Building one stage

A stage is one classroom: one settled plan, one roster, one deck of pages. This is how a stage is built here, whatever its subject.

A topic skill (deep-interactive, vocational, deep-research, teacher-style-clone, …) may shape what the stage contains — its structure, its page types, how scenes are named — and where one is active its instructions win on those questions. The sequence below is not one of those questions: it is the same under every topic skill. Read this one first, then the topic skill.

Nothing here applies to a stage that already has pages. A stage with persisted pages is edited, not built (see pro-editing).

The build sequence

Build a NEW stage only when there are no persisted pages yet. Then, in this order:

1. Plan the stage in the conversation. Propose the page plan yourself — each page with its title, type (slide / quiz / interactive / pbl) and brief (this page's teaching intent and content outline, the same information a planned outline slot used to carry) — in page order. Settle the plan with the user through ask_user before creating anything: there is no outline tool to plan with, so the plan is your words and their sign-off. Skip that confirmation round when the user already gave a complete page structure or explicitly asked you to go ahead directly — their message is the sign-off. A topic skill's structural constraints are a diagnostic the runtime checks against the real stage after each page; you decide how to act on it.
2. create_stage with the settled course title (pass the series folder's folderId when the stage is part of a series, so it is filed in the same call). From here on, pass the returned stageId to every stage tool.
3. set_roster, before any page is generated. Write the classroom the user settled: exactly one teacher, at least two agents in total, each with a concrete persona (2-3 sentences on personality and teaching/learning style, in the stage language) and a voice — call list_voices first and bind one of the returned providerId::voiceId pairs, or the exact pair register_voice returned for a cloned voice; omit the binding when no usable voice exists. Every page's content and narration is written for the roster that exists when the page is generated, so a roster settled late is a roster half the stage never saw.
4. generate_scene for EACH settled page, in ascending order — one page per call, never more. Pass the page's settled title, type and brief (plus materialFacts when the page's content comes from attached material); no planned outline is needed. A pbl page is generated the same way and lands as a full PBL project (projectV2) from its brief; a failed generation reports an error and writes nothing. Each call is the durable checkpoint for its page: the page survives an interruption only once the call has returned. As soon as a page's generate_scene succeeds, call generate_tts on that page, then go on to the next page.
5. list_scenes to verify every page you settled is actually persisted.

None of the planning steps is a place to stop: a turn ends when a page actually landed, when ask_user is waiting on the user, or when the stage is done by the check below. Reporting what you have planned, imported or confirmed leaves the user holding an empty deck.

When generate_scene fails

Track generation attempts by stageId + order. Changing the title or brief, or generating another page in between, does not reset the attempt.

• For prompt-unavailable or another deterministic failure, do not repeat the same call.
• For invalid-model-output, change the brief without changing the settled teaching intent, then retry once. Retry once for a clearly transient provider failure too.
• If that retry fails, do not call generate_scene again for that target during this run. Leave the page unwritten, continue with later pages in the same stage, and name the gap when wrapping up. Do not call ask_user after every failed page or silently drop the page from the settled plan.

Use list_scenes to reconcile persisted pages with the settled plan. A stage with a missing page can be wrapped up after later pages are built, but it is not done; name each gap and its latest failure instead of claiming completion.

Narration audio follows narration text

When a page's narration is written or reworded with patch_stage on an /actions/... JSON Pointer, call generate_tts on that page. A reworded speech line has no audio until the page is re-synthesized, so narration text that was changed and not re-synthesized ships as a silent page.

Before you call the stage done

Every settled page has to be persisted — a stage is done when the deck is complete, not when it is planned or half built.

Every speech action must have audio. Call generate_tts once on each page in its default mode: it fills only the lines missing audio and reports how many were generated, skipped, or failed, so there is no need to read each page's source to check audioId. Re-run it only where it reported failures or where narration wording changed afterwards. Then read each page's actions once with read_stage at path:/scenes/<order|id>/actions, detail:"source", following nextOffset until it is exhausted — only the actions subtree, not the whole page. A speech action with blank text is a defect (TTS skips it silently), and so is narration that talks about material this stage does not teach, whatever its audio status. Only then is the stage finished.

Close with a brief report: what was built, any gap left, and anything that needs the user's decision.