Lane E R18 (v4.0-alpha): the other 4 towns' road geometry (data-only) + Overpass retry

Newtown/Fremantle/Bendigo/Castlemaine now schema v2 with roads[] (1086/622/1552/397 real streets),
same fidelity cut (street tier only). Data-only: only katoomba gates the round; A hardens against these.
build_towns.py: added Overpass retry/backoff (public API 504s under load — hit one mid-run).

The poster-clearance finding is SYSTEMATIC: it reproduces on all 5 real-road towns, every seed (23
checks, -0.9 to -4.7m), confirming it's plan-level poster placement (A's pickVenues/POSTER_CLEAR), not
town data. Scoping holds: only the real/* v2 path fails; synthetic + fixtures + classic + default boots
stay green. A's one fix generalizes to all five. ODbL: raw roads committed, SOURCES.md current.

-> Lane A: all 5 towns' roads live; the systematic poster finding is yours to resolve + re-pin goldens.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/LANES/LANE_E_NOTES.md

@@ -35,9 +35,18 @@ plan-level poster placement, not cache errors. Not a fidelity artifact either: t
 real primary town streets, so trimming roads wouldn't fix it. Golden settles after A's fix (pre-fix
 value `0x6014a8e6`). Handshake E→A: **katoomba roads live + this finding**.
 
-**Other 4 towns:** roads produced + committed as data-only (A hardens against them as they land; only
-katoomba gates the round). Roads are ODbL (© OSM contributors); raw responses committed, `SOURCES.md`
-updated with the roads tier + the fidelity cut.
+**Other 4 towns** (data-only; A hardens against them, only katoomba gates): all now v2 —
+newtown_real 1086 roads, bendigo_real 1552, fremantle_real 622, castlemaine_real 397 (dense/regional
+towns → bigger graphs; real data, A's DP + density classification handle it). Roads are ODbL, raw
+committed, `SOURCES.md` updated. (Robustness: `build_towns.py` gained Overpass retry/backoff — the
+public API 504s under load.)
+
+**The finding is SYSTEMATIC** — the spine-poster clearance fails identically on **all 5** real-road
+towns, every seed (23 checks, −0.9 to −4.7 m). That it reproduces across five different real street
+grids confirms it's **plan-level poster placement, not town data** → squarely A's (`pickVenues` /
+`POSTER_CLEAR`). Scoping holds: **only the `real/*` v2 path fails — synthetic + fixtures + classic +
+default boots are all green** (roads[] is the only changed path, per the alpha law). A's one fix
+generalizes to all five.
 
 ## Round 17 — v3.2 THE SCOUT: real town caches + the verify fix ⟨v3.2 amendment⟩
 

pipeline/build_towns.py

@@ -17,7 +17,7 @@ attribution ships IN every cache (`license`/`attribution`) + `SOURCES.md`. Hours
 registry supplies them at plan time (contract shop = {id,name,type,lat,lon,suburb}). Overpass is an
 outward-facing fetch (John-authorized scout, once per town, raw cached).
 """
-import os, sys, json, re, math, time, datetime, urllib.request, urllib.parse
+import os, sys, json, re, math, time, datetime, urllib.request, urllib.parse, urllib.error
 
 ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 TOWNS_DIR = os.path.join(ROOT, "web", "assets", "towns")
@@ -98,6 +98,22 @@ def haversine_m(a, b):
     return 2 * R * math.asin(min(1.0, math.sqrt(h)))
 
 
+def overpass_post(q):
+    """POST an Overpass query with retry/backoff — the public API 504s / times out under load."""
+    req = urllib.request.Request(OVERPASS, data=urllib.parse.urlencode({"data": q}).encode(),
+                                 headers={"User-Agent": UA})
+    for attempt in range(4):
+        try:
+            with urllib.request.urlopen(req, timeout=180) as r:
+                return json.load(r).get("elements", [])
+        except (urllib.error.HTTPError, urllib.error.URLError, TimeoutError) as e:
+            if attempt == 3:
+                raise
+            wait = 15 * (attempt + 1)
+            print(f"    Overpass {getattr(e, 'code', type(e).__name__)} — retry {attempt + 1}/3 in {wait}s")
+            time.sleep(wait)
+
+
 def fetch_raw(key, bb, refetch):
     """Return the raw Overpass elements list, cached in-repo so re-runs never re-fetch."""
     os.makedirs(RAW_DIR, exist_ok=True)
@@ -110,10 +126,7 @@ def fetch_raw(key, bb, refetch):
          f'({bb["minLat"]:.5f},{bb["minLon"]:.5f},{bb["maxLat"]:.5f},{bb["maxLon"]:.5f});'
          f'out center;')
     print(f"  [{key}] fetching Overpass (bounded {bb['minLat']:.3f},{bb['minLon']:.3f} … {bb['maxLat']:.3f},{bb['maxLon']:.3f})")
-    req = urllib.request.Request(OVERPASS, data=urllib.parse.urlencode({"data": q}).encode(),
-                                 headers={"User-Agent": UA})
-    with urllib.request.urlopen(req, timeout=150) as r:
-        els = json.load(r).get("elements", [])
+    els = overpass_post(q)
     fetched = datetime.date.today().isoformat()
     json.dump({"fetchedAt": fetched, "endpoint": OVERPASS, "query": q, "bbox": bb, "elements": els},
               open(path, "w"), indent=1)
@@ -132,10 +145,7 @@ def fetch_roads_raw(key, bb, refetch):
          f'({bb["minLat"]:.5f},{bb["minLon"]:.5f},{bb["maxLat"]:.5f},{bb["maxLon"]:.5f});'
          f'out geom;')
     print(f"  [{key}] fetching Overpass roads (highway ways, bounded)")
-    req = urllib.request.Request(OVERPASS, data=urllib.parse.urlencode({"data": q}).encode(),
-                                 headers={"User-Agent": UA})
-    with urllib.request.urlopen(req, timeout=150) as r:
-        ways = json.load(r).get("elements", [])
+    ways = overpass_post(q)
     json.dump({"fetchedAt": datetime.date.today().isoformat(), "endpoint": OVERPASS, "query": q,
                "bbox": bb, "elements": ways}, open(path, "w"), indent=1)
     time.sleep(2)