Implement the wide StateMachine condition workspace

[sfmskywalker]

Objective

Implement the wide condition authoring experience opened from ONLY IF, using the lossless adapter and ratified structured-clause boundary.

Context

• PRD: PRD: WF4-aligned StateMachine authoring and execution for Elsa 3.8 elsa-foundation#1456
• Current condition textarea is not acceptable normal UX.
• Existing ExpressionEditor can edit known provider expressions but Literal is intentionally handled separately.

Scope

• Modes for Always/missing, explicit true, Never/false, structured clauses where supported, provider expression, and custom definition.
• Wide dialog/drawer with clear summary and Apply/Cancel.
• No mutation before Apply.
• Advanced raw definition editor with validation and original-source preservation.
• Provider selector/editor reuse where safe.
• Read-only inspection mode.
• Responsive and keyboard behavior.

Non-goals

• Parsing arbitrary code into clauses.
• Normalizing unknown values.
• Treating Condition as an activity.

Architecture constraints

Use the pure adapter; apply through the wrapper/session mutation path; key provider editor state so transition/provider changes cannot leak stale Monaco content.

Dependencies

• Boolean-condition adapter.
• Structured-clause mapping spike.

Affected repositories

• elsa-workflows/elsa-studio

Acceptance criteria

• Cancel preserves the exact original condition.
• Always can preserve missing or explicitly clear to missing.
• Never is explicit and visibly warns that the transition cannot pass.
• Known provider expressions edit and save valid Boolean input JSON.
• Supported structured clauses round-trip losslessly.
• Unsupported/unknown definitions fall back without data loss.
• Invalid advanced JSON cannot be applied.
• Read-only, keyboard, and narrow viewport states pass.

Validation

Adapter and bUnit tests, provider integration test, save/reload round-trip, and browser verification.

Agent readiness

Not Ready — depends on the adapter and structured-clause spike.

[sfmskywalker]

#955 resolved the structured boundary: no current provider exposes a lossless clause AST, so this task must not invent or heuristically parse structured JSON. Acceptance clarification: render structured mode only for a future explicitly capable provider; preserve existing provider type/value opaquely; make Apply the first mutation point; warn/disable lossy mode switches; keep unknown/unavailable/malformed values in exact-preserving Custom mode; invalid Custom source cannot apply; read-only disables every mutation path.

[sfmskywalker]

Claimed on branch codex/state-machine-transition-authoring after #954 and #955 completion. Implementing the wide transactional condition workspace using the lossless adapter: Always, Never, provider-native Expression, and exact-preserving Custom modes; structured clauses remain capability-gated.

[sfmskywalker]

Implemented in 402168f1. ONLY IF now opens a wide transactional workspace for Always, explicit Never, known provider expressions, and validated Custom JSON. Unknown values remain lossless, lossy switches are explicitly warned, and explicit true is preserved unless the user deliberately clears it. Validation: focused bUnit coverage plus full Workflows suite (100/100).