release_kit/
diagnostic.rs

1//! Diagnostics as data: the closed reason vocabulary and the typed error
2//! report.
3//!
4//! An error is a value with named parts, rendered at the boundary — never
5//! a pre-formatted string assembled where the failure happened. The exit
6//! code stays the coarse machine signal; the `reason` beside it is the
7//! fine one, drawn from one closed vocabulary agents can branch on the
8//! way scripts branch on exit codes. The vocabulary is append-only: a
9//! reason is never renamed and never reused.
10
11use serde::Serialize;
12
13/// The version of the JSON diagnostic's shape.
14pub const DIAGNOSTIC_SCHEMA: &str = "rk.diagnostic/1";
15
16/// The closed reason vocabulary, the machine twin of the exit-code matrix.
17///
18/// Many reasons map to one exit code — that is the point: the code carries
19/// the category, the reason carries the instance. Classification is honest
20/// or absent: a failure nothing can classify further stays [`Reason::Io`]
21/// or [`Reason::Internal`] rather than guessing.
22#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize)]
23#[serde(rename_all = "kebab-case")]
24pub enum Reason {
25    /// Semantically invalid arguments or names.
26    Usage,
27    /// The named target does not exist or is not usable as a target.
28    TargetNotFound,
29    /// No forge could be detected from the repository's remote.
30    ForgeUndetected,
31    /// The detected or named forge is not one the binary supports.
32    ForgeUnsupported,
33    /// A prerequisite probe failed before any side effect.
34    PrerequisiteUnmet,
35    /// The forge CLI is present and not authenticated.
36    ForgeAuthentication,
37    /// The forge refused the caller's permissions.
38    ForgePermission,
39    /// The forge rate-limited the call.
40    ForgeRateLimit,
41    /// The forge failed in a way a retry can cure.
42    ForgeTemporary,
43    /// The remote state changed under the run.
44    RemoteConflict,
45    /// The command refused an action it judged destructive.
46    DestructiveRefusal,
47    /// The state found differs from what would permit the action.
48    StateDrift,
49    /// A record or document declares a schema this binary does not know.
50    UnsupportedSchema,
51    /// A mutating run could not create its journal.
52    JournalUnavailable,
53    /// A child process could not be spawned.
54    SubprocessSpawn,
55    /// A child process ran and failed without a finer classification.
56    SubprocessFailed,
57    /// Filesystem failure.
58    Io,
59    /// A defect in this binary.
60    Internal,
61    /// A hand-authored target configuration is invalid.
62    ConfigInvalid,
63    /// A registry did not answer. No live path emits it; the vocabulary
64    /// is append-only, so the word stays.
65    RegistryUnreachable,
66    /// A fetched artifact failed its verification. No live path emits
67    /// it; the vocabulary is append-only, so the word stays.
68    BundleUnverified,
69    /// A precondition did not hold before a write. No live path emits
70    /// it; the vocabulary is append-only, so the word stays.
71    PlanNotReady,
72    /// A postcondition found the target short after a write. No live
73    /// path emits it; the vocabulary is append-only, so the word stays.
74    PostconditionFailed,
75    /// Another run holds the target, and this one wrote nothing.
76    TargetBusy,
77    /// A read-only observation could not decide a step from where it ran,
78    /// and found no step wrong.
79    ObservationIncomplete,
80    /// The landing record exists and does not parse as one.
81    RecordInvalid,
82}
83
84/// Every reason, in declaration order; a test asserts against this so an
85/// addition is deliberate and a rename impossible.
86pub const REASONS: [Reason; 26] = [
87    Reason::Usage,
88    Reason::TargetNotFound,
89    Reason::ForgeUndetected,
90    Reason::ForgeUnsupported,
91    Reason::PrerequisiteUnmet,
92    Reason::ForgeAuthentication,
93    Reason::ForgePermission,
94    Reason::ForgeRateLimit,
95    Reason::ForgeTemporary,
96    Reason::RemoteConflict,
97    Reason::DestructiveRefusal,
98    Reason::StateDrift,
99    Reason::UnsupportedSchema,
100    Reason::JournalUnavailable,
101    Reason::SubprocessSpawn,
102    Reason::SubprocessFailed,
103    Reason::Io,
104    Reason::Internal,
105    Reason::ConfigInvalid,
106    Reason::RegistryUnreachable,
107    Reason::BundleUnverified,
108    Reason::PlanNotReady,
109    Reason::PostconditionFailed,
110    Reason::TargetBusy,
111    Reason::ObservationIncomplete,
112    Reason::RecordInvalid,
113];
114
115impl Reason {
116    /// The kebab-case wire form, identical to the serde rendering.
117    #[must_use]
118    pub const fn as_str(self) -> &'static str {
119        match self {
120            Self::Usage => "usage",
121            Self::TargetNotFound => "target-not-found",
122            Self::ForgeUndetected => "forge-undetected",
123            Self::ForgeUnsupported => "forge-unsupported",
124            Self::PrerequisiteUnmet => "prerequisite-unmet",
125            Self::ForgeAuthentication => "forge-authentication",
126            Self::ForgePermission => "forge-permission",
127            Self::ForgeRateLimit => "forge-rate-limit",
128            Self::ForgeTemporary => "forge-temporary",
129            Self::RemoteConflict => "remote-conflict",
130            Self::DestructiveRefusal => "destructive-refusal",
131            Self::StateDrift => "state-drift",
132            Self::UnsupportedSchema => "unsupported-schema",
133            Self::JournalUnavailable => "journal-unavailable",
134            Self::SubprocessSpawn => "subprocess-spawn",
135            Self::SubprocessFailed => "subprocess-failed",
136            Self::Io => "io",
137            Self::Internal => "internal",
138            Self::ConfigInvalid => "config-invalid",
139            Self::RegistryUnreachable => "registry-unreachable",
140            Self::BundleUnverified => "bundle-unverified",
141            Self::PlanNotReady => "plan-not-ready",
142            Self::PostconditionFailed => "postcondition-failed",
143            Self::TargetBusy => "target-busy",
144            Self::ObservationIncomplete => "observation-incomplete",
145            Self::RecordInvalid => "record-invalid",
146        }
147    }
148}
149
150/// One failure, with its parts named.
151///
152/// A hint that is not known is omitted rather than invented, so every
153/// optional field serializes only when present.
154#[derive(Debug, Clone, Serialize)]
155pub struct Diagnostic {
156    /// The shape version of the JSON rendering.
157    pub schema: &'static str,
158    /// One entry from the closed vocabulary.
159    pub reason: Reason,
160    /// What happened, one line.
161    pub message: String,
162    /// What would have had to be true.
163    #[serde(skip_serializing_if = "Option::is_none")]
164    pub expected: Option<String>,
165    /// The exact command or change that fixes it, when known.
166    #[serde(skip_serializing_if = "Option::is_none")]
167    pub action: Option<String>,
168    /// Whether rerunning as-is can succeed.
169    #[serde(skip_serializing_if = "Option::is_none")]
170    pub retry: Option<bool>,
171    /// What the run left behind, stated plainly.
172    #[serde(skip_serializing_if = "Option::is_none")]
173    pub target_state: Option<String>,
174    /// The step it happened in, where there is one.
175    #[serde(skip_serializing_if = "Option::is_none")]
176    pub step: Option<String>,
177    /// The run journal explaining it, where one was written.
178    #[serde(skip_serializing_if = "Option::is_none")]
179    pub run: Option<String>,
180}
181
182impl Diagnostic {
183    /// A diagnostic carrying only its reason and message; the builder
184    /// methods add what is actually known.
185    #[must_use]
186    pub fn new(reason: Reason, message: impl Into<String>) -> Self {
187        Self {
188            schema: DIAGNOSTIC_SCHEMA,
189            reason,
190            message: message.into(),
191            expected: None,
192            action: None,
193            retry: None,
194            target_state: None,
195            step: None,
196            run: None,
197        }
198    }
199
200    /// State what would have had to be true.
201    #[must_use]
202    pub fn expected(mut self, expected: impl Into<String>) -> Self {
203        self.expected = Some(expected.into());
204        self
205    }
206
207    /// Name the command or change that fixes it.
208    #[must_use]
209    pub fn action(mut self, action: impl Into<String>) -> Self {
210        self.action = Some(action.into());
211        self
212    }
213
214    /// State what the run left behind.
215    #[must_use]
216    pub fn target_state(mut self, state: impl Into<String>) -> Self {
217        self.target_state = Some(state.into());
218        self
219    }
220
221    /// Name the step the failure happened in.
222    #[must_use]
223    pub fn step(mut self, step: impl Into<String>) -> Self {
224        self.step = Some(step.into());
225        self
226    }
227
228    /// Name the run journal that explains the failure.
229    #[must_use]
230    pub fn run(mut self, run: impl Into<String>) -> Self {
231        self.run = Some(run.into());
232        self
233    }
234
235    /// The human rendering: the five questions in order — what happened,
236    /// what was expected, what to do, how to resume, what state the target
237    /// is in — with unknown lines absent rather than invented.
238    #[must_use]
239    pub fn render_human(&self) -> String {
240        use std::fmt::Write as _;
241        let mut text = format!("error: {}", self.message);
242        if let Some(expected) = &self.expected {
243            let _ = write!(text, "\n  expected  {expected}");
244        }
245        if let Some(action) = &self.action {
246            let _ = write!(text, "\n  next      {action}");
247        }
248        if let Some(retry) = self.retry {
249            let answer = if retry {
250                "rerunning as-is can succeed"
251            } else {
252                "rerunning as-is fails the same way"
253            };
254            let _ = write!(text, "\n  retry     {answer}");
255        }
256        if let Some(state) = &self.target_state {
257            let _ = write!(text, "\n  state     {state}");
258        }
259        if let Some(run) = &self.run {
260            let _ = write!(text, "\n  run       {run}");
261        }
262        text
263    }
264}
265
266#[cfg(test)]
267mod tests {
268    use super::{Diagnostic, REASONS, Reason};
269
270    /// The vocabulary is closed and append-only: this list is the one a
271    /// deliberate addition extends, and a rename fails here first.
272    #[test]
273    fn the_reason_vocabulary_is_closed() {
274        let wire: Vec<&str> = REASONS.iter().map(|reason| reason.as_str()).collect();
275        assert_eq!(
276            wire,
277            [
278                "usage",
279                "target-not-found",
280                "forge-undetected",
281                "forge-unsupported",
282                "prerequisite-unmet",
283                "forge-authentication",
284                "forge-permission",
285                "forge-rate-limit",
286                "forge-temporary",
287                "remote-conflict",
288                "destructive-refusal",
289                "state-drift",
290                "unsupported-schema",
291                "journal-unavailable",
292                "subprocess-spawn",
293                "subprocess-failed",
294                "io",
295                "internal",
296                "config-invalid",
297                "registry-unreachable",
298                "bundle-unverified",
299                "plan-not-ready",
300                "postcondition-failed",
301                "target-busy",
302                "observation-incomplete",
303                "record-invalid",
304            ]
305        );
306    }
307
308    #[test]
309    fn the_serde_rendering_and_the_wire_form_agree() {
310        for reason in REASONS {
311            let json = serde_json::to_string(&reason).expect("a reason serializes");
312            assert_eq!(json, format!("\"{}\"", reason.as_str()));
313        }
314    }
315
316    /// The `rk.diagnostic/1` schema, held by snapshot: a field rename or
317    /// removal fails here and becomes a schema-version bump instead of a
318    /// silent parser break at some agent.
319    #[test]
320    fn the_diagnostic_schema_snapshot_holds() {
321        let full = Diagnostic::new(Reason::StateDrift, "what happened")
322            .expected("what would have had to be true")
323            .action("the command that fixes it")
324            .target_state("what the run left behind");
325        assert_eq!(
326            serde_json::to_string(&full).expect("a diagnostic serializes"),
327            r#"{"schema":"rk.diagnostic/1","reason":"state-drift","message":"what happened","expected":"what would have had to be true","action":"the command that fixes it","target_state":"what the run left behind"}"#
328        );
329        let bare = Diagnostic::new(Reason::Io, "disk fell over");
330        assert_eq!(
331            serde_json::to_string(&bare).expect("a diagnostic serializes"),
332            r#"{"schema":"rk.diagnostic/1","reason":"io","message":"disk fell over"}"#,
333            "an unknown hint must be omitted, not serialized as null"
334        );
335    }
336
337    #[test]
338    fn the_human_rendering_answers_only_what_is_known() {
339        let bare = Diagnostic::new(Reason::Io, "disk fell over");
340        assert_eq!(bare.render_human(), "error: disk fell over");
341        let full = Diagnostic::new(Reason::StateDrift, "the target drifted")
342            .expected("a clean target")
343            .action("rk init --apply")
344            .target_state("nothing was written");
345        assert_eq!(
346            full.render_human(),
347            "error: the target drifted\n  expected  a clean target\n  next      rk init --apply\n  state     nothing was written"
348        );
349    }
350}
release_kit/diagnostic.rs

release_kit/
diagnostic.rs
