hyperhive/hive-sh4re/src/permissions.rs

//! Per-agent authorization: named MCP-tool groups (`ToolGroup`) and
//! system-level capability grants (`Capability`). Both are declared in
//! per-agent config (`tool-groups.json` / `capabilities.json`), injected
//! into the container as env vars, and read by the harness to decide
//! which MCP tools claude actually sees.
//!
//! It also resolves the *built-in* claude tool list ([`builtin_tools_arg`]):
//! that set is group-gated too (`web_tools`), so it belongs next to the
//! groups rather than in any one consumer. Both processes that spawn a
//! `claude` — the harness itself and the subagent daemon — call the same
//! function, so a subagent can never be handed a built-in its parent does
//! not have — with one deliberate exception: [`subagent_builtin_tools_arg`]
//! additionally grants a **subagent** Claude's own `Bash` when the parent
//! holds [`ToolGroup::Execution`]. The parent never gets built-in `Bash`
//! itself (it has the out-of-process `bash` MCP server instead); the
//! capability transfers to a subagent, not the mechanism.

use std::str::FromStr;

use serde::{Deserialize, Serialize};

/// Env var the meta renderer writes with a comma-separated list of
/// [`ToolGroup`] `snake_case` names (e.g. `"messaging,inbox,meta"`). Absent
/// or unparseable means [`ToolGroup::AGENT_DEFAULT`]. See
/// `docs/process/conventions.md::Tool groups`.
pub const TOOL_GROUPS_ENV: &str = "HIVE_TOOL_GROUPS";

/// Built-in claude tools present in every session regardless of tool
/// groups. Anything not in this list (and not added by a group's
/// [`ToolGroup::builtin_tools`]) literally doesn't exist in the session —
/// this is the `--tools` list, which holds even under
/// `--dangerously-skip-permissions`.
///
/// Web egress (`WebFetch`/`WebSearch`) is group-gated (`web_tools`) and so
/// lives there, off by default. Nested agents (`Task`/`Agent`) are
/// intentionally omitted. `Bash` is disallowed — shell execution goes
/// through `mcp__bash__run` (background tasks with structured output via
/// `hive-bash-mcp`) instead of a raw interactive shell. `TodoWrite` is
/// omitted because the todo list lives in claude's in-process session state
/// and silently evaporates on /compact or session reset — agents should
/// plan in /state notes instead. `Skill` is included so installed plugin
/// skills (`base@hyperhive` and friends) are actually invokable — without
/// it here, every `SKILL.md`'s `description` frontmatter is inert: the
/// model never sees the tool that triggers a skill, no matter how well it
/// matches the task at hand.
pub const ALLOWED_BUILTIN_TOOLS: &[&str] = &["Edit", "Glob", "Grep", "Read", "Skill", "Write"];

/// The tool groups in effect for this process, from [`TOOL_GROUPS_ENV`].
///
/// Absent, blank, or naming nothing recognisable all fall back to
/// [`ToolGroup::AGENT_DEFAULT`] — the var is written per agent by the meta
/// renderer, so "unset" is an ordinary state, not an error.
#[must_use]
pub fn effective_tool_groups() -> Vec<ToolGroup> {
    ToolGroup::parse_list(&std::env::var(TOOL_GROUPS_ENV).unwrap_or_default())
}

/// The built-in claude tools `groups` resolve to: [`ALLOWED_BUILTIN_TOOLS`]
/// plus each group's own built-ins, de-duplicated, base set first.
#[must_use]
pub fn builtin_tools_for(groups: &[ToolGroup]) -> Vec<&'static str> {
    let mut tools: Vec<&'static str> = ALLOWED_BUILTIN_TOOLS.to_vec();
    for group in groups {
        for tool in group.builtin_tools() {
            if !tools.contains(tool) {
                tools.push(tool);
            }
        }
    }
    tools
}

/// The value for claude's `--tools` flag: which built-in tools exist in this
/// session at all.
///
/// ⚠️ **Never emit this as an empty string** — not because of what an empty
/// value does, but because we don't know. Our own measurement and the
/// installed `claude --help` disagree about whether `--tools ""` means "no
/// tools" or parses as the flag being unset, and the answer is a property of
/// whichever claude release is installed, not of this code. So an empty
/// value is refused rather than relied on: the rule holds under either
/// reading, and no caller has to know which one is true today.
/// [`ALLOWED_BUILTIN_TOOLS`] is non-empty, which keeps the case from
/// arising in the first place.
///
/// ⚠️ This governs built-ins only. `mcp__*` tools are not filtered by
/// `--tools` at all; they are governed by `--strict-mcp-config` plus
/// whatever the caller renders into `--mcp-config`.
#[must_use]
pub fn builtin_tools_arg() -> String {
    builtin_tools_for(&effective_tool_groups()).join(",")
}

/// [`builtin_tools_for`] plus Claude's built-in `Bash`, granted iff `groups`
/// contains [`ToolGroup::Execution`] — the **subagent**-only `--tools`
/// resolution.
///
/// `Execution` already grants shell execution to the parent agent, via the
/// out-of-process `bash` MCP server (`mcp__bash__run`/`status`/`kill` —
/// see the variant's own doc comment). A subagent has no MCP server at all
/// by default (`docs/tools/subagent.md`), so there is no `mcp__bash__*` for
/// it to inherit that capability through; it gets Claude's own `Bash`
/// instead. The capability transfers from the parent, the mechanism it
/// arrives by does not have to match.
///
/// 🩸 Deliberately **not** folded into [`builtin_tools_for`]/[`ToolGroup::builtin_tools`]:
/// those are shared with the harness's own `--tools` (`hive-agent`'s
/// `mcp_config::allowed_tools_arg`), and the main agent must never gain
/// built-in `Bash` no matter which groups it holds — only a *subagent*
/// spawned by an `Execution`-holding parent does.
#[must_use]
pub fn subagent_builtin_tools_for(groups: &[ToolGroup]) -> Vec<&'static str> {
    let mut tools = builtin_tools_for(groups);
    if groups.contains(&ToolGroup::Execution) {
        tools.push("Bash");
    }
    tools
}

/// The value for a **subagent's** `--tools` flag: [`subagent_builtin_tools_for`]
/// resolved against [`effective_tool_groups`]. See that function for why this
/// differs from [`builtin_tools_arg`].
#[must_use]
pub fn subagent_builtin_tools_arg() -> String {
    subagent_builtin_tools_for(&effective_tool_groups()).join(",")
}

/// Named group of MCP tools an agent may be granted. The harness reads
/// `HIVE_TOOL_GROUPS` from the environment (a comma-separated list of
/// `snake_case` group names written by the meta renderer from per-agent
/// config) and expands it to the matching tool names for `--allowedTools`.
/// When the env var is absent the harness falls back to `AGENT_DEFAULT`.
/// See `docs/process/conventions.md::Tool groups`.
#[derive(
    Debug,
    Clone,
    Copy,
    PartialEq,
    Eq,
    Hash,
    Serialize,
    Deserialize,
    strum::IntoStaticStr,
    strum::EnumString,
)]
#[serde(rename_all = "snake_case")]
#[strum(serialize_all = "snake_case")]
pub enum ToolGroup {
    /// `send`, `recv`, `ack_until`
    Messaging,
    /// `get_agent_meta` (`set_status` is always-on — see `ALWAYS_ON_TOOLS`)
    Meta,
    /// `get_loose_ends`, `cancel_loose_end`, `remind`
    Inbox,
    /// `list_containers` - *(privileged)*
    Lifecycle,
    /// `request_update_meta_inputs` - *(privileged)*
    Approvals,
    /// `request_schedule_prompt`, `fire_schedule_now`, `cancel_schedule`,
    /// `edit_schedule`, `list_schedules` - *(privileged)*
    Scheduling,
    /// `create_repo` — create git repos through hive-c0re (the only path
    /// now that agents can't create them directly). Opt-in per
    /// agent so the operator controls who can spin up repos.
    Forge,
    /// Gates whether the `bash` MCP server (`mcp__bash__run`/`status`/
    /// `kill`) is rendered into the agent's config at all — see
    /// `extra_server_required_group` in `hive-agent/src/mcp_config.rs`.
    /// `tools()` returns `&[]`: this isn't a `mcp__hyperhive__*`
    /// allowlist entry, the gate lives at config-render time instead.
    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 {
    /// Parse a comma-separated [`TOOL_GROUPS_ENV`] value. Tokens are trimmed
    /// and lowercased; an unrecognised one is warned about and skipped
    /// rather than failing the whole list, so one stale name in an agent's
    /// config can't take its whole tool surface away.
    ///
    /// Returns [`AGENT_DEFAULT`](Self::AGENT_DEFAULT) when `raw` is blank or
    /// names nothing recognisable — the same fallback either way, because
    /// "the operator granted no groups" and "the var is missing" are not
    /// distinguishable here and neither should mean "no tools".
    #[must_use]
    pub fn parse_list(raw: &str) -> Vec<Self> {
        let mut groups = Vec::new();
        for token in raw.split(',') {
            let token = token.trim().to_ascii_lowercase();
            if token.is_empty() {
                continue;
            }
            match Self::from_str(&token) {
                Ok(group) => groups.push(group),
                Err(_) => {
                    tracing::warn!(token = %token, "{TOOL_GROUPS_ENV}: unknown tool group, skipping");
                }
            }
        }
        if groups.is_empty() {
            if !raw.trim().is_empty() {
                tracing::warn!(
                    "{TOOL_GROUPS_ENV} set but contained no recognised groups; \
                     falling back to AGENT_DEFAULT"
                );
            }
            return Self::AGENT_DEFAULT.to_vec();
        }
        groups
    }

    /// 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 {
            Self::Messaging => &["send", "recv", "ack_until"],
            Self::Meta => &["get_agent_meta"],
            Self::Inbox => &["get_loose_ends", "cancel_loose_end", "remind"],
            Self::Lifecycle => &["list_containers"],
            Self::Approvals => &["request_update_meta_inputs"],
            Self::Scheduling => &[
                "request_schedule_prompt",
                "fire_schedule_now",
                "cancel_schedule",
                "edit_schedule",
                "list_schedules",
            ],
            Self::Forge => &["create_repo"],
            // Both empty, for different reasons — see each variant's own
            // doc comment above. `Execution` grants the out-of-process
            // `bash` MCP server (`mcp__bash__run`/`status`/`kill`), gated
            // at config-render time by `extra_server_required_group` in
            // `hive-agent/src/mcp_config.rs`, not by this list — an
            // out-of-process server has no later enforcement point, so
            // that gate is the actual security boundary. `WebTools`
            // grants Claude built-in tools, not MCP ones; see
            // `builtin_tools()`.
            Self::Execution | Self::WebTools => &[],
        }
    }

    /// MCP tools that are always exposed regardless of which tool groups an
    /// agent is granted. `set_status` lives here because the operator
    /// dashboard depends on every agent being able to report its status
    /// chip — gating it behind a group would let a misconfigured agent go
    /// dark on the dashboard. The server-side `SetStatus` handler has no
    /// tool-group check either (only length validation), so listing it here
    /// keeps the `--allowedTools` list honest with that reality.
    ///
    /// `compact` lives here too: it's pure self-management (no cross-agent
    /// effect, no privilege), gated server-side on context usage rather
    /// than on tool groups, and every agent should be able to reach for it
    /// regardless of which optional groups it's been granted — same
    /// reasoning as `set_status`.
    ///
    /// `mark_todos_done` too (a critical bug every agent hit): it was
    /// declared as a `#[tool]` fn but never added to *any*
    /// group's [`tools`](Self::tools), including `Inbox`, so no agent could
    /// ever get it into `--allowedTools` and every call prompted for
    /// approval it can't get. Todos are pushed to an agent independent of
    /// whether it holds `Inbox` (that group only gates
    /// `get_loose_ends`/`cancel_loose_end`/`remind`), so an agent without
    /// `Inbox` could accumulate todos it can never clear — same
    /// "every agent needs this regardless of optional groups" shape as
    /// `set_status`/`compact`, not a narrower `Inbox`-only fix.
    pub const ALWAYS_ON_TOOLS: &'static [&'static str] =
        &["set_status", "compact", "mark_todos_done"];

    /// 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"],
            _ => &[],
        }
    }

    /// Default tool groups for an agent harness. Used when `HIVE_TOOL_GROUPS` is unset.
    pub const AGENT_DEFAULT: &'static [Self] =
        &[Self::Messaging, Self::Meta, Self::Inbox, Self::Execution];

    /// Convenience preset for a fully-privileged agent (all groups).
    /// Use this as a starting point in `tool-groups.json` for root/manager agents.
    pub const MANAGER_DEFAULT: &'static [Self] = &[
        Self::Messaging,
        Self::Meta,
        Self::Inbox,
        Self::Lifecycle,
        Self::Approvals,
        Self::Scheduling,
        Self::Execution,
    ];

    /// Every known tool group in a stable order. Use this to enumerate
    /// columns in the capabilities UI or any other place that needs the
    /// full list without hard-coding it at the call site.
    pub const ALL: &'static [Self] = &[
        Self::Messaging,
        Self::Meta,
        Self::Inbox,
        Self::Lifecycle,
        Self::Approvals,
        Self::Scheduling,
        Self::Forge,
        Self::Execution,
        Self::WebTools,
    ];

    /// Short human-readable description suitable for a tooltip or help text.
    #[must_use]
    pub fn description(self) -> &'static str {
        match self {
            Self::Messaging => "send, recv, ack_until — core agent communication",
            Self::Meta => {
                "get_agent_meta — identity introspection (set_status is always available)"
            }
            Self::Inbox => "get_loose_ends, cancel_loose_end, remind — self-scheduling",
            Self::Lifecycle => "list_containers — own-subtree container listing (privileged)",
            Self::Approvals => {
                "request_update_meta_inputs — operator-approved meta-flake input bumps (privileged)"
            }
            Self::Scheduling => {
                "request_schedule_prompt and related — operator-visible scheduled prompts (privileged)"
            }
            Self::Forge => {
                "create_repo — create git repos through hive-c0re (operator-gated merge)"
            }
            Self::Execution => {
                "run, status — run shell commands via mcp__bash__run / mcp__bash__status"
            }
            Self::WebTools => "WebFetch, WebSearch — Claude built-in web egress; not MCP tools",
        }
    }
}

/// Per-agent capability grants. Stored in `meta/capabilities.json`
/// (same shape as `tool-groups.json`: `{ "alice": ["read_host_journal"] }`).
/// Capabilities control system-level access hive-c0re enforces at
/// dispatch time; they are orthogonal to tool groups (which control
/// which MCP tools the harness exposes to claude).
///
/// Injected into containers as `HIVE_CAPABILITIES` (comma-separated
/// `snake_case`) via `meta::render_flake`. The harness reads this to
/// conditionally register capability-gated MCP tools so claude only
/// sees tools it can actually invoke. See `docs/process/conventions.md::Capabilities`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize, strum::IntoStaticStr)]
#[serde(rename_all = "snake_case")]
#[strum(serialize_all = "snake_case")]
pub enum Capability {
    /// Agent can lifecycle-manage the root agent (kill/start/restart)
    /// on behalf of the hive when the root has crashed. Named capability
    /// for the existing manager privilege — future topology enforcement
    /// will gate this via the capability system instead of the hardcoded
    /// `container == MANAGER_CONTAINER` check.
    ManageRootAgent,
    /// Agent can read the full host journal via `GetHostJournal`.
    /// hive-c0re checks this capability before running journalctl.
    /// MCP tool `get_host_journal` is only registered in the harness
    /// when this capability is present.
    ReadHostJournal,
}

impl Capability {
    /// Every known capability in a stable order. Use this to enumerate
    /// columns in the permissions UI or validate incoming capability strings.
    pub const ALL: &'static [Self] = &[Self::ManageRootAgent, Self::ReadHostJournal];

    /// Short human-readable description suitable for a tooltip or help text.
    #[must_use]
    pub fn description(self) -> &'static str {
        match self {
            Self::ManageRootAgent => {
                "lifecycle-manage the root/manager agent on hive crash recovery"
            }
            Self::ReadHostJournal => "read host journald via get_host_journal MCP tool",
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// The env-var spellings the meta renderer actually writes must round-trip
    /// back to groups. `strum::EnumString` and serde's `rename_all` are two
    /// independent derives over the same names; this pins them together, since
    /// the renderer writes what serde would produce and the parse is strum's.
    #[test]
    fn parse_list_accepts_the_snake_case_names_the_renderer_writes() {
        assert_eq!(
            ToolGroup::parse_list("messaging, Meta ,web_tools"),
            vec![ToolGroup::Messaging, ToolGroup::Meta, ToolGroup::WebTools]
        );
        for group in ToolGroup::ALL {
            let name: &'static str = (*group).into();
            assert_eq!(ToolGroup::parse_list(name), vec![*group], "{name}");
        }
    }

    /// Blank, absent and all-garbage are the same state as far as the tool
    /// surface is concerned: the default groups, never an empty list.
    #[test]
    fn parse_list_falls_back_to_the_agent_default_rather_than_nothing() {
        for raw in ["", "   ", ",,", "not_a_group,also_not"] {
            assert_eq!(
                ToolGroup::parse_list(raw),
                ToolGroup::AGENT_DEFAULT.to_vec(),
                "{raw:?}"
            );
        }
    }

    /// Adding groups only ever adds built-ins — the base set is in every
    /// resolution, and no group can remove one. Both `--tools` callers (the
    /// harness and the subagent daemon) rely on this to reason about "the
    /// parent's set" without re-deriving it.
    #[test]
    fn builtin_tools_are_the_base_set_plus_whatever_the_groups_add() {
        assert_eq!(
            builtin_tools_for(&[]),
            ALLOWED_BUILTIN_TOOLS.to_vec(),
            "no groups resolves to exactly the base set"
        );
        assert_eq!(
            builtin_tools_for(ToolGroup::AGENT_DEFAULT),
            ALLOWED_BUILTIN_TOOLS.to_vec(),
            "the default groups add no built-ins"
        );
        for group in ToolGroup::ALL {
            let resolved = builtin_tools_for(&[*group]);
            for base in ALLOWED_BUILTIN_TOOLS {
                assert!(resolved.contains(base), "{group:?} dropped {base}");
            }
        }
    }

    /// `web_tools` is the one group that widens the built-in set, and it is
    /// opt-in. A subagent inherits this resolution rather than a list of its
    /// own precisely so it cannot get web egress from a parent without the
    /// group.
    #[test]
    fn web_egress_is_present_only_with_the_web_tools_group() {
        let with = builtin_tools_for(&[ToolGroup::WebTools]);
        assert!(with.contains(&"WebFetch") && with.contains(&"WebSearch"));
        let without = builtin_tools_for(ToolGroup::MANAGER_DEFAULT);
        assert!(!without.contains(&"WebFetch") && !without.contains(&"WebSearch"));
    }

    /// No resolution may produce an empty `--tools` value. What an empty one
    /// means is disputed and release-dependent (see [`builtin_tools_arg`]),
    /// so this pins the rule that makes the question moot rather than any
    /// answer to it.
    #[test]
    fn no_group_combination_resolves_to_an_empty_tools_arg() {
        assert!(!ALLOWED_BUILTIN_TOOLS.is_empty());
        assert!(!builtin_tools_for(&[]).is_empty());
        assert!(!builtin_tools_for(ToolGroup::ALL).is_empty());
        assert!(!builtin_tools_arg().is_empty());
    }

    /// Built-ins are not MCP tools and the two lists must not be mixed: a
    /// `mcp__*` name in `--tools` would be silently inert, since `--tools`
    /// does not filter the MCP surface at all.
    #[test]
    fn the_builtin_list_names_no_mcp_tools() {
        for tool in builtin_tools_for(ToolGroup::ALL) {
            assert!(!tool.contains("__"), "{tool} looks like an MCP tool name");
        }
    }

    /// A subagent whose parent holds `Execution` gets Claude's own `Bash` —
    /// the parent already has shell execution (via the out-of-process
    /// `bash` MCP server), and a subagent has no MCP server of its own to
    /// inherit that through, so it gets Claude's built-in tool instead.
    #[test]
    fn subagent_gets_bash_when_parent_has_execution() {
        let tools = subagent_builtin_tools_for(&[ToolGroup::Execution]);
        assert!(tools.contains(&"Bash"));
    }

    /// 🎯 The negative case that matters: without `Execution`, a subagent
    /// must not get `Bash` either. Without this, a later refactor that
    /// grants it unconditionally would go unnoticed.
    #[test]
    fn subagent_gets_no_bash_without_execution() {
        for groups in [&[][..], &[ToolGroup::Messaging, ToolGroup::WebTools][..]] {
            let tools = subagent_builtin_tools_for(groups);
            assert!(!tools.contains(&"Bash"), "{groups:?} must not grant Bash");
        }
    }

    /// The parent (harness) resolver is untouched: `builtin_tools_for` /
    /// `builtin_tools_arg` — what `hive-agent`'s own `--tools` and
    /// `--allowedTools` are built from — never produce `Bash`, with or
    /// without `Execution`. Only the subagent-specific resolver above adds
    /// it; the operator's ruling was explicit that the main agent does not.
    #[test]
    fn parent_resolver_never_gains_bash() {
        for groups in [&[][..], &[ToolGroup::Execution][..], ToolGroup::ALL] {
            let tools = builtin_tools_for(groups);
            assert!(
                !tools.contains(&"Bash"),
                "{groups:?} must not grant Bash to the parent"
            );
        }
    }
}