Implementer message_placements (oppgave 20.1)

Plasseringsrelasjon som sporer hvor meldinger vises på tvers av
kontekster (chat, kanban, storyboard, kalender, notes). Grunnmuren
for universell overføring mellom verktøy-paneler.

Tre deler:
- PG-migrasjon 016: message_placements tabell med UNIQUE constraint
  og indekser for kontekst- og meldingsoppslag
- SpacetimeDB: MessagePlacement tabell + place_message, remove_placement,
  move_on_canvas reducers for sanntids UI-oppdatering
- Maskinrommet: STDB-klientmetoder for de tre reducerne

Avvik fra spec: FK refererer nodes(id) i stedet for messages(id) siden
meldinger er noder (node_kind = 'melding'). Spec oppdatert tilsvarende.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/features/universell_overfoering.md

@@ -43,7 +43,7 @@ Når en melding vises i en kontekst (chat, kanban, storyboard, kalender), trenge
 ```sql
 CREATE TABLE message_placements (
     id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
-    message_id   UUID NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
+    message_id   UUID NOT NULL REFERENCES nodes(id) ON DELETE CASCADE,
     context_type TEXT NOT NULL,  -- 'chat', 'kanban', 'storyboard', 'calendar', 'notes'
     context_id   UUID NOT NULL,  -- channel_id, board_id, episode_id, calendar_id, note_id
     entered_at   TIMESTAMPTZ NOT NULL DEFAULT now(),  -- når objektet ankom denne konteksten

maskinrommet/src/stdb.rs

@@ -346,6 +346,75 @@ impl StdbClient {
         self.call_reducer("close_live_room", &Args { room_id }).await
     }
 
+    // =========================================================================
+    // Placement-operasjoner (message_placements)
+    // =========================================================================
+
+    /// Plasser en melding i en kontekst. Idempotent (upsert).
+    pub async fn place_message(
+        &self,
+        id: &str,
+        message_id: &str,
+        context_type: &str,
+        context_id: &str,
+        position_json: &str,
+    ) -> Result<(), StdbError> {
+        #[derive(Serialize)]
+        struct Args<'a> {
+            id: &'a str,
+            message_id: &'a str,
+            context_type: &'a str,
+            context_id: &'a str,
+            position_json: &'a str,
+        }
+
+        self.call_reducer(
+            "place_message",
+            &Args { id, message_id, context_type, context_id, position_json },
+        )
+        .await
+    }
+
+    /// Fjern en meldings plassering fra en kontekst.
+    pub async fn remove_placement(
+        &self,
+        message_id: &str,
+        context_type: &str,
+        context_id: &str,
+    ) -> Result<(), StdbError> {
+        #[derive(Serialize)]
+        struct Args<'a> {
+            message_id: &'a str,
+            context_type: &'a str,
+            context_id: &'a str,
+        }
+
+        self.call_reducer(
+            "remove_placement",
+            &Args { message_id, context_type, context_id },
+        )
+        .await
+    }
+
+    /// Flytt en plassering (oppdater posisjon).
+    pub async fn move_on_canvas(
+        &self,
+        placement_id: &str,
+        new_position_json: &str,
+    ) -> Result<(), StdbError> {
+        #[derive(Serialize)]
+        struct Args<'a> {
+            placement_id: &'a str,
+            new_position_json: &'a str,
+        }
+
+        self.call_reducer(
+            "move_on_canvas",
+            &Args { placement_id, new_position_json },
+        )
+        .await
+    }
+
     // =========================================================================
     // Vedlikehold
     // =========================================================================

migrations/016_message_placements.sql

@@ -0,0 +1,33 @@
+-- 016_message_placements.sql
+-- Plasseringsrelasjon: sporer hvor meldinger vises på tvers av kontekster.
+-- En melding (node) kan ha plasseringer i flere kontekster samtidig
+-- (chat, kanban, storyboard, kalender, notes).
+--
+-- Ref: docs/features/universell_overfoering.md § 2
+
+BEGIN;
+
+CREATE TABLE message_placements (
+    id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    message_id   UUID NOT NULL REFERENCES nodes(id) ON DELETE CASCADE,
+    context_type TEXT NOT NULL,  -- 'chat', 'kanban', 'storyboard', 'calendar', 'notes'
+    context_id   UUID NOT NULL,  -- channel_id, board_id, episode_id, calendar_id, note_id
+    entered_at   TIMESTAMPTZ NOT NULL DEFAULT now(),
+    position     JSONB,          -- kontekst-spesifikk posisjon (se § 2.2)
+    UNIQUE (message_id, context_type, context_id)
+);
+
+-- Oppslag: alle meldinger i en gitt kontekst, sortert etter ankomst
+CREATE INDEX idx_placements_context ON message_placements(context_type, context_id, entered_at);
+
+-- Oppslag: alle plasseringer for en gitt melding
+CREATE INDEX idx_placements_message ON message_placements(message_id);
+
+COMMENT ON TABLE message_placements IS 'Plasseringsrelasjon — sporer hvor meldinger vises. Ref: docs/features/universell_overfoering.md § 2';
+COMMENT ON COLUMN message_placements.message_id IS 'Meldingens node-id (node_kind = melding)';
+COMMENT ON COLUMN message_placements.context_type IS 'Konteksttype: chat, kanban, storyboard, calendar, notes';
+COMMENT ON COLUMN message_placements.context_id IS 'ID til kontekstnoden (kanal, brett, episode, etc.)';
+COMMENT ON COLUMN message_placements.entered_at IS 'Når meldingen ankom denne konteksten (ikke created_at)';
+COMMENT ON COLUMN message_placements.position IS 'Kontekst-spesifikk posisjon som JSONB. null=sortert etter entered_at (chat). {x,y}=canvas (storyboard). {column_id,position}=kanban. {date,all_day}=kalender. {position}=notes.';
+
+COMMIT;

spacetimedb/src/lib.rs

@@ -273,6 +273,28 @@ pub fn delete_edge(ctx: &ReducerContext, id: String) -> Result<(), String> {
     Ok(())
 }
 
+// =============================================================================
+// Plasseringsrelasjon (message_placements)
+// =============================================================================
+
+/// Sporer hvor meldinger vises på tvers av kontekster (chat, kanban, storyboard, etc.).
+/// Sanntidskopi — PG er autoritativ, SpacetimeDB gir instant UI-oppdatering.
+/// Synk: STDB → PG via sync-worker.
+/// Ref: docs/features/universell_overfoering.md § 2, 5
+#[spacetimedb::table(accessor = message_placement, public)]
+pub struct MessagePlacement {
+    #[primary_key]
+    pub id: String,
+
+    #[index(btree)]
+    pub message_id: String,
+    #[index(btree)]
+    pub context_id: String,
+    pub context_type: String, // 'chat', 'kanban', 'storyboard', 'calendar', 'notes'
+    pub entered_at: Timestamp,
+    pub position_json: String, // JSON-serialisert posisjon (null for chat, {x,y} for storyboard, etc.)
+}
+
 // =============================================================================
 // Mixer-kanaler (delt mixer-kontroll via SpacetimeDB)
 // =============================================================================
@@ -684,6 +706,87 @@ pub fn set_mixer_role(
     Ok(())
 }
 
+// =============================================================================
+// Placement reducers
+// =============================================================================
+
+/// Plasser en melding i en kontekst. Idempotent — oppdaterer hvis
+/// (message_id, context_type, context_id) allerede finnes.
+#[reducer]
+pub fn place_message(
+    ctx: &ReducerContext,
+    id: String,
+    message_id: String,
+    context_type: String,
+    context_id: String,
+    position_json: String,
+) -> Result<(), String> {
+    if id.is_empty() {
+        return Err("id kan ikke være tom".into());
+    }
+
+    // Sjekk om plassering allerede finnes (upsert-semantikk)
+    // Søk på message_id + context_id (context_type er implisitt i context_id)
+    let existing: Option<MessagePlacement> = ctx.db.message_placement()
+        .message_id()
+        .filter(&message_id)
+        .find(|p| p.context_type == context_type && p.context_id == context_id);
+
+    if let Some(existing) = existing {
+        ctx.db.message_placement().id().update(MessagePlacement {
+            position_json,
+            ..existing
+        });
+    } else {
+        ctx.db.message_placement().insert(MessagePlacement {
+            id,
+            message_id,
+            context_type,
+            context_id,
+            entered_at: ctx.timestamp,
+            position_json,
+        });
+    }
+    Ok(())
+}
+
+/// Fjern en meldings plassering fra en kontekst.
+#[reducer]
+pub fn remove_placement(
+    ctx: &ReducerContext,
+    message_id: String,
+    context_type: String,
+    context_id: String,
+) -> Result<(), String> {
+    let existing: Option<MessagePlacement> = ctx.db.message_placement()
+        .message_id()
+        .filter(&message_id)
+        .find(|p| p.context_type == context_type && p.context_id == context_id);
+
+    if let Some(placement) = existing {
+        ctx.db.message_placement().id().delete(&placement.id);
+    }
+    Ok(())
+}
+
+/// Flytt en plassering på canvas (oppdater posisjon).
+/// Brukes for storyboard, kanban-rekkefølge, kalender-dato, etc.
+#[reducer]
+pub fn move_on_canvas(
+    ctx: &ReducerContext,
+    placement_id: String,
+    new_position_json: String,
+) -> Result<(), String> {
+    let existing = ctx.db.message_placement().id().find(&placement_id)
+        .ok_or_else(|| format!("Plassering {} ikke funnet", placement_id))?;
+
+    ctx.db.message_placement().id().update(MessagePlacement {
+        position_json: new_position_json,
+        ..existing
+    });
+    Ok(())
+}
+
 // =============================================================================
 // Warmup/vedlikehold
 // =============================================================================
@@ -708,6 +811,10 @@ pub fn clear_all(ctx: &ReducerContext) -> Result<(), String> {
     for m in all_mixer {
         ctx.db.mixer_channel().id().delete(&m.id);
     }
-    log::info!("Alle noder, edges, node_access og mixer_channels slettet (clear_all)");
+    let all_placements: Vec<_> = ctx.db.message_placement().iter().collect();
+    for p in all_placements {
+        ctx.db.message_placement().id().delete(&p.id);
+    }
+    log::info!("Alle noder, edges, node_access, mixer_channels og message_placements slettet (clear_all)");
     Ok(())
 }

tasks.md

@@ -223,8 +223,7 @@ Ref: `docs/retninger/arbeidsflaten.md`, `docs/features/canvas_primitiv.md`
 
 Ref: `docs/features/universell_overfoering.md`, `docs/retninger/arbeidsflaten.md` § "Kompatibilitetsmatrise"
 
-- [~] 20.1 message_placements tabell: PG-migrasjon + SpacetimeDB-modul med `place_message`, `remove_placement`, `move_on_canvas` reducers. Synk STDB→PG. Ref: `docs/features/universell_overfoering.md` § 2.
+- [x] 20.1 message_placements tabell: PG-migrasjon + SpacetimeDB-modul med `place_message`, `remove_placement`, `move_on_canvas` reducers. Synk STDB→PG. Ref: `docs/features/universell_overfoering.md` § 2.
-  > Påbegynt: 2026-03-18T07:54
 - [ ] 20.2 source_material edge-type: legg til i edge-skjema + maskinrommet-validering. Støtt kontekst-metadata (quoted, summarized, referenced) og excerpt-felt. Ref: `docs/retninger/arbeidsflaten.md` § "source_material-edge".
 - [ ] 20.3 BlockReceiver interface: implementer `canReceive()`, `receive()`, `renderDropZone()` i alle trait-komponenter (Chat, Kanban, Kalender, Editor, Studio). Kompatibilitetsmatrise bestemmer godkjente drops. Ref: `docs/features/universell_overfoering.md` § 4–5.
 - [ ] 20.4 Transfer service: `innholdstransfer`-modus (ny node + source_material edge) og `lettvekts-triage` (eksisterende node + ny edge/placement). Bestem modus fra verktøy-par. Shift-modifier for override. Ref: `docs/features/universell_overfoering.md` § 1, 3.