This session is being continued from a previous conversation that ran out of context. The summary below covers the earlier portion of the conversation.

Analysis:

Let me chronologically analyze the conversation:

1. Session Start: User invoked /cd skill which reads .working_project (got "di") and then reads code.debt.md to propose first unchecked item.

2. First debt item - Table cell editing: The first unchecked item was about table cell editing (Enter/Tab navigation). I explored the codebase and found it was already implemented in Events.ts. User confirmed and had me check off the sub-items. User also added a new sub-item "all tables and lists (eg, parts)".

3. Duplicate bug report: User reported "dup creates 5 dups (four extra unwanted)". I started investigating duplicate_selected() in Engine.ts and the hit_target system. User interrupted - said their root SO was corrupted.

4. Back to /cd: User said /cd again. I read code.debt.md, proposed "new root -> invisible" as next item. User checked it off themselves, told me to read the NEXT item.

5. Load scenes without reloading: The next unchecked item was "Load scenes without reloading — parse, teardown old scene, build new one in-place". User approved exploring this. I used an Explore agent to thoroughly understand the scene loading architecture.

6. Proposal: I proposed extracting load_scene() from Engine.setup() phase 2. User asked "can setup call this new function?" - I confirmed the clean split. User approved with "y".

7. Implementation:

- Added Portable_Scene import to Engine.ts

- Extracted load_scene(saved: Portable_Scene | null) method from setup()

- Updated Scenes.ts: changed load_from_text to return data, new_scene() returns Portable_Scene, import_from_file takes callback

- Added visible?: boolean to Portable_SO interface (was already serialized/deserialized but missing from type)

- Updated D_Library.svelte: click handler uses parse_text() + engine.load_scene()

- Updated Details.svelte: new-scene button calls engine.load_scene(scenes.new_scene())

- All checks passed (svelte-check 0 errors, vitest 417 tests passing)

8. Bug: rendered SOs look wrong: User reported "stretch is flat, room has bloated clones" etc. I identified the root cause: constants were being restored AFTER deserialization and rebind_formulas, but rebind_formulas (Constraints.ts line 317) evaluates formulas immediately. In the old flow, scenes.load() called restore_constants() BEFORE returning, so constants were set before any deserialization. I moved constant restoration to before the deserialization loop.

9. Stretch still flat: User said stretch still loads flat. I read stretch.di - it had formulas referencing constants template_w and template_th. User then found the bug themselves - they had broken the stretch.di file data (removed the formula from y.length, making it a bare number). They fixed it and stretch loaded fine.

10. Duplicate bug with drawer: User showed a screenshot of a duplicated drawer with wrong geometry on the dup's side and back. Key evidence: option-click (insert_child_from_text) works perfectly, but duplicate produces broken geometry. Refreshing fixes it.

11. Investigating duplicate bug: I started comparing duplicate_selected() vs insert_child_from_text(). Key findings so far:

- insert_child_from_text calls constraints.propagate_all() once after all SOs are rebound

- duplicate_selected calls constraints.propagate(clone) per clone individually

- The token remapping in duplicate_selected tries to match token.object (which contains NAMES like '', 'self', 'A') against old_to_new map (which maps IDs to IDs) - this remapping is effectively a no-op

- I was reading propagate() vs propagate_all() to understand the difference when the summary was requested

Key files modified:

• di/src/lib/ts/render/Engine.ts - extracted load_scene(), added import for Portable_Scene

• di/src/lib/ts/managers/Scenes.ts - removed load_from_text, changed new_scene return type, changed import_from_file to take callback

• di/src/lib/ts/managers/Versions.ts - added visible?: boolean to Portable_SO

• di/src/lib/svelte/details/D_Library.svelte - updated click handler and import button

• di/src/lib/svelte/details/Details.svelte - updated new-scene button

• di/notes/work/code.debt.md - checked off completed items

Current investigation into duplicate bug:

• propagate() (line 391) cascades through scene hierarchy - re-evaluates formulas that reference changed SOs

• propagate_all() (line 431) re-evaluates ALL formulas across all SOs

• The difference could cause issues if duplicate's per-clone propagation doesn't properly cascade

Summary:

1. Primary Request and Intent:

- User started by running /cd to read code.debt.md and work through unchecked items

- Checked off "table cell editing" items (already implemented)

- Main implementation task: "Load scenes without reloading" — extract scene loading into a reusable load_scene() method in Engine.ts, eliminate location.reload() from scene switching

- Added visible?: boolean to Portable_SO type (was a separate debt item)

- Currently investigating a duplicate bug: duplicate_selected() produces broken geometry (side/back panels wrong on the dup), while insert_child_from_text() (option-click) works perfectly. Refreshing fixes the issue.

2. Key Technical Concepts:

- Scene loading architecture: Engine.setup() has 3 phases — hardware init, scene rebuild, input wiring

- Portable_Scene / Portable_SO types define serialized scene format (JSON in .di files)

- Formula system: tokens (name-based refs like '', 'self', 'A') vs compiled AST (ID-based refs after bind_refs)

- constraints.rebind_formulas() resolves placeholder refs AND evaluates formulas immediately (line 317)

- constraints.propagate() cascades through hierarchy for a single changed SO

- constraints.propagate_all() re-evaluates ALL formulas across all SOs

- Constants must be restored BEFORE formula rebinding (evaluation needs them)

- hit_target Svelte action for custom mouse hit testing via RBush spatial index

3. Files and Code Sections:

- di/src/lib/ts/render/Engine.ts — Core file. Extracted load_scene() from setup().

- Added import: import type { Portable_Scene } from '../managers/Versions';

- setup() now calls this.load_scene(scenes.load()) instead of inline scene building

- New method load_scene(saved: Portable_Scene | null) handles teardown + rebuild + camera/selection restore

- duplicate_selected() (line 754+) — current bug investigation target

- insert_child_from_text() (line 530+) — works correctly, used as reference

- Key difference found: duplicate_selected calls constraints.propagate(clone) per-clone, while insert_child_from_text calls constraints.propagate_all() once

- The token remapping loop in duplicate_selected (lines 846-855) is effectively a no-op because tokens use NAMES while old_to_new maps IDs

- di/src/lib/ts/managers/Scenes.ts — Scene save/load manager

- Removed load_from_text() (had location.reload())

- new_scene() now returns Portable_Scene instead of void

- import_from_file(on_loaded: (scene: Portable_Scene) => void) takes callback instead of reloading

- parse_text() unchanged — parses JSON, validates, migrates

- di/src/lib/ts/managers/Versions.ts — Added visible?: boolean to Portable_SO interface

- di/src/lib/svelte/details/D_Library.svelte — Updated scene switching:

```typescript

function on_click(entry: LibEntry, e: MouseEvent): void {

if (e.altKey) {

engine.insert_child_from_text(entry.raw);

return;

}

const parsed = scenes.parse_text(entry.raw);

if (parsed) engine.load_scene(parsed);

}

```

Import button: scenes.import_from_file((s) => engine.load_scene(s))

- di/src/lib/svelte/details/Details.svelte — New-scene button: engine.load_scene(scenes.new_scene())

- di/src/lib/ts/algebra/Constraints.ts — Key methods under investigation:

- rebind_formulas() (line 302) — evaluates formulas immediately at line 317: attr.value = evaluator.evaluate(attr.compiled, (o, a) => this.resolve(o, a))

- propagate(changed_so) (line 391) — cascades through hierarchy, re-evaluates formulas referencing changed SOs

- propagate_all() (line 431) — re-evaluates ALL formulas across all SOs

- di/src/lib/ts/types/Attribute.ts — Formula serialization/deserialization:

- serialize(): if formula exists, returns { formula: tokenizer.untokenize(this.formula) }, else returns this.value

- deserialize(): tokenizes and compiles formula strings, sets this.value = 0 for formulas

- di/src/lib/ts/algebra/Tokenizer.ts — Token format for references:

- .l → { type: 'reference', object: '', attribute: 'l' } (empty string = parent)

- x → { type: 'reference', object: 'self', attribute: 'x' }

- A.x → { type: 'reference', object: 'A', attribute: 'x' } (SO name, NOT id)

- di/notes/work/code.debt.md — Checked off: table editing items, Portable_SO visible prop, load scenes without reloading

- di/src/lib/ts/runtime/Smart_Object.ts — serialize()/deserialize() already handle visible field

4. Errors and fixes:

- Portable_SO missing visible property: new_scene() in Scenes.ts set visible: false but the type didn't have the field. Fixed by adding visible?: boolean to Portable_SO in Versions.ts.

- Constants restored in wrong order: load_scene() initially restored constants AFTER deserialization and rebind_formulas. Since rebind_formulas evaluates formulas immediately (Constraints.ts line 317), constants were missing during evaluation. Fixed by moving constant restoration to BEFORE the deserialization loop.

- stretch.di appeared flat: After the constant ordering fix, user found the stretch.di FILE ITSELF was corrupted (y.length changed from { "formula": "template_w" } to bare 88.9). User fixed the file manually.

- Unused import warning for Portable_Scene: Expected during implementation, resolved when load_scene method was added.

5. Problem Solving:

- Completed: Load scenes without reloading — full implementation with load_scene() extraction, all callers updated, no more location.reload()

- Completed: Added visible to Portable_SO type

- Ongoing: Duplicate bug — duplicate_selected() produces broken geometry on cloned subtrees. Evidence: option-click insert works perfectly, duplicate doesn't. Refresh fixes it (so serialized state is correct, runtime state is wrong after duplicate).

- Key finding so far: duplicate_selected uses per-clone propagate(clone) while insert_child_from_text uses propagate_all(). The token ID remapping in duplicate is also a no-op (tokens use names, map uses IDs).

6. All user messages:

- /cd (invoked cd skill)

- "y" (approve exploring table cell editing code)

- "check em off" (check off the implemented table cell items)

- "new bug: dup creates 5 dups (four extra unwanted)"

- "i think my rootn so was corrupted. /cd"

- "no. read the next item" (when I proposed "new root -> invisible")

- "can setup call this new function?" (about load_scene extraction)

- "y" (approve implementation)

- "bug: rendered SO's look wrong (drawer, stretch -- is flat, room -- bloated clones, test, the drawer in wacka)"

- "stretch still loads flat as a sheet of paper"

- "ahah! i found the bug. i broke the stretch.di file. fixed it and stretch loads fine"

- Screenshot of duplicated drawer with broken geometry + "i created a new SO, loaded and selected drawer, then duplicated it. then dragged the original down and to the right to separate it from the dup. dup's side and back are wrong. refreshing fixed it"

- "yes, dig. i think it is a duplication bug. my evidence: i option clicked drawer and it showed up perfectly"

7. Pending Tasks:

- Investigate and fix the duplicate_selected() bug (geometry corruption on cloned subtrees)

- code.debt.md has many remaining unchecked items (parts position/size button, rotation work, library work, aesthetics, etc.)

8. Current Work:

Investigating the duplicate_selected() bug in Engine.ts. The user confirmed this is a duplication bug (not a load bug) with evidence: "i option clicked drawer and it showed up perfectly" while duplicating produces broken side/back panels. Refreshing fixes the issue.

I was comparing duplicate_selected() (Engine.ts ~line 774) vs insert_child_from_text() (Engine.ts ~line 495) and had just read propagate() (Constraints.ts line 391) and propagate_all() (line 431). Key difference identified:

- duplicate_selected calls constraints.propagate(clone) per-clone in a loop (line 859)

- insert_child_from_text calls constraints.propagate_all() once (line 601)

Also found that the token ID remapping loop in duplicate_selected (lines 846-855) is a no-op because attr.formula tokens use SO NAMES (like '', 'self', 'A'), not IDs, while old_to_new maps IDs to IDs.

9. Optional Next Step:

The likely fix is to replace the per-clone rebind_formulas + propagate(clone) loop in duplicate_selected() with the pattern used by insert_child_from_text(): call rebind_formulas for all clones first, then call constraints.propagate_all() once. The user explicitly asked to "dig" into this bug, and said "i think it is a duplication bug."

If you need specific details from before compaction (like exact code snippets, error messages, or content you generated), read the full transcript at: /Users/sand/.claude/projects/-Users-sand-GitHub-mono/64d7296d-fc70-4eb5-b275-723749da5d1c.jsonl

Please continue the conversation from where we left off without asking the user any further questions. Continue with the last task that you were asked to work on.

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