fix(persona-chat): review fixes before merge

- Thread tools are bound server-side to the chat's own thread. The model
  used to pass contact_id, so practice mode could read any conversation it
  named; a model-supplied contact_id is now only checked, never trusted, and
  the prompts no longer hand it one.
- Practice chats need no persona. They're stored under PRACTICE_PERSONA_ID
  and run with an inert stand-in, so deleting or editing personas can't hide
  or break them. persona_id is optional on create for as_contact.
- The per-thread list filters in SQL (list_persona_chats_for_contact, served
  by idx_persona_chat_anchor_contact) instead of decoding every transcript.
- fetch_mms_image checks the content type and a 20 MB cap before reading
  the body, so a video attachment isn't downloaded in full.
- get_photos_near_time unions tags over every path sharing the content, per
  the multi-library model.
- look_at_photo only opens indexed photos, so an excluded folder can't be
  read by guessing a path.
- One date parser: get_photos_near_time uses date_info::parse_center.
- Practice prompt source rewrapped.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -578,13 +578,19 @@ GET  /insights/chat/history?path=... (rendered transcript with tool invocations)
 POST /insights/chat/rewind           (truncate transcript at a rendered index)
 
 // Persona chat — "Continue with persona" from an SMS thread (src/ai/sms_anchor.rs)
-POST /persona_chat/conversations     (body: { persona_id, anchor?: { contact_id, message_id } };
+POST /persona_chat/conversations     (body: { persona_id, anchor?: { contact_id, message_id,
-                                      anchor snapshots ~40 SMS-API messages up to message_id into
+                                      mode?: "about" | "as_contact" } }; anchor snapshots ~40
-                                      the row, 502 if SMS-API can't read the thread)
+                                      SMS-API messages up to message_id into the row, 502 if
-GET  /persona_chat/conversations?contact_id=N   (only chats anchored on that thread)
+                                      SMS-API can't read the thread. `as_contact` (practice) needs
-//   Anchored turns append the thread + chat-register guidance to the persona prompt and add
+                                      no persona: stored under PRACTICE_PERSONA_ID, listed as
-//   the get_thread_messages / look_at_message_image / get_photos_near_time / look_at_photo
+                                      "Practice")
-//   tools (ToolGateOpts.sms_thread_tools). Image tools use the LOCAL vision model.
+GET  /persona_chat/conversations?contact_id=N   (only chats anchored on that thread; DAO query)
+//   Anchored turns append the thread + mode guidance to the prompt and add the thread
+//   tools (ToolGateOpts.sms_thread_tools): get_thread_messages / look_at_message_image are
+//   bound server-side to the chat's own thread (a model-named contact_id is refused), and
+//   about-mode also gets get_photos_near_time / look_at_photo. Practice keeps only the two
+//   thread tools. Image tools use the LOCAL vision model; MMS downloads are image-only and
+//   capped (MMS_IMAGE_MAX_BYTES); look_at_photo only opens indexed photos.
 
 // User AI Prefs (owner defaults + passive mirror; src/prefs.rs)
 GET  /prefs                          (current row; auth)

src/ai/date_info.rs

@@ -10,7 +10,7 @@
 //! Everything is computed in the owner's display zone, so the dates match
 //! the timestamps the model reads in thread transcripts and photo metadata.
 
-use chrono::{DateTime, Datelike, Months, NaiveDate, NaiveDateTime, Utc};
+use chrono::{DateTime, Datelike, Months, NaiveDate, NaiveDateTime, TimeZone, Utc};
 use chrono_tz::Tz;
 
 /// A date argument as the model gave it. A bare date stays a date (no
@@ -63,6 +63,19 @@ fn parse_moment(value: &serde_json::Value, zone: Tz) -> Option<Moment> {
         .map(Moment::Day)
 }
 
+/// A moment for tools that search *around* a time (`get_photos_near_time`),
+/// as unix seconds. Same formats as `date_info`; a bare date centres on
+/// local midday, the least-wrong centre for a whole day.
+pub fn parse_center(value: &serde_json::Value, zone: Tz) -> Option<i64> {
+    let local = match parse_moment(value, zone)? {
+        Moment::At(dt) => dt,
+        Moment::Day(d) => d.and_hms_opt(12, 0, 0)?,
+    };
+    zone.from_local_datetime(&local)
+        .earliest()
+        .map(|dt| dt.timestamp())
+}
+
 /// Whole years, months and days from `a` to `b` (`a <= b`), counted the
 /// calendar way: Jan 31 + 1 month is Feb 28/29, as people count ages.
 fn calendar_gap(a: NaiveDate, b: NaiveDate) -> (u32, u32, u32) {
@@ -227,7 +240,6 @@ pub fn date_info(args: &serde_json::Value, now: DateTime<Utc>, zone: Tz) -> Stri
 #[cfg(test)]
 mod tests {
     use super::*;
-    use chrono::TimeZone;
     use serde_json::json;
 
     const NY: Tz = chrono_tz::America::New_York;
@@ -339,6 +351,19 @@ mod tests {
         assert_eq!(describe_gap(d(2025, 10, 18), d(2026, 10, 18)), "1 year");
     }
 
+    #[test]
+    fn parse_center_reads_unix_wall_clock_and_bare_dates() {
+        assert_eq!(parse_center(&json!(1_700_000_000), NY), Some(1_700_000_000));
+        // 2023-11-14 17:13 in New York (EST) = 22:13 UTC.
+        assert_eq!(
+            parse_center(&json!("2023-11-14 17:13"), NY),
+            Some(1_699_999_980)
+        );
+        // A bare date centres on local midday.
+        assert_eq!(parse_center(&json!("2023-11-14"), NY), Some(1_699_981_200));
+        assert_eq!(parse_center(&json!("soon"), NY), None);
+    }
+
     #[test]
     fn bad_input_says_what_format_to_use() {
         let out = date_info(&json!({"date": "last tuesday"}), now(), NY);

src/ai/insight_chat.rs

@@ -473,6 +473,7 @@ impl InsightChatService {
                             &normalized,
                             req.user_id,
                             &active_persona,
+                            None,
                         )
                         .instrument(loop_span.clone())
                         .await;
@@ -1435,6 +1436,7 @@ impl InsightChatService {
             normalized,
             user_id,
             active_persona,
+            None,
             max_iterations,
             entry,
             fitter,
@@ -1990,6 +1992,7 @@ impl InsightChatService {
                             normalized,
                             user_id,
                             active_persona,
+                            None,
                         )
                         .await;
                     let (result_preview, result_truncated) = truncate_tool_result(&result);
@@ -2624,6 +2627,7 @@ pub async fn run_streaming_agentic_loop_with_entry(
     normalized: &str,
     user_id: i32,
     active_persona: &str,
+    thread_contact: Option<i64>,
     max_iterations: usize,
     entry: &Arc<TurnEntry>,
     fitter: &mut ContextFitter,
@@ -2720,6 +2724,7 @@ pub async fn run_streaming_agentic_loop_with_entry(
                             normalized,
                             user_id,
                             active_persona,
+                            thread_contact,
                         )
                         .await
                 } else {

src/ai/insight_generator.rs

@@ -1891,6 +1891,7 @@ Return ONLY the summary, nothing else."#,
         file_path: &str,
         user_id: i32,
         persona_id: &str,
+        thread_contact: Option<i64>,
     ) -> String {
         let model = backend.model();
         let backend_label = backend.kind.as_str();
@@ -1940,9 +1941,12 @@ Return ONLY the summary, nothing else."#,
             "date_info" => {
                 crate::ai::date_info::date_info(arguments, Utc::now(), self.display_zone())
             }
-            "get_thread_messages" => self.tool_get_thread_messages(arguments).await,
+            "get_thread_messages" => {
+                self.tool_get_thread_messages(arguments, thread_contact)
+                    .await
+            }
             "look_at_message_image" => {
-                self.tool_look_at_message_image(arguments, backend.local())
+                self.tool_look_at_message_image(arguments, thread_contact, backend.local())
                     .await
             }
             "get_photos_near_time" => self.tool_get_photos_near_time(arguments).await,
@@ -2411,9 +2415,14 @@ Return ONLY the summary, nothing else."#,
     /// Tool: get_thread_messages — page the anchored SMS thread from a
     /// message id. Lines are rendered exactly like the anchor snapshot so
     /// the model can keep paging from any id it sees.
-    async fn tool_get_thread_messages(&self, args: &serde_json::Value) -> String {
+    async fn tool_get_thread_messages(
-        let Some(contact_id) = args.get("contact_id").and_then(|v| v.as_i64()) else {
+        &self,
-            return "Error: missing required parameter 'contact_id'".to_string();
+        args: &serde_json::Value,
+        thread_contact: Option<i64>,
+    ) -> String {
+        let contact_id = match Self::bound_thread(args, thread_contact) {
+            Ok(c) => c,
+            Err(e) => return e,
         };
         let Some(message_id) = args.get("message_id").and_then(|v| v.as_i64()) else {
             return "Error: missing required parameter 'message_id'".to_string();
@@ -2461,10 +2470,12 @@ Return ONLY the summary, nothing else."#,
     async fn tool_look_at_message_image(
         &self,
         args: &serde_json::Value,
+        thread_contact: Option<i64>,
         local: &dyn LlmClient,
     ) -> String {
-        let Some(contact_id) = args.get("contact_id").and_then(|v| v.as_i64()) else {
+        let contact_id = match Self::bound_thread(args, thread_contact) {
-            return "Error: missing required parameter 'contact_id'".to_string();
+            Ok(c) => c,
+            Err(e) => return e,
         };
         let Some(message_id) = args.get("message_id").and_then(|v| v.as_i64()) else {
             return "Error: missing required parameter 'message_id'".to_string();
@@ -2476,11 +2487,15 @@ Return ONLY the summary, nothing else."#,
 
         let bytes = match self
             .sms_client
-            .fetch_mms_media(contact_id, message_id, media_index)
+            .fetch_mms_image(contact_id, message_id, media_index)
             .await
         {
             Ok(b) => b,
-            Err(e) => return format!("Error fetching attachment: {}", e),
+            Err(e) => {
+                return format!(
+                    "Error: couldn't look at that attachment ({e}); only photos can be viewed."
+                );
+            }
         };
         let image_base64 = match Self::encode_image_bytes_for_vision(&bytes) {
             Ok(b64) => b64,
@@ -2501,7 +2516,12 @@ Return ONLY the summary, nothing else."#,
     async fn tool_get_photos_near_time(&self, args: &serde_json::Value) -> String {
         let zone = self.display_zone();
         let server_zone = crate::camera_tz::server_zone();
-        let Some(center) = Self::parse_moment(args, zone) else {
+        let center_arg = args
+            .get("timestamp")
+            .filter(|v| !v.is_null())
+            .or_else(|| args.get("datetime"));
+        let Some(center) = center_arg.and_then(|v| crate::ai::date_info::parse_center(v, zone))
+        else {
             return "Error: pass 'timestamp' (unix seconds) or 'datetime' (YYYY-MM-DD HH:MM)"
                 .to_string();
         };
@@ -2553,11 +2573,22 @@ Return ONLY the summary, nothing else."#,
             let when = crate::date_view::row_display_wall(&row, zone, server_zone)
                 .map(|w| w.format("%Y-%m-%d %H:%M").to_string())
                 .unwrap_or_else(|| "unknown time".to_string());
+            // Tags follow the bytes: union over every path holding the same
+            // content, so a copy in another library shows its tags too.
+            let sibling_paths = {
+                let mut dao = self.exif_dao.lock().expect("Unable to lock ExifDao");
+                dao.get_rel_paths_sharing_content(row.library_id, &row.file_path)
+                    .unwrap_or_else(|_| vec![row.file_path.clone()])
+            };
             let tags: Vec<String> = {
                 let mut dao = self.tag_dao.lock().expect("Unable to lock TagDao");
-                dao.get_tags_for_path(&row.file_path)
+                let mut names: Vec<String> = dao
+                    .get_tags_for_paths(&sibling_paths)
                     .map(|t| t.into_iter().map(|t| t.name).collect())
-                    .unwrap_or_default()
+                    .unwrap_or_default();
+                names.sort();
+                names.dedup();
+                names
             };
             let people: Vec<String> = match &row.content_hash {
                 Some(hash) => {
@@ -2602,6 +2633,14 @@ Return ONLY the summary, nothing else."#,
         if crate::file_types::is_video_file(std::path::Path::new(&file_path)) {
             return "Error: that's a video — only photos can be looked at.".to_string();
         }
+        // Only photos the library has indexed: excluded folders (EXCLUDED_DIRS,
+        // e.g. `private`) are never indexed, so a guessed path into one is
+        // refused rather than read off disk.
+        if self.fetch_exif(&file_path).is_none() {
+            return "Error: that isn't a photo in the library — use a file_path from \
+                    get_photos_near_time."
+                .to_string();
+        }
         let image_base64 = match self.load_image_as_base64(&file_path) {
             Ok(b) => b,
             Err(e) => return format!("Error loading photo: {}", e),
@@ -2612,6 +2651,26 @@ Return ONLY the summary, nothing else."#,
         }
     }
 
+    /// The thread a thread tool may read: the one the chat was started from,
+    /// fixed server-side. A `contact_id` the model passes is only checked
+    /// against it — never trusted — so a chat (practice mode especially) can
+    /// never be talked into reading another conversation.
+    fn bound_thread(args: &serde_json::Value, thread_contact: Option<i64>) -> Result<i64, String> {
+        let Some(bound) = thread_contact else {
+            return Err(
+                "Error: thread tools are only available in a chat started from a \
+                        text thread."
+                    .to_string(),
+            );
+        };
+        match args.get("contact_id").and_then(|v| v.as_i64()) {
+            Some(asked) if asked != bound => {
+                Err("Error: only this chat's own text thread can be read here.".to_string())
+            }
+            _ => Ok(bound),
+        }
+    }
+
     /// A model-supplied path is joined onto each library root, so refuse
     /// anything that could climb out of it.
     fn photo_path_is_safe(path: &str) -> bool {
@@ -2622,28 +2681,6 @@ Return ONLY the summary, nothing else."#,
                 .all(|c| matches!(c, Component::Normal(_) | Component::CurDir))
     }
 
-    /// A tool's centre moment: `timestamp` (unix seconds) wins, else
-    /// `datetime` read as a wall clock in the owner's display zone. A bare
-    /// date centres on midday.
-    fn parse_moment(args: &serde_json::Value, zone: chrono_tz::Tz) -> Option<i64> {
-        if let Some(ts) = args.get("timestamp").and_then(|v| v.as_i64()) {
-            return Some(ts);
-        }
-        let raw = args.get("datetime").and_then(|v| v.as_str())?.trim();
-        let naive = chrono::NaiveDateTime::parse_from_str(raw, "%Y-%m-%d %H:%M")
-            .or_else(|_| chrono::NaiveDateTime::parse_from_str(raw, "%Y-%m-%dT%H:%M"))
-            .or_else(|_| chrono::NaiveDateTime::parse_from_str(raw, "%Y-%m-%dT%H:%M:%S"))
-            .ok()
-            .or_else(|| {
-                NaiveDate::parse_from_str(raw, "%Y-%m-%d")
-                    .ok()
-                    .and_then(|d| d.and_hms_opt(12, 0, 0))
-            })?;
-        zone.from_local_datetime(&naive)
-            .earliest()
-            .map(|dt| dt.timestamp())
-    }
-
     /// Decode arbitrary image bytes (an MMS attachment), shrink to the
     /// vision models' 1024px working size and re-encode as base64 JPEG —
     /// the same shape `load_image_as_base64` produces for library files.
@@ -4062,12 +4099,11 @@ Return ONLY the summary, nothing else."#,
                  thread (the #numbers in the transcript) — `before` for older messages, `after` for what \
                  came next, `around` for both sides. Lines carry their own #id, so call again from the \
                  oldest/newest id to keep paging. \
-                 Example: `{contact_id: 42, message_id: 812, direction: \"before\", limit: 30}`.",
+                 Example: `{message_id: 812, direction: \"before\", limit: 30}`.",
                 serde_json::json!({
                     "type": "object",
-                    "required": ["contact_id", "message_id"],
+                    "required": ["message_id"],
                     "properties": {
-                        "contact_id": { "type": "integer", "description": "The thread's contact_id (given in the system prompt)." },
                         "message_id": { "type": "integer", "description": "Message id to page from." },
                         "direction":  { "type": "string", "enum": ["before", "after", "around"], "description": "Which side of message_id to read (default before)." },
                         "limit":      { "type": "integer", "description": "Max messages (default 30, max 80)." }
@@ -4080,12 +4116,11 @@ Return ONLY the summary, nothing else."#,
                 "Look at a photo that was sent in the SMS thread, using the local vision model. Returns a \
                  visual description. Attachments appear in the transcript as `image #N` on a message line — \
                  pass that message's id and N as media_index. Videos and audio can't be viewed. \
-                 Example: `{contact_id: 42, message_id: 815, media_index: 0}`.",
+                 Example: `{message_id: 815, media_index: 0}`.",
                 serde_json::json!({
                     "type": "object",
-                    "required": ["contact_id", "message_id"],
+                    "required": ["message_id"],
                     "properties": {
-                        "contact_id":  { "type": "integer", "description": "The thread's contact_id." },
                         "message_id":  { "type": "integer", "description": "Id of the message carrying the photo." },
                         "media_index": { "type": "integer", "description": "Which attachment on that message (default 0)." }
                     }
@@ -4843,6 +4878,7 @@ Return ONLY the summary, nothing else."#,
                             &file_path,
                             user_id,
                             &persona_id,
+                            None,
                         )
                         .instrument(loop_span.clone())
                         .await;
@@ -4895,6 +4931,7 @@ Return ONLY the summary, nothing else."#,
                             &file_path,
                             user_id,
                             &persona_id,
+                            None,
                         )
                         .instrument(loop_span.clone())
                         .await;
@@ -5083,6 +5120,7 @@ Return ONLY the summary, nothing else."#,
                             "",
                             0,
                             "",
+                            None,
                         )
                         .await;
                     messages.push(ChatMessage::tool_result(result));
@@ -5124,6 +5162,7 @@ Return ONLY the summary, nothing else."#,
                             "",
                             0,
                             "",
+                            None,
                         )
                         .await;
                     messages.push(ChatMessage::tool_result(result));
@@ -5294,6 +5333,21 @@ mod tests {
         assert!(names.contains(&"look_at_photo"));
     }
 
+    #[test]
+    fn thread_tools_only_read_the_chats_own_thread() {
+        use serde_json::json;
+        // The bound thread is used; the model needn't (and can't) choose.
+        assert_eq!(InsightGenerator::bound_thread(&json!({}), Some(42)), Ok(42));
+        assert_eq!(
+            InsightGenerator::bound_thread(&json!({"contact_id": 42}), Some(42)),
+            Ok(42)
+        );
+        // Another thread is refused, even if the model names it.
+        assert!(InsightGenerator::bound_thread(&json!({"contact_id": 7}), Some(42)).is_err());
+        // No bound thread (not a thread chat): nothing to read.
+        assert!(InsightGenerator::bound_thread(&json!({"contact_id": 42}), None).is_err());
+    }
+
     #[test]
     fn photo_path_is_safe_rejects_escapes() {
         assert!(InsightGenerator::photo_path_is_safe("2019/06/IMG_1.jpg"));
@@ -5303,32 +5357,6 @@ mod tests {
         assert!(!InsightGenerator::photo_path_is_safe(""));
     }
 
-    #[test]
-    fn parse_moment_accepts_unix_and_local_wall_clock() {
-        let tz = chrono_tz::Tz::America__New_York;
-        assert_eq!(
-            InsightGenerator::parse_moment(&serde_json::json!({"timestamp": 1_700_000_000}), tz),
-            Some(1_700_000_000)
-        );
-        // 2023-11-14 17:13 in New York (EST) = 22:13 UTC.
-        assert_eq!(
-            InsightGenerator::parse_moment(
-                &serde_json::json!({"datetime": "2023-11-14 17:13"}),
-                tz
-            ),
-            Some(1_699_999_980)
-        );
-        // A bare date means midday, the least-wrong centre for a whole day.
-        assert_eq!(
-            InsightGenerator::parse_moment(&serde_json::json!({"datetime": "2023-11-14"}), tz),
-            Some(1_699_981_200)
-        );
-        assert_eq!(
-            InsightGenerator::parse_moment(&serde_json::json!({}), tz),
-            None
-        );
-    }
-
     fn place(name: &str, description: &str) -> ApolloPlace {
         ApolloPlace {
             id: 1,

src/ai/persona_chat.rs

@@ -122,6 +122,40 @@ pub fn seed_messages_for_persona(system_prompt: &str) -> Vec<ChatMessage> {
     vec![ChatMessage::system(system_prompt.to_string())]
 }
 
+/// The persona id a practice conversation is stored under. Practice mode
+/// plays the SMS contact, not a persona, so the conversation belongs to no
+/// persona row: deleting or editing personas can't hide or break it.
+pub const PRACTICE_PERSONA_ID: &str = "";
+
+/// Name shown for a practice conversation where a persona name would go.
+pub const PRACTICE_PERSONA_NAME: &str = "Practice";
+
+/// Whether a stored conversation is a practice one (plays the contact).
+fn is_practice(row: &crate::database::persona_dao::PersonaChatRow) -> bool {
+    row.anchor
+        .as_ref()
+        .is_some_and(|a| a.mode == crate::database::AnchorMode::AsContact)
+}
+
+/// The stand-in persona a practice turn runs with. Its prompt is never used
+/// (`anchored_system_prompt` ignores the persona in practice mode) and it
+/// can't correct facts — practice is offered no knowledge tools at all.
+fn practice_persona(user_id: i32) -> crate::database::models::Persona {
+    crate::database::models::Persona {
+        id: 0,
+        user_id,
+        persona_id: PRACTICE_PERSONA_ID.to_string(),
+        name: PRACTICE_PERSONA_NAME.to_string(),
+        system_prompt: String::new(),
+        is_built_in: false,
+        include_all_memories: false,
+        created_at: 0,
+        updated_at: 0,
+        reviewed_only_facts: false,
+        allow_agent_corrections: false,
+    }
+}
+
 /// Parse a persisted transcript into the conversation tree.
 ///
 /// Two on-disk formats are accepted, mirroring the file chat's reader:
@@ -602,8 +636,13 @@ impl PersonaChatSession {
         message_id: i64,
         mode: crate::database::AnchorMode,
     ) -> Result<String, PersonaChatError> {
-        let persona_id = persona_id.trim();
+        // Practice plays the contact; any persona the client sent is ignored.
-        {
+        let persona_id = if mode == crate::database::AnchorMode::AsContact {
+            PRACTICE_PERSONA_ID
+        } else {
+            persona_id.trim()
+        };
+        if mode != crate::database::AnchorMode::AsContact {
             let mut dao = self.persona_dao.lock().expect("persona_dao poisoned");
             let persona = dao
                 .get_persona(user_id, persona_id)
@@ -740,10 +779,13 @@ impl PersonaChatSession {
                 .get_persona_chat(user_id, &conversation_id)
                 .map_err(|e| PersonaChatError::Db(anyhow!("{e:?}")))?
                 .ok_or_else(|| PersonaChatError::UnknownConversation(conversation_id.clone()))?;
-            let persona = dao
+            let persona = if is_practice(&row) {
-                .get_persona(user_id, &row.persona_id)
+                practice_persona(user_id)
+            } else {
+                dao.get_persona(user_id, &row.persona_id)
                     .map_err(|e| PersonaChatError::Db(anyhow!("{e:?}")))?
-                .ok_or_else(|| PersonaChatError::UnknownPersona(row.persona_id.clone()))?;
+                    .ok_or_else(|| PersonaChatError::UnknownPersona(row.persona_id.clone()))?
+            };
             (persona, row.persona_id)
         };
 
@@ -1004,6 +1046,8 @@ impl PersonaChatSession {
             "",
             user_id,
             &persona.persona_id,
+            // Thread tools only ever read this chat's own thread.
+            row.anchor.as_ref().map(|a| a.contact_id),
             max_iterations,
             &entry,
             &mut fitter,
@@ -1119,8 +1163,10 @@ impl PersonaChatSession {
     ) -> Result<Vec<PersonaConversationSummary>> {
         let (rows, personas) = {
             let mut dao = self.persona_dao.lock().expect("persona_dao poisoned");
-            let rows = dao
+            let rows = match contact_id {
-                .list_persona_chats(user_id)
+                Some(cid) => dao.list_persona_chats_for_contact(user_id, cid),
+                None => dao.list_persona_chats(user_id),
+            }
             .map_err(|e| anyhow!("failed to list persona chats: {e:?}"))?;
             let personas = dao
                 .list_personas(user_id)
@@ -1134,13 +1180,13 @@ impl PersonaChatSession {
 
         let mut out = Vec::with_capacity(rows.len());
         for entry in rows {
-            if let Some(cid) = contact_id
+            let persona_name = if is_practice(&entry) {
-                && entry.anchor.as_ref().map(|a| a.contact_id) != Some(cid)
+                PRACTICE_PERSONA_NAME.to_string()
-            {
+            } else {
-                continue;
+                match names.get(&entry.persona_id) {
+                    Some(name) => name.clone(),
+                    None => continue,
                 }
-            let Some(persona_name) = names.get(&entry.persona_id).cloned() else {
-                continue;
             };
             // A single unreadable transcript shouldn't take the whole list
             // down with it — skip the row and keep going.
@@ -1372,6 +1418,9 @@ pub struct PersonaChatHistoryQuery {
 /// Body for POST /persona_chat/conversations — start a new conversation.
 #[derive(Debug, Deserialize)]
 pub struct PersonaChatCreateRequest {
+    /// Required except for a practice (`as_contact`) anchor, which plays
+    /// the contact rather than a persona.
+    #[serde(default)]
     pub persona_id: String,
     /// Anchor the conversation on a message in an SMS thread ("Continue
     /// with persona"). Omitted for an open chat.
@@ -2038,6 +2087,24 @@ mod tests {
         assert!(tracker.claim("conv-a", "t7").is_ok());
     }
 
+    #[test]
+    fn practice_create_request_needs_no_persona() {
+        let req: PersonaChatCreateRequest = serde_json::from_str(
+            r#"{"anchor":{"contact_id":42,"message_id":812,"mode":"as_contact"}}"#,
+        )
+        .unwrap();
+        assert_eq!(req.persona_id, "");
+    }
+
+    #[test]
+    fn practice_persona_is_inert() {
+        let p = practice_persona(7);
+        assert_eq!(p.persona_id, PRACTICE_PERSONA_ID);
+        assert_eq!(p.user_id, 7);
+        assert!(p.system_prompt.is_empty());
+        assert!(!p.allow_agent_corrections);
+    }
+
     #[test]
     fn create_request_anchor_mode_defaults_to_about() {
         use crate::database::AnchorMode;

src/ai/sms_anchor.rs

@@ -139,7 +139,6 @@ struct PromptParts {
     contact: String,
     when: String,
     thread: String,
-    cid: i64,
     mid: i64,
 }
 
@@ -165,7 +164,6 @@ fn prompt_parts(anchor: &SmsAnchor, tz: Tz) -> PromptParts {
         contact,
         when,
         thread,
-        cid: anchor.contact_id,
         mid: anchor.message_id,
     }
 }
@@ -196,7 +194,6 @@ fn about_prompt(persona_prompt: &str, parts: &PromptParts, user_name: &str) -> S
         contact,
         when,
         thread,
-        cid,
         mid,
     } = parts;
     format!(
@@ -227,11 +224,11 @@ the lookups. Look at one or two photos that matter, not every one you find.
 - You can read and look, but you can't send photos or texts to anyone — \
 don't offer to.
 
-Tools for this thread (contact_id {cid}; #numbers below are message ids):
+Tools for this thread (#numbers below are message ids):
-- get_thread_messages {{contact_id: {cid}, message_id: {mid}, direction: \"before\"}} \
+- get_thread_messages {{message_id: {mid}, direction: \"before\"}} — earlier \
-— earlier messages; \"after\" for what came next.
+messages; \"after\" for what came next.
-- look_at_message_image {{contact_id: {cid}, message_id, media_index}} — see a \
+- look_at_message_image {{message_id, media_index}} — see a photo sent in the \
-photo sent in the thread (attachments are listed as `image #N`).
+thread (attachments are listed as `image #N`).
 - get_photos_near_time {{timestamp}} — photos from {user_name}'s library taken \
 around a moment, with their tags and the people in them.
 - look_at_photo {{file_path}} — see one of those library photos.
@@ -247,23 +244,40 @@ fn practice_prompt(parts: &PromptParts, user_name: &str) -> String {
         contact,
         when,
         thread,
-        cid,
         mid,
     } = parts;
     format!(
-        "You are playing {contact} in a text conversation with {user_name}, so {user_name} can practise picking the conversation back up. This is a private rehearsal for {user_name}; the real {contact} is not part of it.
+        "You are playing {contact} in a text conversation with {user_name}, so \
+{user_name} can practise picking the conversation back up. This is a private \
+rehearsal for {user_name}; the real {contact} is not part of it.
 
-Below is the real thread up to the message marked ▶ (sent {when}). Carry on from there as {contact}: {user_name}'s messages to you are their next texts, and every reply you write is {contact}'s next text.
+Below is the real thread up to the message marked ▶ (sent {when}). Carry on \
+from there as {contact}: {user_name}'s messages to you are their next texts, \
+and every reply you write is {contact}'s next text.
 
 How to play it:
-- Sound like {contact} does in the thread — their message length, slang, emoji, punctuation, humour, how fast they get to the point. Mirror them, not a generic texter.
+- Sound like {contact} does in the thread — their message length, slang, \
-- Write only the text itself. No narration, no stage directions, no 'As {contact}, I\'d say…'. Separate several short texts with a blank line.
+emoji, punctuation, humour, how fast they get to the point. Mirror them, not \
-- Stay true to what {contact} knows and feels in the thread. Don't invent big facts about their life — jobs, relationships, events — that the thread doesn't support; if asked about something they couldn't know, answer vaguely or deflect the way they plausibly would.
+a generic texter.
-- React like a real person: it's fine to be busy, short, unconvinced, or to ask something back. Don't be more agreeable than {contact} actually is in the thread.
+- Write only the text itself. No narration, no stage directions, no 'As \
+{contact}, I\'d say…'. Separate several short texts with a blank line.
+- Stay true to what {contact} knows and feels in the thread. Don't invent \
+big facts about their life — jobs, relationships, events — that the thread \
+doesn't support; if asked about something they couldn't know, answer vaguely \
+or deflect the way they plausibly would.
+- React like a real person: it's fine to be busy, short, unconvinced, or to \
+ask something back. Don't be more agreeable than {contact} actually is in \
+the thread.
 - It is shortly after the ▶ message unless {user_name} says time has passed.
-- If {user_name} steps out of the rehearsal ('pause', 'out of character', 'how did that sound?'), drop the role and answer briefly as a coach: honest, specific feedback on how their texts are landing. Go back to being {contact} when they carry on.
+- If {user_name} steps out of the rehearsal ('pause', 'out of character', \
+'how did that sound?'), drop the role and answer briefly as a coach: honest, \
+specific feedback on how their texts are landing. Go back to being {contact} \
+when they carry on.
 
-If you need to remember an earlier part of the thread, use get_thread_messages {{contact_id: {cid}, message_id: {mid}, direction: \"before\"}}; to see a photo sent in it (`image #N` on a line), use look_at_message_image {{contact_id: {cid}, message_id, media_index}}. Never mention either.
+If you need to remember an earlier part of the thread, use \
+get_thread_messages {{message_id: {mid}, direction: \"before\"}}; to see a \
+photo sent in it (`image #N` on a line), use look_at_message_image \
+{{message_id, media_index}}. Never mention either.
 
 Thread between {user_name} and {contact}:
 {thread}"
@@ -368,8 +382,10 @@ mod tests {
         };
         let prompt = anchored_system_prompt("You are Journal.", &anchor, "Cam", Tz::UTC);
         assert!(prompt.starts_with("You are Journal."));
-        assert!(prompt.contains("contact_id 42"));
         assert!(prompt.contains("message_id: 812"));
+        // The thread is bound server-side; the prompt doesn't hand the
+        // model a contact id to choose.
+        assert!(!prompt.contains("contact_id"));
         assert!(prompt.contains("You are not Sam"));
         assert!(prompt.ends_with("Sam: see you there"));
     }
@@ -405,7 +421,8 @@ mod tests {
             !prompt.contains("You are Journal."),
             "a persona voice would bleed into the contact's"
         );
-        assert!(prompt.contains("contact_id: 42"));
+        assert!(prompt.contains("message_id: 812"));
+        assert!(!prompt.contains("contact_id"));
         assert!(prompt.contains("out of character"));
         assert!(prompt.ends_with("Sam: see you there"));
     }

src/ai/sms_client.rs

@@ -425,10 +425,14 @@ impl SmsApiClient {
         })
     }
 
-    /// Download one MMS attachment. `media_index` is the attachment's
+    /// Download one MMS *image*. `media_index` is the attachment's position
-    /// position among the message's image/video/audio parts — the same
+    /// among the message's image/video/audio parts — the same index
-    /// index SMS-API's `/media/{message}/{index}/file/` route takes.
+    /// SMS-API's `/media/{message}/{index}/file/` route takes.
-    pub async fn fetch_mms_media(
+    ///
+    /// Checks the response before reading the body, so pointing this at a
+    /// video or audio attachment costs a header round-trip, not the whole
+    /// file in memory; images over [`MMS_IMAGE_MAX_BYTES`] are refused too.
+    pub async fn fetch_mms_image(
         &self,
         contact_id: i64,
         message_id: i64,
@@ -442,14 +446,29 @@ impl SmsApiClient {
         if let Some(token) = &self.token {
             request = request.header("Authorization", format!("Bearer {}", token));
         }
-        let response = request.send().await?;
+        let mut response = request.send().await?;
         if !response.status().is_success() {
             return Err(anyhow::anyhow!(
                 "MMS media request failed: {}",
                 response.status()
             ));
         }
-        Ok(response.bytes().await?.to_vec())
+        let content_type = response
+            .headers()
+            .get(reqwest::header::CONTENT_TYPE)
+            .and_then(|v| v.to_str().ok())
+            .map(str::to_string);
+        check_mms_image_response(content_type.as_deref(), response.content_length())
+            .map_err(|e| anyhow::anyhow!(e))?;
+        // Content-Length can be absent (chunked); cap while reading too.
+        let mut bytes = Vec::new();
+        while let Some(chunk) = response.chunk().await? {
+            if bytes.len() + chunk.len() > MMS_IMAGE_MAX_BYTES {
+                return Err(anyhow::anyhow!("attachment is larger than the image limit"));
+            }
+            bytes.extend_from_slice(&chunk);
+        }
+        Ok(bytes)
     }
 
     pub async fn summarize_context(
@@ -504,6 +523,29 @@ pub struct SmsMessage {
     pub is_sent: bool,
 }
 
+/// Largest MMS image `fetch_mms_image` will download. Phone photos sent by
+/// MMS are a few MB; anything past this is not worth decoding for a
+/// 1024px vision description.
+pub const MMS_IMAGE_MAX_BYTES: usize = 20 * 1024 * 1024;
+
+/// Decide from the response headers whether an MMS attachment is an image
+/// worth downloading. A missing content type is allowed through (the
+/// decoder decides); a declared non-image or an oversized length is not.
+fn check_mms_image_response(
+    content_type: Option<&str>,
+    content_length: Option<u64>,
+) -> Result<(), String> {
+    if let Some(ct) = content_type
+        && !ct.trim().to_ascii_lowercase().starts_with("image/")
+    {
+        return Err(format!("attachment is {ct}, not an image"));
+    }
+    if content_length.is_some_and(|n| n > MMS_IMAGE_MAX_BYTES as u64) {
+        return Err("attachment is larger than the image limit".to_string());
+    }
+    Ok(())
+}
+
 /// A thread participant as SMS-API's conversation endpoint describes it.
 #[derive(Debug, Clone, Deserialize)]
 pub struct ThreadContact {
@@ -747,6 +789,23 @@ mod tests {
         );
     }
 
+    #[test]
+    fn mms_image_check_refuses_non_images_and_huge_files_before_download() {
+        assert!(check_mms_image_response(Some("image/jpeg"), Some(2_000_000)).is_ok());
+        assert!(check_mms_image_response(Some("IMAGE/PNG"), None).is_ok());
+        assert!(check_mms_image_response(None, None).is_ok());
+        assert!(
+            check_mms_image_response(Some("video/mp4"), Some(1))
+                .unwrap_err()
+                .contains("video/mp4")
+        );
+        assert!(check_mms_image_response(Some("audio/amr"), None).is_err());
+        assert!(
+            check_mms_image_response(Some("image/jpeg"), Some(MMS_IMAGE_MAX_BYTES as u64 + 1))
+                .is_err()
+        );
+    }
+
     #[test]
     fn thread_contact_falls_back_to_the_address() {
         let c = ThreadContact {

src/database/persona_dao.rs

@@ -232,6 +232,15 @@ pub trait PersonaDao: Sync + Send {
     /// derived from the tree rather than denormalized into its own column.
     fn list_persona_chats(&mut self, user_id: i32) -> Result<Vec<PersonaChatRow>, DbError>;
 
+    /// Conversations anchored on one SMS thread, newest first. Backs the
+    /// Messages screen's per-thread list; served by
+    /// `idx_persona_chat_anchor_contact`.
+    fn list_persona_chats_for_contact(
+        &mut self,
+        user_id: i32,
+        contact_id: i64,
+    ) -> Result<Vec<PersonaChatRow>, DbError>;
+
     /// Start a new conversation with a persona, returning its id. Several
     /// conversations with the same persona are expected, so this never
     /// reuses an existing row.
@@ -524,6 +533,26 @@ impl PersonaDao for SqlitePersonaDao {
         .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
     }
 
+    fn list_persona_chats_for_contact(
+        &mut self,
+        uid: i32,
+        cid: i64,
+    ) -> Result<Vec<PersonaChatRow>, DbError> {
+        trace_db_call("query", "list_persona_chats_for_contact", |_span| {
+            use schema::persona_chat_conversations::dsl::*;
+            let mut conn = self.connection.lock().expect("PersonaDao lock");
+            persona_chat_conversations
+                .filter(user_id.eq(uid))
+                .filter(anchor_contact_id.eq(cid))
+                .order(updated_at.desc())
+                .select(persona_chat_select!())
+                .load::<PersonaChatColumns>(conn.deref_mut())
+                .map(|rows| rows.into_iter().map(persona_chat_row).collect())
+                .map_err(|e| anyhow::anyhow!("Query error: {}", e))
+        })
+        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
+    }
+
     fn create_persona_chat(
         &mut self,
         uid: i32,
@@ -932,6 +961,37 @@ mod tests {
         );
     }
 
+    #[test]
+    fn persona_chat_list_for_contact_returns_only_that_thread() {
+        let (mut dao, uid) = dao_with_user("p11");
+        let anchor = |contact_id| SmsAnchor {
+            contact_id,
+            contact_name: "x".to_string(),
+            message_id: 1,
+            timestamp: 0,
+            context: String::new(),
+            mode: AnchorMode::About,
+        };
+        let older = dao
+            .create_anchored_persona_chat(uid, "journal", 100, &anchor(42))
+            .unwrap();
+        let _other = dao
+            .create_anchored_persona_chat(uid, "journal", 150, &anchor(7))
+            .unwrap();
+        let _open = dao.create_persona_chat(uid, "journal", 175).unwrap();
+        let newer = dao
+            .create_anchored_persona_chat(uid, "journal", 200, &anchor(42))
+            .unwrap();
+
+        let ids: Vec<String> = dao
+            .list_persona_chats_for_contact(uid, 42)
+            .unwrap()
+            .into_iter()
+            .map(|r| r.conversation_id)
+            .collect();
+        assert_eq!(ids, vec![newer, older]);
+    }
+
     #[test]
     fn anchor_mode_reads_null_and_unknown_as_about() {
         assert_eq!(AnchorMode::from_column(None), AnchorMode::About);