J1: the cliff tunnel (seam, six propped stretches, dark, lights), travel Valley <-> Cove through the sea cave, a save file per worldlet; New World has no Where (--dev-worldlets to try others)

docs/WORLDLETS_DESIGN.md

@@ -1,7 +1,34 @@
 # Worldlets design
 
-Status: **W0-W3 built** (the Cove, without its stream yet); the rest is
-planned. The journey between
+Status: **W0-W3 and J1 built** (the Cove without its stream yet; the
+tunnel single-player only); the rest is planned.
+
+*As built in J1:*
+- `scripts/world/tunnel.gd`: the seam (an outcrop on the clifftop strip,
+  7 m in from the edge, its angle from the seed) and the tunnel space, out
+  of sight 260 m under the island: a CSG rock block with the landings and
+  six sloping stretches cut out (6 m on, 4 m down each, switching back on
+  two lanes: 24 m down), then a sea cave. Faces (`tunnel_face.gd`) answer
+  like boulders, so the pick works on them: tier 3 only ("Too hard: you
+  need a better pick"), 10 blows for the seam and 15 per stretch. Each
+  stretch must be propped (2 wood, [E] at its mouth) before the next face
+  takes a blow ("It's loose..."): 10 wood all the way down.
+- Underground: no sun, moon, sky reflections or sky-tinted fog
+  (`day_night.underground`), no weather, no lake water, sheltered. Candles
+  and torch stands place anywhere on its floor and save as ordinary pieces.
+- Walking out of the sea cave's mouth travels (`world.travel()`): the
+  worldlet you leave is saved, your character and the clock go with you,
+  and the other loads, arriving at its sea cave (`sea_cave.gd`, on the
+  Cove's beach where the headland starts). [E] at the cave goes back up the
+  same tunnel to its bottom, once it's dug through.
+- Saves: `world.json` is the home worldlet's state, as before;
+  others are `worldlets/<id>.json`; meta.json's `worldlet` is where you
+  are, `home` where you began, `arrive` where the next load puts you.
+- `tests/test_tunnel.gd`: dig through, walk every stretch down and back
+  up, light it, reload, out to the Cove, back up, out at the top, and the
+  chest at home is still there.
+- Not yet: Old Tam's tip about the seam, the Guide page, and travel on a
+  server (J3: the tunnel isn't built online). The journey between
 worldlets is §10, and the two ways to play (the journey, or one land) are in
 its decisions.
 
@@ -17,9 +44,10 @@ its decisions.
 - Sea fish in `data/fish.json`: mackerel (common) and cod, which only bites
   in water 2.2 m or deeper (a per-fish `min_depth`). Grilled at a campfire,
   salted, or smoked, like the lake's.
-- Running from the source, the New World and Host pages also offer
-  worldlets that aren't starts, marked "(testing)", so the Cove can be
-  played before the tunnel exists. Release builds offer only the Valley.
+- New World has no "Where": the journey always begins in the Valley (the
+  Host page keeps it, for One land mode). Started with
+  `godot --path . -- --dev-worldlets`, New World and Host offer every
+  worldlet, the others marked "(testing)", to try one directly.
 - No sea stacks without a sea cliff.
 - Tests: `test_cove` (walk onto the pier, catch a mackerel off its end, cod
   only in deep water), and the Cove in `test_terrain_edges` and
@@ -302,7 +330,7 @@ tunnel goes **down**, inside the cliff, from the clifftop to the shore.
 - **Props:** each new stretch needs a **timber prop** (2 wood) set at its
   mouth before you can dig the next. Leave one out and the face won't take
   another blow ("It's loose: prop it first"); nothing caves in on you, so
-  it's a cost, not a trap. That's about 12 wood all the way down.
+  it's a cost, not a trap. That's 10 wood all the way down.
 - **Light:** the tunnel has no daylight at all. Every stretch is pitch dark
   until you bring light: a torch in your hand works, but your hands are full
   with the pick, so the way to do it is to set **candles and torch stands**