Memoize flag alias resolution by context

docs/roadmap/audit/catalog.md

@@ -1,6 +1,6 @@
 # Consolidated audit catalog
 
-Status: **12 distinct open findings: 12 P3**, consolidated from 30
+Status: **11 distinct open findings: 11 P3**, consolidated from 30
 numbered entries in seven audit documents. Reviewed audit state:
 `db732e3a1de55c844f77870e1c6db683c2685d5d`.
 
@@ -274,6 +274,10 @@ ownership; it is separate from the closed-reporting-handle retention in F07.
 
 ## F13 — P3: Flag-alias compilation repeatedly walks shared chain suffixes
 
+**Complete.** Each effective context memoizes its target resolutions, including
+inactive endpoints, while retaining canonical precedence and cycle diagnostics.
+Focused alias and discovery tests pass, including shared suffixes and registration.
+
 For A chained effective flag mappings across C contexts, independent target
 walks can perform Θ(CA²) target examinations, including inactive chains. Each
 source repeats work already performed for another source's suffix.

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Audit remediation implementation plan
 
-Status: in progress; Stages 1–14 complete.
+Status: in progress; Stages 1–15 complete.
 
 Baseline: `d492c7747175c01a53261206c2b4356e53453621`. Before this sprint,
 intervening changes recorded decisions and retired the completed older
@@ -500,6 +500,12 @@ clear, with selected syntax and provenance preserved.
 
 ## Stage 15 — Memoize each context's flag-alias graph
 
+**Complete.** Context-local traversal memoizes canonical and unavailable
+endpoints, with an active stack for cycle diagnostics. Source review confirms
+resolved suffixes are reused within each context. Focused alias, registration,
+cycle and discovery tests passed offline with Go 1.27.0 and `-mod=readonly`,
+including shared suffixes and unavailable destinations.
+
 Findings: F13. Source: `flag_aliases.go`.
 
 1. Replace independent suffix walks with context-local visitation and memoized