Python rewrite of the Urb/Homemaker stack
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Claude c0c47a6e2d
DESIGN.md §38: the plateau is an objective-gradient problem, not a search problem
Diagnostic investigation of why search stalls in local minima. Adds
experiments/diag_exposure_frontage.py (frontage/exposure/value reports,
no search run required) and records the findings as §38.

Core mechanism: quality_uncrinkliness returns a hard 0.0 for any leaf with
no daylit wall, and since leaf quality is a product feeding
value += quality * rate * area, every buried room contributes exactly zero
value while still costing. 45-56% of interior leaves are in this state under
the default construction stack.

Consequences measured, not inferred:
- Deleting a buried O leaf improves the score x85, a buried C leaf x62.
  Nothing pins circulation or outside space, so the search is rewarded by two
  orders of magnitude for deleting the circulation spine. This retro-explains
  §18, §21/§22 and the level-not-connected fails surviving >1M evals.
- Closed-form frontage bound: every interior leaf needs exposed wall
  L >= A/(1.6202*h). harbor-house supplies 54m against 148m needed (2.7x
  short), maple-court 56 vs 162; health-centre and programme-house are
  feasible. The corpus plateau is predicted by frontage deficit alone.
- Crinkliness is tiered SOFT but 60-100% of its fails are zero-exposure,
  which is topological, so §37.1's tiered comparator is mis-informed about
  the largest fail category.
- The missing-space cascade emits one extra fail per declared size/width/
  proportion key, so under 0.5^n a missing room is weighted 4x differently
  depending on patterns.config verbosity.

Filed as homemaker-py-ssz, hxi, tdp, gvb, 1i8 (plus bdf for the pre-existing
fresh-clone test failures found en route).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MJ84Feep79Hhm3E4zZJmnB
2026-08-25 23:18:20 +00:00
.beads Ignore beads auto-import tracking marker 2026-08-25 23:01:40 +00:00
.claude Scaffold homemaker-py with validated geometry port 2026-06-10 20:50:20 +01:00
examples homemaker-py-1s3: multi-use leaves as permanent design goal (§26 path b) 2026-07-31 00:16:12 +01:00
experiments DESIGN.md §38: the plateau is an objective-gradient problem, not a search problem 2026-08-25 23:18:20 +00:00
src/homemaker_layout homemaker-py-pek: delete dead first process_storey definition 2026-08-05 16:57:20 +01:00
tests homemaker-py-sd3: fix vacuous 94g keep-better guard (collapse_insearch leak) 2026-08-05 07:52:44 +01:00
.gitignore bd init: initialize beads issue tracking 2026-06-11 23:27:11 +01:00
AGENTS.md bd init: initialize beads issue tracking 2026-06-11 23:27:11 +01:00
CLAUDE.md homemaker-py-2g7.5: CP-SAT exact room-code assignment (seeder + reassign op) 2026-08-04 09:19:36 +01:00
DESIGN.md DESIGN.md §38: the plateau is an objective-gradient problem, not a search problem 2026-08-25 23:18:20 +00:00
pyproject.toml homemaker-py-2g7.5: CP-SAT exact room-code assignment (seeder + reassign op) 2026-08-04 09:19:36 +01:00
README.md update 2026-07-31 09:57:45 +01:00

homemaker-layout

Programme-driven building-layout search over slicing trees. A clean-room Python successor to the Perl Urb project, intended to eventually be 100% Python.

Why a rewrite

Urb represents a building as a binary slicing tree where room sizes are derived top-down from division ratios. That makes room area an emergent property of every cut above it, which:

  • gives the genome low locality (a cut near the root rescales every descendant),
  • makes target room sizes nearly impossible to hit, so the gaussian size penalty dominates fitness, and
  • defeats crossover (transplanted subtrees lose their proportions).

homemaker inverts this: leaves carry target dimensions from the programme and division ratios are solved bottom-up for a fixed topology. The evolutionary search then only explores topology + types + adjacency.

Phase plan

  1. Solver experiment: port Urb's geometry, re-solve ratios from programme targets, score the result against the original via the Perl oracle.
  2. Native Python fitness (retire the Perl oracle).
  3. Memetic search: canonical slicing genome + high-locality operators + Nelder-Mead inner loop.
  4. Penalty reshaping: lexicographic (-n_fails, fitness) outer-search comparison.
  5. Representation upgrade: canonical slicing encoding + bottom-up shape feasibility, scaled to larger programmes.
  6. Search-quality experiments (current): a long running series of opt-in levers tried against the harbor-house, health-centre, and programme-house example corpora — leaf-sharing, finish-time cell→room collapse, ruin-and-recreate LNS, 2-opt polish, multi-use/co-located leaves, adjacency-graph and bubble-diagram fitness signals, and more. Most of these are negative/null results kept as opt-in flags or reference code rather than defaults. See DESIGN.md §11 onward for the full, numbered experiment log with methodology and results for each.

Layout

  • src/homemaker_layout/dom.py — read/write Urb .dom YAML into a Node tree.
  • src/homemaker_layout/geometry.py — faithful port of Urb's top-down geometry.
  • src/homemaker_layout/programme.py — parse patterns.config space requirements.
  • src/homemaker_layout/solver.py — bottom-up ratio solve (scipy).
  • src/homemaker_layout/fitness.py — native Python fitness evaluator.
  • src/homemaker_layout/fitness_cmd.pyhomemaker-fitness CLI (drop-in for urb-fitness.pl).
  • src/homemaker_layout/collapse_cmd.pyhomemaker-collapse CLI: finish-time global cell→room relabel of a .dom.
  • src/homemaker_layout/graph.py — leaf-adjacency graph for programme-driven checks.
  • src/homemaker_layout/genome.py — topology genome: base-floor tree + per-storey deltas.
  • src/homemaker_layout/operators.py — high-locality mutation and subtree crossover.
  • src/homemaker_layout/innerloop.py — ratio optimisation inner loop (Nelder-Mead / CMA-ES).
  • src/homemaker_layout/driver.py — memetic search outer loop.
  • src/homemaker_layout/evolve.pyhomemaker-evolve CLI entry point.
  • src/homemaker_layout/oracle.py — legacy Perl shim, kept for cross-validation only.
  • src/homemaker_layout/bubble.py — 3D bubble-diagram adjacency fitness-signal prototype (DESIGN.md §27); validated null, not wired into fitness.py — reference only.