feat(#1065): web_tools tool group gates WebFetch/WebSearch built-ins

Replaces the earlier capability-based approach (closed #1069) with a
ToolGroup — capabilities are for privileged system access, web egress is
a tool permission.

Add ToolGroup::WebTools to hive-sh4re:
- tools() returns &[] (no MCP tools gated)
- builtin_tools() returns &["WebFetch", "WebSearch"] — new method on ToolGroup
- Present in ALL and as_str() → "web_tools"

In hive-ag3nt/mcp.rs:
- allowed_tools_arg() now iterates group.builtin_tools() to prepend any
  group-gated built-ins alongside the base ALLOWED_BUILTIN_TOOLS set
- builtin_tools_arg_for_flavor(flavor) replaces builtin_tools_arg() so
  the flavor-correct effective groups are used when building --tools
- builtin_tools_arg() kept as a flavor=Agent convenience alias
- turn.rs updated to call builtin_tools_arg_for_flavor(files.flavor) so
  manager sessions also see web tools when web_tools is in their groups

The dashboard T00L GR0UPS table gains a web_tools column automatically
(ToolGroup::ALL drives the columns).

hive-ag3nt/src/mcp.rs

@@ -1895,9 +1895,10 @@ impl ServerHandler for ManagerServer {}
 /// tools as `mcp__<this>__<tool>` (e.g. `mcp__hyperhive__send`).
 pub const SERVER_NAME: &str = "hyperhive";
 
-/// Built-in claude tools the turn loop enables via `--tools`. Anything not
-/// in this list literally doesn't exist in the session (claude won't even
-/// try to call it). Web egress (`WebFetch`/`WebSearch`) and nested agents
+/// Built-in claude tools always present in every session. Anything not
+/// in this list (or added by `extra_builtin_tools`) literally doesn't
+/// exist in the session. Web egress (`WebFetch`/`WebSearch`) are
+/// tool-group-gated (`web_tools`) — off by default. Nested agents
 /// (`Task`) are intentionally omitted. `Bash` is disallowed — shell
 /// execution goes through `mcp__hyperhive__bash_run` (background tasks
 /// with structured output) instead of a raw interactive shell. `TodoWrite`
@@ -2035,13 +2036,19 @@ pub fn allowed_mcp_tools(groups: &[hive_sh4re::ToolGroup]) -> Vec<String> {
 /// both the built-ins and the MCP surface.
 #[must_use]
 pub fn allowed_tools_arg(flavor: Flavor) -> String {
-    let mut all: Vec<String> = ALLOWED_BUILTIN_TOOLS
-        .iter()
-        .map(|s| (*s).to_owned())
-        .collect();
     let groups = effective_tool_groups(flavor);
+    // Base built-ins always present.
+    let mut all: Vec<String> = ALLOWED_BUILTIN_TOOLS.iter().map(|s| (*s).to_owned()).collect();
+    // Extra built-ins gated by tool groups (e.g. WebFetch/WebSearch via web_tools).
+    for group in &groups {
+        for tool in group.builtin_tools() {
+            if !all.iter().any(|t| t == *tool) {
+                all.push((*tool).to_owned());
+            }
+        }
+    }
     all.extend(allowed_mcp_tools(&groups));
-    // Capability-gated tools: added to --allowedTools when HIVE_CAPABILITIES
+    // Capability-gated MCP tools: added to --allowedTools when HIVE_CAPABILITIES
     // includes the corresponding capability. hive-c0re performs a second
     // server-side check, so this is a usability gate (no annoying prompts),
     // not the security boundary.
@@ -2052,10 +2059,28 @@ pub fn allowed_tools_arg(flavor: Flavor) -> String {
 }
 
 /// Built-in tools list for `--tools` (which built-ins exist in this
-/// session). Same as `ALLOWED_BUILTIN_TOOLS` but joined comma-separated.
+/// session). Base set plus any group-gated built-ins (e.g.
+/// `WebFetch`/`WebSearch` when the `web_tools` group is active).
 #[must_use]
 pub fn builtin_tools_arg() -> String {
-    ALLOWED_BUILTIN_TOOLS.join(",")
+    builtin_tools_arg_for_flavor(Flavor::Agent)
+}
+
+/// Flavor-aware variant used by `turn.rs` via `builtin_tools_arg`. Reads
+/// the effective tool groups for `flavor` so `--tools` matches what
+/// `--allowedTools` includes for the same session.
+#[must_use]
+pub fn builtin_tools_arg_for_flavor(flavor: Flavor) -> String {
+    let groups = effective_tool_groups(flavor);
+    let mut tools: Vec<&str> = ALLOWED_BUILTIN_TOOLS.to_vec();
+    for group in &groups {
+        for t in group.builtin_tools() {
+            if !tools.contains(t) {
+                tools.push(t);
+            }
+        }
+    }
+    tools.join(",")
 }
 
 /// Where the NixOS module writes the per-agent extra-MCP spec (see

hive-ag3nt/src/turn.rs

@@ -672,7 +672,7 @@ async fn run_claude(prompt: &str, files: &TurnFiles, bus: &Bus) -> Result<(bool,
         .arg(&files.mcp_config)
         .arg("--strict-mcp-config")
         .arg("--tools")
-        .arg(mcp::builtin_tools_arg())
+        .arg(mcp::builtin_tools_arg_for_flavor(files.flavor))
         .arg("--allowedTools")
         .arg(mcp::allowed_tools_arg(files.flavor));
     let mut child = cmd

hive-sh4re/src/lib.rs

@@ -774,10 +774,18 @@ pub enum ToolGroup {
     Diagnostics,
     /// `bash_run`, `bash_status`
     Execution,
+    /// Claude built-in web egress tools: `WebFetch` (retrieve a URL) and
+    /// `WebSearch` (search the web). Both are omitted from `--tools` by
+    /// default; adding this group to an agent enables them in the session
+    /// and in `--allowedTools` so they run without a confirmation prompt.
+    /// Does not gate any MCP tools — `tools()` returns `&[]`.
+    WebTools,
 }
 
 impl ToolGroup {
     /// The MCP tool names (without the `mcp__hyperhive__` prefix) in this group.
+    /// Returns `&[]` for `WebTools` — it enables Claude built-in tools,
+    /// not MCP tools; see `builtin_tools()`.
     #[must_use]
     pub fn tools(self) -> &'static [&'static str] {
         match self {
@@ -804,6 +812,18 @@ impl ToolGroup {
             ],
             Self::Diagnostics => &["get_logs"],
             Self::Execution => &["bash_run", "bash_status"],
+            Self::WebTools => &[],
+        }
+    }
+
+    /// The Claude built-in tool names enabled by this group. Only
+    /// `WebTools` returns a non-empty slice; all other groups return `&[]`
+    /// (they control MCP tools via `tools()` instead).
+    #[must_use]
+    pub fn builtin_tools(self) -> &'static [&'static str] {
+        match self {
+            Self::WebTools => &["WebFetch", "WebSearch"],
+            _ => &[],
         }
     }
 
@@ -837,6 +857,7 @@ impl ToolGroup {
         Self::Scheduling,
         Self::Diagnostics,
         Self::Execution,
+        Self::WebTools,
     ];
 
     /// The `snake_case` wire name for this group (matches `serde(rename_all =
@@ -852,6 +873,7 @@ impl ToolGroup {
             Self::Scheduling => "scheduling",
             Self::Diagnostics => "diagnostics",
             Self::Execution => "execution",
+            Self::WebTools => "web_tools",
         }
     }
 }