brokerd: ask_memory, a built-in memory tool that memoryd runs

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/brokerd/src/builtin.rs

@@ -1,6 +1,7 @@
-//! The built-in grants of `recall` and `memory` (M5a spec, section 8). Reading and writing memory
-//! is what an agent is, so no grant file can turn it off or put questions in front of it; the
-//! prompt is protected by `memoryd`, which lets only clean sessions edit identity.
+//! The built-in grants of `recall`, `memory` and `ask_memory` (M5a spec, section 8; M5c spec,
+//! section 9). Reading and writing memory is what an agent is, so no grant file can turn it off or
+//! put questions in front of it; the prompt is protected by `memoryd`, which lets only clean
+//! sessions edit identity.
 
 use bxcore::{Grant, GrantProblem, sha256};
 
@@ -12,17 +13,23 @@ pub const RESERVED: &str = "builtin-";
 /// The built-in grants' text, hashed for the audit log like a grant file's bytes.
 pub const RECALL: &str = "tool = \"recall\"\nmode = \"auto\"\nmax_taint = \"secret\"\nresult_class = \"private\"\nuntrusted = false\n";
 pub const MEMORY: &str = "tool = \"memory\"\nmode = \"auto\"\nmax_taint = \"secret\"\nresult_class = \"private\"\nuntrusted = false\n";
+pub const ASK_MEMORY: &str = "tool = \"ask_memory\"\nmode = \"auto\"\nmax_taint = \"secret\"\nresult_class = \"private\"\nuntrusted = false\n";
 
 /// The sentence for an owner's grant naming a memory tool.
-pub const BUILT_IN: &str = "the policy of recall and memory is built in; remove this grant";
+pub const BUILT_IN: &str =
+    "the policy of recall, memory and ask_memory is built in; remove this grant";
 
-/// The two built-in grants, `builtin-memory` and `builtin-recall`.
+/// The three built-in grants, `builtin-memory`, `builtin-recall` and `builtin-ask-memory`.
 pub fn grants() -> Result<Vec<LoadedGrant>, GrantProblem> {
-    // For each (id, text) of [("builtin-memory", MEMORY), ("builtin-recall", RECALL)]:
+    // For each (id, text) of `sources`:
     // `toml::from_str::<Grant>(text)` and `sha256(text.as_bytes())`, each error as a GrantProblem {
     // file: id, line: None, problem: e.to_string() }; build LoadedGrant { id, grant, sha256 }.
     // Collect into Result<Vec<LoadedGrant>, GrantProblem> (the first error wins).
-    let sources: &[(&str, &str)] = &[("builtin-memory", MEMORY), ("builtin-recall", RECALL)];
+    let sources: &[(&str, &str)] = &[
+        ("builtin-memory", MEMORY),
+        ("builtin-recall", RECALL),
+        ("builtin-ask-memory", ASK_MEMORY),
+    ];
     let mut out: Vec<LoadedGrant> = Vec::new();
     for (id, text) in sources {
         let problem = |error: String| GrantProblem {