docs(08-05): the honest post-ALT record — KNOWN-LIMITATIONS + ROAD-GRAPH (escalation, no retirement)

Task 4, re-scoped per the plan's honest-FAIL branch: the c3 class is NOT
retired — every record now states the measured post-ALT truth.

- KNOWN-LIMITATIONS: the cross-metro section is the /cari-shaped record —
  WHAT CHANGED (ALT built, D-03 optimality green quoted) / what REMAINS
  (the CPU verdict FAIL lines quoted with date; the one-directional-
  Lipschitz wall named; the escalation open); the roadmap-pointer ALT row
  flips to Built (Phase 8) with the measured verdict — never 'not built'
  again
- ROAD-GRAPH: the ladder table gains the (c2) rung (EXECUTED, measured
  FAIL, the L=32 probe quoted); the decision paragraph states c2
  executed-verdict-fail and names the real remaining options; new 'The
  ARG2 binary layout' section (72-byte header, landmarkCount/
  landmarkQuantumS, u16 suffix + sentinels, the quantum knob's ≈6,553 s
  ceiling, the storage-name-vs-format-truth law); key facts carry the
  optimality gate and the ARG2 wording; the fork contract's build step
  teaches the landmark stage (no new commands)
- docs/CONFIGURATION.md: verify-only — all path/script claims still true,
  no edit needed
- staged as selective hunks; the tree's pre-existing doc-sync edits
  (battery paragraph, 'six maintainer scripts' intro) remain uncommitted

greps: 'Next-milestone item, not built' = 0; the measured p95 strings
quoted; (c2)/landmarkQuantumS/ARG2 all present; ARG1 appears only in
layout/router-pending contexts.

docs/KNOWN-LIMITATIONS.md

@@ -30,15 +30,33 @@ arah² routes over a snapshot of OpenStreetMap, and inherits OSM's gaps honestly
 
 Route computation runs inside Cloudflare Workers' free plan, whose per-request CPU
 allowance is small. On the real KL road graph, short product routes (2–8 km — the
-common search-and-reroute trip) measure 2–8 ms of Worker CPU and resolve inside the
-plan. Cross-metro routes (20–30 km) measured p95 38–93 ms against the same graph
-(`routing/scripts/measure-route-cpu.mjs`, LADDER HISTORY; Phase 6 plan summary), which
-is beyond what the free plan permits. Those trips therefore degrade honestly: the app
-shows the router-pending card — "the router is not ready for this trip" — instead of
-freezing or drawing a wrong line. The committed upgrade lever is ALT landmark
-preprocessing (a build-time graph layout that cuts A* steering cost); it is a
-next-milestone item and is **not** in this release. Workers Paid was rejected: it
-breaks the project's $0 mandate.
+common search-and-reroute trip) resolve inside the plan; cross-metro routes
+(20–30 km) do not. Those trips therefore degrade honestly: the app shows the
+router-pending card — "the router is not ready for this trip" — instead of freezing
+or drawing a wrong line. Workers Paid was rejected: it breaks the project's $0
+mandate.
+
+WHAT CHANGED (Phase 8, shipped 2026-10-25): the promised ALT landmark
+preprocessing was built — the ARG2 graph layout carries build-time landmark
+tables (L=24, quantum 0.1 s, coverage 0.980), the search steers with them, and
+optimality is verified: the D-03 gate reproduces the frozen pre-ALT record
+exactly (53/53 routed pairs within ±0.1%, max |Δ| 0.005%, verdict classes
+preserved — `node routing/scripts/measure-optimality-gate.mjs`).
+
+What REMAINS — the CPU verdict measured over budget, so the degradation stands:
+the 25-route gate printed `GATE FAIL: p95 152.788 ms exceeds the 8 ms budget`
+and the 100-pair cross-metro verdict `GATE FAIL: p95 185.692 ms exceeds the
+8 ms budget` (2026-10-25; the `--landmarks 32` probe measured worse:
+182.725 / 204.499 ms). The faster steering that would help is provably
+unsound here: the fromTable triangle bounds are one-directional Lipschitz
+(their u-side term needs the reverse edge, which a oneway does not provide),
+and the bidirectional search's shared potential is consistent only with
+two-sided families — the D-03 gate caught the four-family variant returning
+suboptimal routes (x038: 1234.6 s vs the 1214.8 s optimum) before it shipped.
+The honest escalation — direction-split potentials with a re-proven meet rule,
+Contraction Hierarchies, or Workers Paid — is open, documented in
+`docs/BUDGETS.md`'s c3 section. Full-speed routing is NOT claimed; only that
+the measurement is printed and the gate decides.
 
 ## The /cari command may be missing from the Telegram menu
 
@@ -71,12 +89,15 @@ items on the roadmap.
 
 ## What is being worked on next
 
-Three tracks target the limits above; none of them are in this release.
+Three tracks target the limits above. One of them — the ALT landmark layout —
+shipped in Phase 8; its measured outcome (optimality verified, CPU verdict
+still over budget) is recorded in the section above. The other two are not in
+this release.
 
 | Track | What it fixes | Honest status |
 | --- | --- | --- |
 | WASM-router | A client-side router compiled to WebAssembly — the static-hosted endgame where routing cost leaves the Worker entirely | Committed direction, not built |
-| ALT landmark preprocessing | The cross-metro CPU degradation (the section above) — build-time landmark layout cuts A* steering cost at $0 runtime | Next-milestone item, not built |
+| ALT landmark preprocessing | The cross-metro CPU degradation (the section above) — build-time landmark layout cuts A* steering cost at $0 runtime | Built (Phase 8, 2026-10-25): optimality verified; the CPU verdict measured over budget (p95 152.8/185.7 ms vs 8 ms) — the degradation stands |
 | Engine B | A fully client-side webview router — routing runs in the browser, the Worker serves only data | Future track, not built |
 
 ## Privacy in one paragraph