v18: the flow designer and simulator stop teaching and emulating the single-brace {var} dialect, which objectstack#19939 deletes (the objectui half of #19939 pass 4, S7) #12329

Blocked-by: objectstack-ai/objectstack#19939

Filing gate: cross-repo rule 3. An accepted objectstack PR's product flows into this repo, and the accepting seat files the consumer's follow-up. The stage plan 6096263424 on objectstack-ai/objectstack#19939 names this as "a companion card in objectui, filed by this seat at each stage's ACCEPT". This one is S7's, the close-out. objectui#12101 is S1's.

Filed by objectstack domain:spec seat 2 (objectstack-ai/objectstack#18549) · os-justin · session session_01BRQ9Mp1yH7R1az6MaUM18H. ⛔ Not a claim. Reader who acts: objectui triage, to route it. The sites are in packages/app-shell.

Unlock: objectstack-ai/objectstack#19939 closes when PR objectstack-ai/objectstack#23252 merges. Then, by the cross-repo unlock rule, this card moves to pm:on-hold with an install-surface Restart-when: (a @objectstack/spec@next release built from that merge). It is dispatched only once objectui resolves that release.

What changes upstream (PR objectstack-ai/objectstack#23252)

• The single-brace interpolator in @objectstack/service-automation is deleted. Every flow position S1–S6 retired already refuses a {var} token at registration, and the last two literal callers pass values as written.
• Every flow condition is CEL. A braced string is refused as the brace trap, and a template or flow envelope is refused too.
• @objectstack/lint reads no single-brace token, and its grammar mirror's four exports are removed. objectui's pin 1fb1ced36 imports none of them.

The sites here, measured by the S7 dev at objectui ee470719

• packages/app-shell/src/views/metadata-admin/inspectors/flow-node-config.ts:
  • :690 and :706: collection placeholders '{leadList}' / '{items}' with refMode: 'template';
  • :350 and :361: help text calling a collection an interpolate() template;
  • :589 and :816: descriptions saying "interpolates {var}".
• inspectors/json-schema-to-fields.ts:102, :259 and :295: xExpression: 'template' mapped to a single-brace picker.
• previews/simulator/flow-simulator.ts:455–:581: its own interpolateValue / interpolateString, modelled on the deleted runtime interpolator. The simulator would show a run the engine refuses.

Acceptance

Run on the installed release:

• No designer site offers, prescribes or describes a {var} token. A value position authors the CEL value envelope, and a text position authors {{ }}, as objectui#12101 and objectui#11824 do for theirs.
• The simulator evaluates what the engine evaluates. Either it drops its own interpolator or it refuses what the engine refuses, with a pin per position.

Dedupe

MCP search_issues on objectstack-ai/objectui, closed included:

• objectstack#19939 single-brace dialect retired designer companion value slot CEL envelope picker → 8 hits. objectui#12101 (S1's companion, the subflow and script inputs) and objectui#11824 (#22110's text slots) are siblings for other positions. None is these sites.
• flow designer single-brace picker template refMode simulator interpolate flow-node-config → 10 hits, all closed and about other designer questions.

Dedupe words: flow designer single-brace placeholder; refMode template collection; flow-simulator interpolateValue; xExpression template picker.

Generated by Claude Code