diff --git a/src/commands/scan.rs b/src/commands/scan.rs
index c71d6439..5b15c01f 100644
--- a/src/commands/scan.rs
+++ b/src/commands/scan.rs
@@ -192,6 +192,7 @@ fn is_zero_u64(v: &u64) -> bool {
     *v == 0
 }
 
+#[cfg(test)]
 impl Default for Diag {
     fn default() -> Self {
         Self {
@@ -4264,3 +4265,122 @@ mod prioritize_tests {
         assert_eq!(j1, j2, "same input should produce same output");
     }
 }
+
+#[cfg(test)]
+mod stable_hash_tests {
+    use super::*;
+    use crate::evidence::Evidence;
+    use crate::labels::Cap;
+    use crate::patterns::{FindingCategory, Severity};
+
+    fn base_diag() -> Diag {
+        Diag {
+            path: "src/handler.rs".into(),
+            line: 42,
+            col: 5,
+            severity: Severity::High,
+            id: "taint-unsanitised-flow".into(),
+            category: FindingCategory::Security,
+            path_validated: false,
+            guard_kind: None,
+            message: None,
+            labels: vec![],
+            confidence: None,
+            evidence: Some(Evidence {
+                sink_caps: Cap::SQL_QUERY.bits(),
+                ..Default::default()
+            }),
+            rank_score: None,
+            rank_reason: None,
+            suppressed: false,
+            suppression: None,
+            rollup: None,
+            finding_id: String::new(),
+            alternative_finding_ids: vec![],
+            stable_hash: 0,
+        }
+    }
+
+    #[test]
+    fn compute_stable_hash_is_deterministic() {
+        let d = base_diag();
+        let h1 = compute_stable_hash(&d);
+        let h2 = compute_stable_hash(&d);
+        assert_eq!(h1, h2);
+        assert_ne!(h1, 0);
+    }
+
+    #[test]
+    fn compute_stable_hash_sensitive_to_rule_id() {
+        let d1 = base_diag();
+        let mut d2 = base_diag();
+        d2.id = "taint-unsanitised-flow (source 5:1)".into();
+        assert_ne!(compute_stable_hash(&d1), compute_stable_hash(&d2));
+    }
+
+    #[test]
+    fn compute_stable_hash_sensitive_to_path() {
+        let d1 = base_diag();
+        let mut d2 = base_diag();
+        d2.path = "src/other.rs".into();
+        assert_ne!(compute_stable_hash(&d1), compute_stable_hash(&d2));
+    }
+
+    #[test]
+    fn compute_stable_hash_sensitive_to_line() {
+        let d1 = base_diag();
+        let mut d2 = base_diag();
+        d2.line = 43;
+        assert_ne!(compute_stable_hash(&d1), compute_stable_hash(&d2));
+    }
+
+    #[test]
+    fn compute_stable_hash_sensitive_to_col() {
+        let d1 = base_diag();
+        let mut d2 = base_diag();
+        d2.col = 6;
+        assert_ne!(compute_stable_hash(&d1), compute_stable_hash(&d2));
+    }
+
+    #[test]
+    fn compute_stable_hash_sensitive_to_sink_caps() {
+        let d1 = base_diag();
+        let mut d2 = base_diag();
+        d2.evidence = Some(Evidence {
+            sink_caps: Cap::CODE_EXEC.bits(),
+            ..Default::default()
+        });
+        assert_ne!(compute_stable_hash(&d1), compute_stable_hash(&d2));
+    }
+
+    #[test]
+    fn compute_stable_hash_collision_resistance() {
+        let d1 = Diag {
+            path: "src/a.rs".into(),
+            line: 1,
+            col: 0,
+            id: "rule-x".into(),
+            ..base_diag()
+        };
+        let d2 = Diag {
+            path: "src/b.rs".into(),
+            line: 1,
+            col: 0,
+            id: "rule-x".into(),
+            ..base_diag()
+        };
+        let d3 = Diag {
+            path: "src/a.rs".into(),
+            line: 2,
+            col: 0,
+            id: "rule-x".into(),
+            ..base_diag()
+        };
+        let h1 = compute_stable_hash(&d1);
+        let h2 = compute_stable_hash(&d2);
+        let h3 = compute_stable_hash(&d3);
+        assert_ne!(h1, h2);
+        assert_ne!(h1, h3);
+        assert_ne!(h2, h3);
+    }
+}
diff --git a/src/dynamic/corpus.rs b/src/dynamic/corpus.rs
index 050206b5..346e0b1e 100644
--- a/src/dynamic/corpus.rs
+++ b/src/dynamic/corpus.rs
@@ -71,6 +71,39 @@ pub enum Oracle {
 ///
 /// When adding a new `Cap` bit: add a row above, update this function, and
 /// bump [`CORPUS_VERSION`] if you add payload support.
+///
+/// Compile-time exhaustiveness guard: `CORPUS_SUPPORTED | CORPUS_UNSUPPORTED`
+/// must equal `Cap::all()`. Adding a new Cap bit without updating this table
+/// triggers a `const` assertion failure at build time.
+const CORPUS_SUPPORTED: u32 = Cap::SQL_QUERY.bits()
+    | Cap::CODE_EXEC.bits()
+    | Cap::FILE_IO.bits()
+    | Cap::SSRF.bits()
+    | Cap::HTML_ESCAPE.bits();
+
+const CORPUS_UNSUPPORTED: u32 = Cap::ENV_VAR.bits()
+    | Cap::SHELL_ESCAPE.bits()
+    | Cap::URL_ENCODE.bits()
+    | Cap::JSON_PARSE.bits()
+    | Cap::FMT_STRING.bits()
+    | Cap::DESERIALIZE.bits()
+    | Cap::CRYPTO.bits()
+    | Cap::UNAUTHORIZED_ID.bits()
+    | Cap::DATA_EXFIL.bits()
+    | Cap::LDAP_INJECTION.bits()
+    | Cap::XPATH_INJECTION.bits()
+    | Cap::HEADER_INJECTION.bits()
+    | Cap::OPEN_REDIRECT.bits()
+    | Cap::SSTI.bits()
+    | Cap::XXE.bits()
+    | Cap::PROTOTYPE_POLLUTION.bits();
+
+const _: () = assert!(
+    CORPUS_SUPPORTED | CORPUS_UNSUPPORTED == Cap::all().bits(),
+    "Cap bit missing from corpus coverage table; \
+     add to CORPUS_SUPPORTED or CORPUS_UNSUPPORTED and update payloads_for",
+);
+
 pub fn payloads_for(cap: Cap) -> &'static [Payload] {
     if cap.contains(Cap::SQL_QUERY) {
         return SQLI;
diff --git a/src/dynamic/spec.rs b/src/dynamic/spec.rs
index 7f53be85..7a2da868 100644
--- a/src/dynamic/spec.rs
+++ b/src/dynamic/spec.rs
@@ -376,4 +376,87 @@ mod tests {
         let s2 = HarnessSpec::from_finding(&diag).unwrap();
         assert_eq!(s1.spec_hash, s2.spec_hash);
     }
+
+    fn base_spec() -> HarnessSpec {
+        use crate::labels::Cap;
+        let mut spec = HarnessSpec {
+            finding_id: "0000000000000000".into(),
+            entry_file: "src/handler.rs".into(),
+            entry_name: "process".into(),
+            entry_kind: EntryKind::Function,
+            lang: crate::symbol::Lang::Rust,
+            toolchain_id: "rust-stable".into(),
+            payload_slot: PayloadSlot::Param(0),
+            expected_cap: Cap::SQL_QUERY,
+            constraint_hints: vec![],
+            spec_hash: String::new(),
+        };
+        spec.spec_hash = compute_spec_hash(&spec);
+        spec
+    }
+
+    #[test]
+    fn spec_hash_flips_on_entry_file() {
+        let s1 = base_spec();
+        let mut s2 = s1.clone();
+        s2.entry_file = "src/other.rs".into();
+        s2.spec_hash = compute_spec_hash(&s2);
+        assert_ne!(s1.spec_hash, s2.spec_hash, "entry_file mutation must change spec_hash");
+    }
+
+    #[test]
+    fn spec_hash_flips_on_entry_name() {
+        let s1 = base_spec();
+        let mut s2 = s1.clone();
+        s2.entry_name = "other_handler".into();
+        s2.spec_hash = compute_spec_hash(&s2);
+        assert_ne!(s1.spec_hash, s2.spec_hash, "entry_name mutation must change spec_hash");
+    }
+
+    #[test]
+    fn spec_hash_flips_on_payload_slot() {
+        let s1 = base_spec();
+        let mut s2 = s1.clone();
+        s2.payload_slot = PayloadSlot::Param(1);
+        s2.spec_hash = compute_spec_hash(&s2);
+        assert_ne!(s1.spec_hash, s2.spec_hash, "payload_slot mutation must change spec_hash");
+
+        let mut s3 = s1.clone();
+        s3.payload_slot = PayloadSlot::HttpBody;
+        s3.spec_hash = compute_spec_hash(&s3);
+        assert_ne!(s1.spec_hash, s3.spec_hash, "payload_slot tag change must change spec_hash");
+
+        let mut s4 = s1.clone();
+        s4.payload_slot = PayloadSlot::EnvVar("NYX_INPUT".into());
+        s4.spec_hash = compute_spec_hash(&s4);
+        assert_ne!(s1.spec_hash, s4.spec_hash, "EnvVar payload_slot must change spec_hash");
+    }
+
+    #[test]
+    fn spec_hash_flips_on_expected_cap() {
+        use crate::labels::Cap;
+        let s1 = base_spec();
+        let mut s2 = s1.clone();
+        s2.expected_cap = Cap::CODE_EXEC;
+        s2.spec_hash = compute_spec_hash(&s2);
+        assert_ne!(s1.spec_hash, s2.spec_hash, "expected_cap mutation must change spec_hash");
+    }
+
+    #[test]
+    fn spec_hash_flips_on_constraint_hints() {
+        let s1 = base_spec();
+        let mut s2 = s1.clone();
+        s2.constraint_hints = vec!["prefix:admin/".into()];
+        s2.spec_hash = compute_spec_hash(&s2);
+        assert_ne!(s1.spec_hash, s2.spec_hash, "constraint_hints mutation must change spec_hash");
+    }
+
+    #[test]
+    fn spec_hash_flips_on_toolchain_id() {
+        let s1 = base_spec();
+        let mut s2 = s1.clone();
+        s2.toolchain_id = "rust-nightly".into();
+        s2.spec_hash = compute_spec_hash(&s2);
+        assert_ne!(s1.spec_hash, s2.spec_hash, "toolchain_id mutation must change spec_hash");
+    }
 }
diff --git a/tests/dynamic_verify_e2e.rs b/tests/dynamic_verify_e2e.rs
new file mode 100644
index 00000000..ab94edd4
--- /dev/null
+++ b/tests/dynamic_verify_e2e.rs
@@ -0,0 +1,149 @@
+//! End-to-end integration test for the `--verify` / `verify: true` path.
+//!
+//! Phase M1 has no harness builder (`harness::build` returns `Unimplemented`),
+//! so every finding that reaches `verify_finding` collapses to
+//! `VerifyStatus::Unsupported` with `reason = BackendUnavailable`. These tests
+//! confirm that:
+//!
+//! 1. `verify_finding` returns the expected `VerifyResult` shape.
+//! 2. The JSON serialization of `VerifyResult` contains the expected fields.
+//! 3. Findings that cannot derive a spec produce `Unsupported` with a typed
+//!    reason (not `BackendUnavailable`), confirming the two code paths are
+//!    distinct.
+//!
+//! Tests are gated on `#[cfg(feature = "dynamic")]` because `verify_finding`
+//! lives in the `dynamic` module. Run with `cargo nextest run --features
+//! dynamic` to exercise them.
+
+#[cfg(feature = "dynamic")]
+mod verify_e2e {
+    use nyx_scanner::commands::scan::Diag;
+    use nyx_scanner::dynamic::verify::{verify_finding, VerifyOptions};
+    use nyx_scanner::evidence::{Confidence, Evidence, FlowStep, FlowStepKind, UnsupportedReason, VerifyStatus};
+    use nyx_scanner::labels::Cap;
+    use nyx_scanner::patterns::{FindingCategory, Severity};
+
+    fn source_step(file: &str, function: &str) -> FlowStep {
+        FlowStep {
+            step: 1,
+            kind: FlowStepKind::Source,
+            file: file.into(),
+            line: 1,
+            col: 0,
+            snippet: None,
+            variable: Some("x".into()),
+            callee: None,
+            function: Some(function.into()),
+            is_cross_file: false,
+        }
+    }
+
+    fn sink_step(file: &str) -> FlowStep {
+        FlowStep {
+            step: 2,
+            kind: FlowStepKind::Sink,
+            file: file.into(),
+            line: 10,
+            col: 0,
+            snippet: None,
+            variable: None,
+            callee: None,
+            function: None,
+            is_cross_file: false,
+        }
+    }
+
+    fn taint_diag_with_cap(cap: Cap) -> Diag {
+        Diag {
+            path: "src/handler.rs".into(),
+            line: 10,
+            col: 0,
+            severity: Severity::High,
+            id: "taint-unsanitised-flow".into(),
+            category: FindingCategory::Security,
+            path_validated: false,
+            guard_kind: None,
+            message: None,
+            labels: vec![],
+            confidence: Some(Confidence::High),
+            evidence: Some(Evidence {
+                flow_steps: vec![
+                    source_step("src/handler.rs", "handle_request"),
+                    sink_step("src/handler.rs"),
+                ],
+                sink_caps: cap.bits(),
+                ..Default::default()
+            }),
+            rank_score: None,
+            rank_reason: None,
+            suppressed: false,
+            suppression: None,
+            rollup: None,
+            finding_id: String::new(),
+            alternative_finding_ids: vec![],
+            stable_hash: 0,
+        }
+    }
+
+    /// A finding with a supported cap (SQL_QUERY) and a derivable spec reaches
+    /// `harness::build`, which returns `Unimplemented` in phase M1, producing
+    /// `VerifyStatus::Unsupported` with `reason = BackendUnavailable`.
+    #[test]
+    fn verify_finding_with_supported_cap_returns_backend_unavailable() {
+        let diag = taint_diag_with_cap(Cap::SQL_QUERY);
+        let opts = VerifyOptions::default();
+        let result = verify_finding(&diag, &opts);
+
+        assert_eq!(result.status, VerifyStatus::Unsupported);
+        assert_eq!(result.reason, Some(UnsupportedReason::BackendUnavailable));
+        assert!(result.triggered_payload.is_none());
+        assert!(result.attempts.is_empty());
+    }
+
+    /// A finding with an unsupported cap (CRYPTO has no payload corpus) reaches
+    /// `run_spec`, which returns `RunError::NoPayloadsForCap`, producing
+    /// `VerifyStatus::Unsupported` with `reason = NoPayloadsForCap`.
+    /// This is distinct from `BackendUnavailable` and tests the two code paths.
+    #[test]
+    fn verify_finding_with_unsupported_cap_returns_no_payloads() {
+        let diag = taint_diag_with_cap(Cap::CRYPTO);
+        let opts = VerifyOptions::default();
+        let result = verify_finding(&diag, &opts);
+
+        assert_eq!(result.status, VerifyStatus::Unsupported);
+        assert_eq!(result.reason, Some(UnsupportedReason::NoPayloadsForCap));
+    }
+
+    /// A low-confidence finding is rejected before spec derivation with
+    /// `reason = ConfidenceTooLow`.
+    #[test]
+    fn verify_finding_low_confidence_returns_confidence_too_low() {
+        let mut diag = taint_diag_with_cap(Cap::SQL_QUERY);
+        diag.confidence = Some(Confidence::Low);
+        let opts = VerifyOptions::default();
+        let result = verify_finding(&diag, &opts);
+
+        assert_eq!(result.status, VerifyStatus::Unsupported);
+        assert_eq!(result.reason, Some(UnsupportedReason::ConfidenceTooLow));
+    }
+
+    /// The JSON shape of `VerifyResult` for `BackendUnavailable` matches the
+    /// documented contract: `status`, `reason` present; `triggered_payload`,
+    /// `detail`, `attempts` absent (skipped by serde default).
+    #[test]
+    fn verify_result_json_shape_backend_unavailable() {
+        let diag = taint_diag_with_cap(Cap::SQL_QUERY);
+        let opts = VerifyOptions::default();
+        let result = verify_finding(&diag, &opts);
+
+        let json = serde_json::to_string(&result).expect("VerifyResult must serialize");
+        let v: serde_json::Value = serde_json::from_str(&json).expect("must be valid JSON");
+
+        assert_eq!(v["status"], "Unsupported");
+        assert_eq!(v["reason"], "BackendUnavailable");
+        assert!(v.get("triggered_payload").is_none(), "triggered_payload must be absent");
+        assert!(v.get("detail").is_none(), "detail must be absent");
+        assert!(v.get("attempts").is_none(), "attempts must be absent (empty vec skipped)");
+        assert!(v["finding_id"].is_string());
+    }
+}