harn_vm/agent_events/tool.rs
1use serde::{Deserialize, Serialize};
2
3/// Status of a tool call. Mirrors ACP's `toolCallStatus`.
4#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
5#[serde(rename_all = "snake_case")]
6pub enum ToolCallStatus {
7 /// Dispatched by the model but not yet started.
8 Pending,
9 /// Dispatch is actively running.
10 InProgress,
11 /// Finished successfully.
12 Completed,
13 /// Finished with an error.
14 Failed,
15}
16
17impl ToolCallStatus {
18 pub const ALL: [Self; 4] = [
19 Self::Pending,
20 Self::InProgress,
21 Self::Completed,
22 Self::Failed,
23 ];
24
25 pub fn as_str(self) -> &'static str {
26 match self {
27 Self::Pending => "pending",
28 Self::InProgress => "in_progress",
29 Self::Completed => "completed",
30 Self::Failed => "failed",
31 }
32 }
33}
34
35/// Wire-level classification of a `ToolCallUpdate` failure. Pairs with the
36/// human-readable `error` string so clients can render each failure type
37/// distinctly (e.g. surface a "permission denied" badge, or a different
38/// retry affordance for `network` vs `tool_error`). The enum is
39/// deliberately extensible — `unknown` is the default when the runtime
40/// could not classify a failure.
41#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
42#[serde(rename_all = "snake_case")]
43pub enum ToolCallErrorCategory {
44 /// Host-side validation rejected the args (missing required field,
45 /// invalid type, malformed JSON).
46 SchemaValidation,
47 /// The tool ran and returned an error result (e.g. `read_file` on a
48 /// missing path) — distinguished from a transport failure.
49 ToolError,
50 /// MCP transport / server-protocol error.
51 McpServerError,
52 /// Burin Swift host bridge returned an error during dispatch.
53 HostBridgeError,
54 /// `session/request_permission` denied by the client, or a policy
55 /// rule (static or dynamic) refused the call.
56 PermissionDenied,
57 /// The harn loop detector skipped this call because the same
58 /// (tool, args) pair repeated past the configured threshold.
59 RejectedLoop,
60 /// Streaming text candidate was detected (bare `name(` or
61 /// `<tool_call>` opener) but never resolved into a parseable call:
62 /// args parsed as malformed, the heredoc body broke, the tag closed
63 /// without a balanced expression, or the stream ended mid-call.
64 /// Used by the streaming candidate detector (harn#692) to retract a
65 /// `tool_call` candidate that turned out to be prose or syntactically
66 /// broken so clients can dismiss the in-flight chip.
67 ParseAborted,
68 /// The tool exceeded its time budget.
69 Timeout,
70 /// Transient network / rate-limited / 5xx provider failure.
71 Network,
72 /// The tool was cancelled (e.g. session aborted).
73 Cancelled,
74 /// Default when classification was not performed.
75 Unknown,
76}
77
78impl ToolCallErrorCategory {
79 pub const ALL: [Self; 11] = [
80 Self::SchemaValidation,
81 Self::ToolError,
82 Self::McpServerError,
83 Self::HostBridgeError,
84 Self::PermissionDenied,
85 Self::RejectedLoop,
86 Self::ParseAborted,
87 Self::Timeout,
88 Self::Network,
89 Self::Cancelled,
90 Self::Unknown,
91 ];
92
93 pub fn as_str(self) -> &'static str {
94 match self {
95 Self::SchemaValidation => "schema_validation",
96 Self::ToolError => "tool_error",
97 Self::McpServerError => "mcp_server_error",
98 Self::HostBridgeError => "host_bridge_error",
99 Self::PermissionDenied => "permission_denied",
100 Self::RejectedLoop => "rejected_loop",
101 Self::ParseAborted => "parse_aborted",
102 Self::Timeout => "timeout",
103 Self::Network => "network",
104 Self::Cancelled => "cancelled",
105 Self::Unknown => "unknown",
106 }
107 }
108
109 /// Map an internal `ErrorCategory` (used by the VM's `VmError`
110 /// classification) onto the wire enum. The internal taxonomy is
111 /// finer-grained — several transient categories collapse onto
112 /// `Network`, and the auth/quota family becomes `HostBridgeError`
113 /// because at the tool-dispatch boundary those errors come from
114 /// the bridge transport rather than the tool itself.
115 pub fn from_internal(category: &crate::value::ErrorCategory) -> Self {
116 use crate::value::ErrorCategory as Internal;
117 match category {
118 Internal::Timeout => Self::Timeout,
119 Internal::RateLimit
120 | Internal::Overloaded
121 | Internal::ServerError
122 | Internal::TransientNetwork => Self::Network,
123 Internal::SchemaValidation | Internal::SchemaStreamAborted => Self::SchemaValidation,
124 Internal::ToolError => Self::ToolError,
125 Internal::ToolRejected => Self::PermissionDenied,
126 Internal::Cancelled => Self::Cancelled,
127 Internal::Auth
128 | Internal::EgressBlocked
129 | Internal::ChannelClosed
130 | Internal::NotFound
131 | Internal::CircuitOpen
132 | Internal::BudgetExceeded
133 | Internal::Generic => Self::HostBridgeError,
134 }
135 }
136}
137
138/// Which gate refused a tool call. Pairs with [`ToolDenial`] so host
139/// harnesses can distinguish a hard capability/policy ceiling (terminal —
140/// retrying the identical call can never succeed) from a user/host
141/// approval rejection, without re-parsing the human-readable reason
142/// string (harn#2780).
143#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Default, Serialize, Deserialize)]
144#[serde(rename_all = "snake_case")]
145pub enum DenialGate {
146 /// The tool is not in the policy's allowed-tool list.
147 ToolCeiling,
148 /// The tool requires a capability/operation the policy does not grant
149 /// (e.g. `workspace.write_text`, `process.exec`).
150 CapabilityCeiling,
151 /// The tool's side-effect level exceeds the policy ceiling
152 /// (e.g. a `process_exec` tool under a `read_only` policy).
153 SideEffectCeiling,
154 /// A `tool_arg_constraint` allow-list rejected the resolved argument
155 /// value (e.g. a `command` that does not match `cargo *`).
156 ArgConstraint,
157 /// A dynamic permission rule (`when`/`unless` predicate) denied the
158 /// call.
159 DynamicPermission,
160 /// A static approval policy decided `deny`.
161 ApprovalPolicy,
162 /// Approval was required (`ask`) but could not be requested because no
163 /// host bridge was available or the request transport failed.
164 ApprovalUnavailable,
165 /// The host/user rejected an approval request (`session/request_permission`).
166 HostRejected,
167 /// A registered pre-tool hook returned `deny`.
168 HookDeny,
169 /// Gate could not be classified.
170 #[default]
171 Unknown,
172}
173
174impl DenialGate {
175 pub const ALL: [Self; 10] = [
176 Self::ToolCeiling,
177 Self::CapabilityCeiling,
178 Self::SideEffectCeiling,
179 Self::ArgConstraint,
180 Self::DynamicPermission,
181 Self::ApprovalPolicy,
182 Self::ApprovalUnavailable,
183 Self::HostRejected,
184 Self::HookDeny,
185 Self::Unknown,
186 ];
187
188 pub fn as_str(self) -> &'static str {
189 match self {
190 Self::ToolCeiling => "tool_ceiling",
191 Self::CapabilityCeiling => "capability_ceiling",
192 Self::SideEffectCeiling => "side_effect_ceiling",
193 Self::ArgConstraint => "arg_constraint",
194 Self::DynamicPermission => "dynamic_permission",
195 Self::ApprovalPolicy => "approval_policy",
196 Self::ApprovalUnavailable => "approval_unavailable",
197 Self::HostRejected => "host_rejected",
198 Self::HookDeny => "hook_deny",
199 Self::Unknown => "unknown",
200 }
201 }
202}
203
204/// Structured record of a tool call refused at the dispatch boundary —
205/// by a capability/policy ceiling, an argument allow-list, a permission
206/// rule, an approval decision, or a pre-tool hook. Carried on the denied
207/// `tool_result` and the `PermissionDeny` transcript event so host
208/// harnesses (and the loop's own stall detector) can fail or pivot early
209/// without re-parsing human-readable command output (harn#2780). The
210/// `denied_paths` field captures any workspace paths the refused call
211/// declared, so a path-scoped denial names the offending path.
212#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
213pub struct ToolDenial {
214 /// Which gate refused the call.
215 pub gate: DenialGate,
216 /// Capability/operation that was exceeded, e.g. `workspace.read_text`
217 /// or `process.exec`, when the gate identified one.
218 #[serde(skip_serializing_if = "Option::is_none", default)]
219 pub capability: Option<String>,
220 /// Workspace paths the denied call declared, when the tool annotates
221 /// path arguments. Empty for tools that declare no paths.
222 #[serde(skip_serializing_if = "Vec::is_empty", default)]
223 pub denied_paths: Vec<String>,
224 /// Whether re-issuing the identical call could ever succeed. Capability
225 /// and side-effect ceilings, argument allow-lists, and policy/approval
226 /// denials are terminal (`false`); a host harness should fail or pivot
227 /// rather than spend another model call retrying.
228 pub retryable: bool,
229 /// Human-readable explanation — the same text the model sees in the
230 /// tool result.
231 pub reason: String,
232}
233
234impl ToolDenial {
235 /// Build a terminal denial (`retryable: false`) with no declared paths
236 /// attached yet. Every gate Harn currently enforces is terminal —
237 /// re-issuing the identical call can never succeed — so the constructor
238 /// hard-codes `retryable: false`; the field exists so a future soft
239 /// denial can set it `true`. Callers at the dispatch boundary enrich
240 /// `denied_paths` from the tool's annotated path arguments.
241 pub fn terminal(
242 gate: DenialGate,
243 capability: Option<String>,
244 reason: impl Into<String>,
245 ) -> Self {
246 Self {
247 gate,
248 capability,
249 denied_paths: Vec::new(),
250 retryable: false,
251 reason: reason.into(),
252 }
253 }
254
255 pub fn to_json(&self) -> serde_json::Value {
256 serde_json::to_value(self).unwrap_or(serde_json::Value::Null)
257 }
258}
259
260/// Where a tool actually ran. Tags `ToolCallUpdate` so clients can render
261/// "via mcp:linear" / "via host bridge" badges, attribute latency by
262/// transport, and route errors to the right surface (harn#691).
263///
264/// On the wire this serializes adjacently-tagged so the `mcp_server`
265/// case carries the configured server name. The ACP adapter rewrites
266/// unit variants as bare strings (`"harn_builtin"`, `"host_bridge"`,
267/// `"provider_native"`) and the `McpServer` case as
268/// `{"kind": "mcp_server", "serverName": "..."}` to match the protocol's
269/// camelCase convention.
270#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
271#[serde(tag = "kind", rename_all = "snake_case")]
272pub enum ToolExecutor {
273 /// VM-stdlib (`read_file`, `write_file`, `exec`, `http_*`, `mcp_*`)
274 /// or any Harn-side handler closure registered in `tools_val`.
275 HarnBuiltin,
276 /// Capability provided by the host through `HostBridge.builtin_call`
277 /// (Swift-side IDE bridge, BurinApp, BurinCLI host shells).
278 HostBridge,
279 /// Tool dispatched against a configured MCP server. Detected by the
280 /// `_mcp_server` tag that `mcp_list_tools` injects on every tool
281 /// dict before the agent loop sees it.
282 McpServer { server_name: String },
283 /// Provider-side server-side tool execution — currently OpenAI
284 /// Responses-API server tools (e.g. native `tool_search`). The
285 /// runtime never dispatches these locally; the model returns the
286 /// already-executed result inline.
287 ProviderNative,
288}