areev_core/
error.rs

1use std::fmt;
2
3/// Content-addressed SHA-256 hash (32 bytes, displayed as lowercase hex).
4#[derive(Clone, Copy, PartialEq, Eq, Hash)]
5pub struct Hash([u8; 32]);
6
7impl Hash {
8    /// Create a hash from a fixed-size 32-byte array (compile-time safe).
9    pub fn from_bytes(bytes: &[u8; 32]) -> Self {
10        Hash(*bytes)
11    }
12
13    /// Create a hash from a variable-length byte slice (fallible).
14    pub fn try_from_bytes(bytes: &[u8]) -> Result<Self> {
15        if bytes.len() < 32 {
16            return Err(AreevError::Format(format!(
17                "hash requires 32 bytes, got {}",
18                bytes.len()
19            )));
20        }
21        let mut arr = [0u8; 32];
22        arr.copy_from_slice(&bytes[..32]);
23        Ok(Hash(arr))
24    }
25
26    pub fn from_hex(hex_str: &str) -> Result<Self> {
27        let bytes = hex::decode(hex_str)
28            .map_err(|e| AreevError::Format(format!("invalid hex hash: {}", e)))?;
29        if bytes.len() != 32 {
30            return Err(AreevError::Format(format!(
31                "hash must be 32 bytes, got {}",
32                bytes.len()
33            )));
34        }
35        Ok(Self::from_bytes(&bytes.try_into().unwrap()))
36    }
37
38    pub fn as_bytes(&self) -> &[u8; 32] {
39        &self.0
40    }
41
42    pub fn to_hex(&self) -> String {
43        hex::encode(self.0)
44    }
45}
46
47impl fmt::Debug for Hash {
48    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
49        write!(f, "Hash({})", &self.to_hex()[..16])
50    }
51}
52
53impl fmt::Display for Hash {
54    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
55        write!(f, "{}", self.to_hex())
56    }
57}
58
59impl serde::Serialize for Hash {
60    fn serialize<S: serde::Serializer>(
61        &self,
62        serializer: S,
63    ) -> std::result::Result<S::Ok, S::Error> {
64        serializer.serialize_str(&self.to_hex())
65    }
66}
67
68impl<'de> serde::Deserialize<'de> for Hash {
69    fn deserialize<D: serde::Deserializer<'de>>(
70        deserializer: D,
71    ) -> std::result::Result<Self, D::Error> {
72        let s = String::deserialize(deserializer)?;
73        Hash::from_hex(&s).map_err(serde::de::Error::custom)
74    }
75}
76
77/// All errors in areev-core.
78#[derive(Debug)]
79pub enum AreevError {
80    NotFound(Hash),
81    Format(String),
82    Validation(String),
83    Serialization(String),
84    ToolRenderUnsupported(String),
85    Storage(String),
86    /// Another writer holds this memory (single-writer-per-memory is
87    /// enforced, not advisory, on backends that can arbitrate it).
88    StoreBusy(String),
89    /// The connection to a backing store asks for transport encryption this
90    /// build cannot provide. Its own code because the alternative — reporting
91    /// a generic validation failure — reads as a typo in the DSN, when what
92    /// actually happened is that a *refusal to downgrade to plaintext* saved
93    /// the operator from an unencrypted connection they did not ask for.
94    TlsUnavailable(String),
95    /// A write was attempted through a handle opened with `read_only: true`
96    /// (`AreevOptions::read_only`). Refused at the store layer on BOTH
97    /// backends — on postgres this is what stands between a least-privilege
98    /// SELECT-only role and a raw `42501 permission denied`; on the embedded
99    /// backend there is no privilege system to fail against, so the store
100    /// enforces the same contract itself, which is what lets one conformance
101    /// case cover both.
102    ReadOnly(String),
103    /// A read-only open could not verify the schema/tables it expected to
104    /// find (postgres only — the embedded backend bootstraps its own file
105    /// regardless of `read_only`). Distinct from [`Storage`](Self::Storage)
106    /// because the fix differs: "schema absent" needs someone to create and
107    /// migrate it; "schema present but not initialized" needs the owning
108    /// role to open it read-write once to finish bootstrap. A read-only role
109    /// can do neither itself — that is the whole point of the least-privilege
110    /// grant — so the message says which one it is rather than surfacing the
111    /// raw permission-denied Postgres gives for `CREATE SCHEMA`/DDL.
112    ReadOnlyOpenFailed(String),
113    SupersessionConflict(Hash),
114    /// A supersession-chain walk (`Areev::supersession_chain`) did not reach
115    /// a root within the bounded hop count. Real edit histories terminate in
116    /// a handful of hops; exceeding the bound means the `supersedes` links
117    /// are corrupt (e.g. cyclic) rather than merely long, so the walk fails
118    /// loudly instead of looping the process forever.
119    SupersessionChainTooDeep(Hash),
120    /// An approximate-nearest-neighbour index was asked for on a backend that
121    /// has none. Vector recall is an exact scan on the embedded engine — there
122    /// is no ANN structure to build there, and silently doing nothing would
123    /// leave a caller believing its corpus was indexed when its latency is
124    /// still linear. Only the Postgres tier (pgvector HNSW) answers this.
125    AnnIndexUnsupported(String),
126    CryptoError(String),
127    AccumulateRetryExhausted,
128    AccumulateInternal(String),
129    AccumulateBackpressureRejected,
130    Internal(String),
131    /// A verb the session's grants don't cover (`authz::AuthzSet::check`).
132    AuthzDenied(String),
133    /// A principal name no credential authenticates.
134    AuthzUnknownPrincipal(String),
135    /// The credential map failed to load or validate (fail closed).
136    AuthzConfigInvalid(String),
137    /// A presented bearer token matched no credential. Deliberately carries
138    /// no payload: a refused secret must never reach a log line.
139    AuthzTokenUnrecognized,
140}
141
142impl AreevError {
143    /// Stable machine-readable error code in `DOMAIN-Ennn` form (see the
144    /// repo-root `ERROR_CODES.md` registry). Every `Display` string begins
145    /// with this code, so a user who reports the leading token points us at
146    /// the exact variant and subsystem. **Codes are append-only debugging
147    /// handles — never renumber or reuse an existing one.**
148    pub fn code(&self) -> &'static str {
149        match self {
150            Self::NotFound(_) => "MEM-E001",
151            Self::SupersessionConflict(_) => "MEM-E002",
152            Self::SupersessionChainTooDeep(_) => "STO-E006",
153            Self::AnnIndexUnsupported(_) => "STO-E007",
154            Self::ToolRenderUnsupported(_) => "MEM-E110",
155            Self::Format(_) => "FMT-E001",
156            Self::Serialization(_) => "FMT-E002",
157            Self::Validation(_) => "VAL-E001",
158            Self::Storage(_) => "STO-E001",
159            Self::StoreBusy(_) => "STO-E002",
160            Self::TlsUnavailable(_) => "STO-E003",
161            Self::ReadOnly(_) => "STO-E004",
162            Self::ReadOnlyOpenFailed(_) => "STO-E005",
163            Self::CryptoError(_) => "CRY-E001",
164            // These originate in CAL ACCUMULATE semantics and bubble up
165            // through the store, so they keep their CAL-domain codes.
166            Self::AccumulateRetryExhausted => "CAL-E083",
167            Self::AccumulateInternal(_) => "CAL-E084",
168            Self::AccumulateBackpressureRejected => "CAL-E085",
169            Self::Internal(_) => "SYS-E001",
170            Self::AuthzDenied(_) => "AUT-E001",
171            Self::AuthzUnknownPrincipal(_) => "AUT-E002",
172            Self::AuthzConfigInvalid(_) => "AUT-E003",
173            Self::AuthzTokenUnrecognized => "AUT-E004",
174        }
175    }
176}
177
178impl std::fmt::Display for AreevError {
179    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
180        // Invariant: every arm's message starts with `self.code()` — pinned by
181        // `code_prefixes_every_display` in the tests below.
182        match self {
183            Self::NotFound(h) => write!(f, "MEM-E001: grain not found: {h}"),
184            Self::SupersessionConflict(h) => write!(f, "MEM-E002: already superseded: {h}"),
185            Self::SupersessionChainTooDeep(h) => write!(
186                f,
187                "STO-E006: supersession chain from {h} did not terminate within the bounded walk — the supersedes links may be cyclic or corrupt"
188            ),
189            Self::AnnIndexUnsupported(m) => write!(
190                f,
191                "STO-E007: no approximate vector index on this backend: {m}"
192            ),
193            Self::ToolRenderUnsupported(m) => write!(f, "MEM-E110: tool render unsupported: {m}"),
194            Self::Format(m) => write!(f, "FMT-E001: format error: {m}"),
195            Self::Serialization(m) => write!(f, "FMT-E002: serialization error: {m}"),
196            Self::Validation(m) => write!(f, "VAL-E001: validation error: {m}"),
197            Self::Storage(m) => write!(f, "STO-E001: storage error: {m}"),
198            Self::StoreBusy(m) => write!(f, "STO-E002: store busy: {m}"),
199            Self::TlsUnavailable(m) => write!(f, "STO-E003: {m}"),
200            Self::ReadOnly(m) => write!(f, "STO-E004: refusing write on a read-only memory: {m}"),
201            Self::ReadOnlyOpenFailed(m) => write!(f, "STO-E005: {m}"),
202            Self::CryptoError(m) => write!(f, "CRY-E001: crypto error: {m}"),
203            Self::AccumulateRetryExhausted => write!(f, "CAL-E083: ACCUMULATE retry budget exhausted"),
204            Self::AccumulateInternal(m) => write!(f, "CAL-E084: ACCUMULATE internal failure: {m}"),
205            Self::AccumulateBackpressureRejected => write!(f, "CAL-E085: ACCUMULATE backpressure: inflight cap exceeded"),
206            Self::Internal(m) => write!(f, "SYS-E001: internal error: {m}"),
207            Self::AuthzDenied(m) => write!(f, "AUT-E001: authorization denied: {m}"),
208            Self::AuthzUnknownPrincipal(p) => write!(f, "AUT-E002: unknown principal: {p}"),
209            Self::AuthzConfigInvalid(m) => write!(f, "AUT-E003: {m}"),
210            Self::AuthzTokenUnrecognized => write!(f, "AUT-E004: token not recognized"),
211        }
212    }
213}
214
215impl std::error::Error for AreevError {}
216
217pub type Result<T> = std::result::Result<T, AreevError>;
218
219#[cfg(test)]
220mod error_code_tests {
221    use super::*;
222
223    /// One representative instance of every variant — extend when adding one.
224    fn all_variants() -> Vec<AreevError> {
225        let h = Hash::from_bytes(&[0u8; 32]);
226        vec![
227            AreevError::NotFound(h),
228            AreevError::SupersessionConflict(h),
229            AreevError::SupersessionChainTooDeep(h),
230            AreevError::AnnIndexUnsupported("x".into()),
231            AreevError::ToolRenderUnsupported("x".into()),
232            AreevError::Format("x".into()),
233            AreevError::Serialization("x".into()),
234            AreevError::Validation("x".into()),
235            AreevError::Storage("x".into()),
236            AreevError::StoreBusy("x".into()),
237            AreevError::TlsUnavailable("x".into()),
238            AreevError::ReadOnly("x".into()),
239            AreevError::ReadOnlyOpenFailed("x".into()),
240            AreevError::CryptoError("x".into()),
241            AreevError::AccumulateRetryExhausted,
242            AreevError::AccumulateInternal("x".into()),
243            AreevError::AccumulateBackpressureRejected,
244            AreevError::Internal("x".into()),
245            AreevError::AuthzDenied("x".into()),
246            AreevError::AuthzUnknownPrincipal("x".into()),
247            AreevError::AuthzConfigInvalid("x".into()),
248            AreevError::AuthzTokenUnrecognized,
249        ]
250    }
251
252    /// The reported code must be the leading token of the message, so a user
253    /// pasting either gives us the same handle.
254    #[test]
255    fn code_prefixes_every_display() {
256        for e in all_variants() {
257            let msg = e.to_string();
258            let code = e.code();
259            assert!(
260                msg.starts_with(&format!("{code}: ")),
261                "`{msg}` must start with its code `{code}`"
262            );
263        }
264    }
265
266    /// Every code matches the `DOMAIN-Ennn` standard (see ERROR_CODES.md):
267    /// a 3-letter uppercase domain, `-E`, then digits.
268    #[test]
269    fn codes_follow_the_repo_standard() {
270        for e in all_variants() {
271            let c = e.code();
272            let (domain, num) = c.split_once("-E").unwrap_or_else(|| panic!("bad code: {c}"));
273            assert_eq!(domain.len(), 3, "{c}: domain must be 3 letters");
274            assert!(domain.chars().all(|ch| ch.is_ascii_uppercase()), "{c}: domain uppercase");
275            assert!(!num.is_empty() && num.chars().all(|ch| ch.is_ascii_digit()), "{c}: numeric suffix");
276        }
277    }
278}
areev_core/error.rs

areev_core/
error.rs
