feat(agents): let a bundled agent get its community's media as its owner

docs/agents.md

@@ -79,10 +79,11 @@ servers do not support these operations.
 
 In communities the build flag `BUZZ_OWNER_MCP_COMMUNITIES` enables, an agent's
 runs in this app on a bundled harness list `owner_channel_list`, `owner_channel_get`,
-`owner_member_list`, `owner_read`, `owner_canvas_get` and `owner_canvas_history`.
+`owner_member_list`, `owner_read`, `owner_canvas_get`, `owner_canvas_history`
+and `owner_media_get`.
 They read the owner's channels, one channel's details and
 the owner's rights in it, its roster, its messages, whole threads and searches,
-and its Canvas and earlier revisions, through the
+its Canvas and earlier revisions, and the community's media, through the
 owner's own signed-in session, including private and archived channels, DMs and
 Solo chats the agent is not in. Message reads and Canvas history page with a
 `next` cursor, as `read` and the app's history do. A search covers only the
@@ -91,10 +92,16 @@ channels' matches still fill its page, so `limited` with few results means
 narrowing it by channel or time. A message shows its newest edit by its author
 or, as in the app, by the author's verified owner. One read fetches a page's edits;
 when they fill it, the answer says `edits_limited` and some messages may show earlier text. They write
-nothing: no membership, subscription, read state, post, agent start or Canvas
+nothing to the community: no membership, subscription, read state, post, agent start or Canvas
 change. Content comes from the relay's own answer, not the owner's open views,
-so it changes no unread counts. They do not save the owner's attachments: a
-saved file would be readable before the call's final checks. The app
+so it changes no unread counts. `owner_media_get` gets one media blob of the
+agent's community, by its URL or `sha256[.ext]`, as `media_get` does but signed
+as the owner: the app holds it in memory, up to 500 MiB, until protection has
+reviewed the answer, and saves it to a local file only after the call's final
+checks, while the owner is still signed in and the agent was not deleted. A
+refused, cancelled or failed call saves nothing. Agents running on a remote
+execution target do not list it and are refused it, since its file would be
+on this device. The app
 decides the agent, owner and community;
 answers name them in `executedAs`. Each call needs the agent's owner signed in
 to that community now and fails, returning nothing, when the account, community

docs/buzz-help.md

@@ -836,10 +836,11 @@ available rather than silently discarding it.
 
 - In communities where your build enables it, an agent running on this
   device with a built-in harness can list your channels, including private and
-  archived ones, DMs and Solo chats it is not in, and see a channel's details
-  and members, read with your access. It cannot change anything this way, and
-  it stops working when you sign out, switch accounts, disconnect or stop its
-  turn.
+  archived ones, DMs and Solo chats it is not in, and read a channel's details,
+  members, messages and Canvas, and the community's files, with your access.
+  It cannot change anything this way, and it stops working when you sign out,
+  switch accounts, disconnect or stop its turn. An agent on a remote execution
+  target cannot get files this way.
 
 Saved teams from **Your teams** appear in the inline `@` suggestions and the
 mention picker. Select a team to insert its members as individual mentions.

src-tauri/build.rs

@@ -208,6 +208,9 @@ fn main() {
             "app_agent_search_profiles",
             "app_agent_upload",
             "app_agent_media",
+            "app_agent_owner_media_stage",
+            "app_agent_owner_media_publish",
+            "app_agent_owner_media_discard",
             "app_agent_git_auth",
             "app_agent_remember",
             "app_agent_claim",

src-tauri/capabilities/default.json

@@ -154,6 +154,9 @@
     "allow-app-agent-search-profiles",
     "allow-app-agent-upload",
     "allow-app-agent-media",
+    "allow-app-agent-owner-media-stage",
+    "allow-app-agent-owner-media-publish",
+    "allow-app-agent-owner-media-discard",
     "allow-app-agent-git-auth",
     "allow-app-agent-remember",
     "allow-app-agent-claim",

src-tauri/src/app_agents.rs

@@ -20,6 +20,8 @@ use crate::federated_identity::{
     assertion,
 };
 
+pub(crate) mod owner_media;
+
 /// A NIP-98 `Authorization` header for one signed HTTP auth event.
 fn authorization(event: Value) -> Result<String, String> {
     use base64::Engine;
@@ -56,6 +58,8 @@ pub(crate) struct AppAgentHost {
     tokens: AgentTokens,
     /// Serializes owner prompts, without holding cross-process identity/custody locks.
     protection_upgrade: Arc<Mutex<()>>,
+    /// Owner media read for review and not yet published.
+    owner_media: Arc<owner_media::OwnerMedia>,
 }
 impl AppAgentHost {
     /// `packaged` is false for a dev build, which steps aside for a packaged app.
@@ -103,6 +107,7 @@ impl AppAgentHost {
             }),
             tokens,
             protection_upgrade: Arc::default(),
+            owner_media: Arc::default(),
         }
     }
     /// The saved identities, for readers outside Agents such as the inventory.
@@ -119,6 +124,12 @@ impl AppAgentHost {
         let mut removals = self.removals();
         removals.page += 1;
         removals.held.clear();
+        drop(removals);
+        self.owner_media.clear();
+    }
+    /// Drops held owner media, as the window closing publishes none.
+    pub(crate) fn owner_media_clear(&self) {
+        self.owner_media.clear();
     }
     fn keys(&self) -> std::sync::MutexGuard<'_, HashMap<String, Arc<Secret>>> {
         self.keys
@@ -1412,19 +1423,7 @@ async fn save_media_admitted(
         }
     }
     agent.verify_media_hash(url, &format!("{:x}", hash.finalize()))?;
-    // The blob's own name, so the same media is saved once; with an extension
-    // from its type when the URL gives none.
-    let mut name = url.rsplit('/').next().unwrap_or_default().to_owned();
-    if !name.contains('.') {
-        if let Some(ext) = mime
-            .split_once('/')
-            .map(|(_, subtype)| subtype)
-            .filter(|ext| ext.len() <= 8 && ext.bytes().all(|b| b.is_ascii_alphanumeric()))
-        {
-            name = format!("{name}.{ext}");
-        }
-    }
-    let path = dir.join(name);
+    let path = dir.join(media_name(url, &mime));
     let persist = || {
         file.persist(&path)
             .map(drop)
@@ -1444,6 +1443,22 @@ async fn save_media_admitted(
     })
 }
 
+/// The blob's own name, so the same media is saved once; with an extension
+/// from its type when the URL gives none.
+fn media_name(url: &str, mime: &str) -> String {
+    let mut name = url.rsplit('/').next().unwrap_or_default().to_owned();
+    if !name.contains('.') {
+        if let Some(ext) = mime
+            .split_once('/')
+            .map(|(_, subtype)| subtype)
+            .filter(|ext| ext.len() <= 8 && ext.bytes().all(|b| b.is_ascii_alphanumeric()))
+        {
+            name = format!("{name}.{ext}");
+        }
+    }
+    name
+}
+
 /// Writes one memory entry, encrypted to the agent's owner; a null body
 /// deletes it. `after` is the `created_at` of the entry it replaces, or 0.
 #[tauri::command]
@@ -1743,6 +1758,7 @@ mod tests {
             hosting: Arc::new(hosting(Err("unused".into()), true)),
             tokens: AgentTokens::unconfigured(),
             protection_upgrade: Arc::default(),
+            owner_media: Arc::default(),
         };
         let agent = AppAgent {
             pubkey: key.pubkey().into(),
@@ -1932,6 +1948,7 @@ mod tests {
             hosting: Arc::new(hosting(Err("unused".into()), true)),
             tokens: f.tokens.clone(),
             protection_upgrade: Arc::default(),
+            owner_media: Arc::default(),
         };
         let import = |key: &Secret| {
             let key = Secret::parse(&key.hex(), key.pubkey()).unwrap();
@@ -2028,6 +2045,7 @@ mod tests {
             hosting: Arc::new(hosting(Err("unused".into()), true)),
             tokens: f.tokens.clone(),
             protection_upgrade: Arc::default(),
+            owner_media: Arc::default(),
         };
         let agents = host.agents().unwrap();
 
@@ -2073,6 +2091,7 @@ mod tests {
             hosting: Arc::new(hosting(Err("unused".into()), true)),
             tokens: f.tokens.clone(),
             protection_upgrade: Arc::default(),
+            owner_media: Arc::default(),
         };
         let import = || {
             let key = Secret::parse(&key.hex(), key.pubkey()).unwrap();
@@ -2523,6 +2542,7 @@ mod tests {
             hosting: Arc::new(hosting(Err("unused".into()), true)),
             tokens: AgentTokens::unconfigured(),
             protection_upgrade: Arc::default(),
+            owner_media: Arc::default(),
         };
         let import = || {
             let prepared = AppAgents::adopt(