begin: surface forced cells in the UI

[sean-parent]

Summary

• Query property_model::Sheet::is_forced/forced_cells() (already implemented in property-model) after every propagate() in the begin demo app.
• Disable the Inspector's text field for any cell that's currently forced — its value is always overwritten by an active relationship regardless of what's typed.
• Highlight forced cells and every constraint edge touching one (both the edge that produces the cell and any outgoing edges carrying its value onward) in the D3 graph, in a distinct purple.
• Extend the demo source (DEMO_SOURCE) with a new cell g forced by a single-method relationship, gated on the existing p conditional — toggling p between 0 and 1 toggles g between editable and forced/disabled/highlighted.

Notable implementation detail

g's forcing relationship is declared in its own conditional p { 1i32 => { .. } } block rather than folded into the existing 1i32 branch. pm-lang groups every method in one branch into a single relationship, and a relationship's forced outputs are the intersection of its methods' pure outputs — mixing [c] -> [g] in with the existing c/f methods would make that intersection empty, forcing nothing. Two conditionals sharing the same match cell compose independently, so this is a distinct relationship gated on the same p == 1 condition (this also means the graph now renders two diamond nodes for p). See the doc comment on DEMO_SOURCE in begin/src/app.rs and the design spec's superseded-approach note for the full reasoning.

Test plan

• cargo build --workspace — zero warnings
• cargo test --workspace / cargo test --doc --workspace — all passing
• cargo clippy --workspace --exclude begin -- -D warnings — clean
• cargo clippy -p begin --no-default-features -- -D warnings — clean
• New unit tests: bridge.rs (GraphData::forced populated/excluded by conditional branch activity), app.rs (g forced/unforced across p toggling, including round-trip back to unforced)
• Manual: dx serve --platform desktop, toggle p between 0 and 1, confirm g's Inspector field disables/enables and the graph highlights g plus its edges accordingly — not yet run in this environment (no GUI available); recommend a quick pass before merging

Design spec: docs/superpowers/specs/2026-07-09-begin-forced-cells-ui-design.md
Implementation plan: docs/superpowers/plans/2026-07-09-begin-forced-cells-ui.md

🤖 Generated with Claude Code

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Note

Low Risk
Demo/UI-only changes in begin using existing property-model APIs; no auth, persistence, or core solver changes.

Overview
The begin demo now surfaces forced cells from Sheet::is_forced / forced_cells: values that an active relationship will always overwrite on propagate(), so editing them in the UI was misleading.

Bridge → D3: GraphData gains a forced list of stable cell node IDs (same pattern as changed). graph.js applies forced / forced-edge classes so those cells and any constraint edge touching them (incoming or outgoing) render in purple.

Inspector: CellRow disables SpTextfield when the cell is forced; SpTextfield adds a disabled prop on <sp-textfield>.

Demo: DEMO_SOURCE adds cell g and a second conditional p { 1i32 => … } with g = c * 10 so forcing works as a single-method relationship (documented in the DEMO_SOURCE comment). Tests in app.rs and bridge.rs cover forced state vs conditional branch activity.

Design/plan docs under docs/superpowers/ were added for this work.

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[Copilot]

Pull request overview

Surfaces forced cells (as reported by property_model::Sheet::{is_forced, forced_cells}) in the begin demo app so users can see which cell values will be overwritten by active relationships and avoid editing values that cannot “stick”.

Changes:

• Add GraphData::forced and populate it from Sheet::forced_cells() so the graph UI can style forced cells/edges.
• Disable the Inspector textfield when Sheet::is_forced(id) is true.
• Extend the demo pm-lang source with a conditionally-forced cell g and add unit tests covering forced/unforced transitions.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
docs/superpowers/specs/2026-07-09-begin-forced-cells-ui-design.md	Design spec for forced-cell Inspector/graph behavior and demo source changes.
docs/superpowers/plans/2026-07-09-begin-forced-cells-ui.md	Implementation plan describing how to plumb forced-cell state into UI + demo source.
begin/src/spectrum.rs	Add disabled: bool prop to SpTextfield and map it to <sp-textfield disabled>.
begin/src/inspector.rs	Compute forced per cell and disable the Inspector input for forced cells.
begin/src/bridge.rs	Add GraphData::forced and tests verifying it tracks active conditional forcing.
begin/src/app.rs	Update DEMO_SOURCE to include conditionally forced cell g, plus tests for g forced/unforced across p toggles.
begin/assets/graph.js	Highlight forced cell nodes and any constraint edge touching a forced cell.
begin/assets/graph.css	Add purple styling for forced cells (.node-cell.forced) and forced edges (.link.forced-edge).

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