Storylines: the same site told several ways, one per visitor, counted

Any text a person reads may be a list, one entry per storyline, every
list the same length. A visitor is given one storyline for the whole
site and reads it on every page and in every mail about their case.
Records and events carry the storyline; GET /report gives counts per
bucket, storyline and state, and nothing else.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

src/app.rs

@@ -2358,8 +2358,9 @@ pub async fn get_question(
     use crate::content::{fill_from_user, path_matches, resolve_question};
     use crate::server::AppState;
     let state = expect_context::<AppState>();
-    let questions = state.questions.load();
-    let Some(mut question) = resolve_question(&questions, &path) else {
+    let storylines = state.questions.load();
+    let questions = storylines.at(crate::server::storyline::current().await);
+    let Some(mut question) = resolve_question(questions, &path) else {
         return Ok(None);
     };
     let session: tower_sessions::Session = leptos_axum::extract().await?;
@@ -2401,7 +2402,7 @@ pub async fn get_question(
 pub async fn get_site() -> Result<SiteConfig, ServerFnError> {
     use crate::server::AppState;
     let state = expect_context::<AppState>();
-    let mut site = state.site.load().as_ref().clone();
+    let mut site = state.site.load().at(crate::server::storyline::current().await).clone();
     // Not content: whether this instance can serve tiles at all is its
     // own configuration, and the browser has to know before it decides
     // whether to draw a map or ask for two numbers.
@@ -2435,7 +2436,8 @@ pub async fn list_qualifying_questions(
         .map_err(|e| ServerFnError::new(e.to_string()))?;
 
     let now_ms = chrono::Utc::now().timestamp_millis();
-    let questions = state.questions.load();
+    let storylines = state.questions.load();
+    let questions = storylines.at(crate::server::storyline::current().await);
     // What the chain verifiably answered - the same lookup a
     // `requires_chain` gate does, so a forged or foreign hash resolves
     // to nothing - and therefore where it sent the visitor.
@@ -2583,6 +2585,7 @@ pub async fn suggest_page_edit(question_id: String, text: String) -> Result<(),
         SUGGESTION_ALTERNATIVE,
         &responses,
         now_ms,
+        0,
     )
     .await
     .map_err(|e| ServerFnError::new(e.to_string()))?;
@@ -2593,6 +2596,7 @@ pub async fn suggest_page_edit(question_id: String, text: String) -> Result<(),
         alternative: SUGGESTION_ALTERNATIVE.to_string(),
         responses: responses.clone(),
         timestamp_ms: now_ms,
+        storyline: 0,
     };
     if let Err(e) = emit_answer_submitted(&state.nats, &event).await {
         tracing::warn!(question_id, "the suggestion is on file but was not announced: {e}");
@@ -2679,7 +2683,8 @@ pub async fn submit_answer(
     // resolve_question, not a plain map get: a dynamic page's concrete
     // path (what the client holds as its question id) resolves to the
     // pattern page it came from.
-    let question = crate::content::resolve_question(&state.questions.load(), &question_id)
+    let storyline = crate::server::storyline::current().await;
+    let question = crate::content::resolve_question(state.questions.load().at(storyline), &question_id)
         .ok_or_else(|| ServerFnError::new("unknown question"))?;
 
     let session: tower_sessions::Session = leptos_axum::extract().await?;
@@ -2796,6 +2801,7 @@ pub async fn submit_answer(
             alternative: alternative.clone(),
             responses: responses.clone(),
             timestamp_ms,
+            storyline: storyline as u32,
         },
     )
     .await
@@ -2821,6 +2827,7 @@ pub async fn submit_answer(
             &alternative,
             &responses,
             timestamp_ms,
+            storyline as u32,
         )
         .await
         {
@@ -2829,7 +2836,7 @@ pub async fn submit_answer(
         // Arrival is a state too: what the schema says the first
         // state sends, it sends now.
         if let Some(initial) = state.aggregates.load().get(bucket).map(|s| s.initial.clone()) {
-            crate::mail::on_state(&state, bucket, &chain_hash, &initial, &responses).await;
+            crate::mail::on_state(&state, bucket, &chain_hash, &initial, &responses, storyline as u32).await;
             crate::people::on_state(&state, bucket, &chain_hash, &initial, &responses).await;
         }
     }