.md (updated 2026-10-22)
 Phase: 08.1
 Plan: Not started
 Status: Ready to plan
-Last activity: 2026-10-25
+Last activity: 2026-10-26 - Completed quick task 261026-d95: isolated ALT direction-split research (NO-GO; no production integration)
 
 Progress: [██████████] 100%
 
@@ -82,6 +82,7 @@ None yet.
 | # | Description | Date | Commit | Directory |
 |---|-------------|------|--------|-----------|
 | 261024-001 | Replace logo references with master assets | 2026-10-24 | TBD | [261024-001-logo-asset-replacement](./quick/261024-001-logo-asset-replacement/) |
+| 261026-d95 | Isolated ALT direction-split research: proved and measured, NO-GO for integration | 2026-10-26 | 9a671bd | [261026-d95-alt-direction-split-isolated-research-si](./quick/261026-d95-alt-direction-split-isolated-research-si/) |
 
 ## Deferred Items