Add offline Cashu V3 decoding for Mission 84

backend/src/models/mission.rs

@@ -323,7 +323,7 @@ impl Mission {
             67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 => DoKind::Knowledge,
             77 | 78 => DoKind::Knowledge,
             79 | 80 | 81 | 82 | 83 => DoKind::Knowledge,
-            84 | 85 | 86 => DoKind::Knowledge,
+            85 | 86 => DoKind::Knowledge,
             87 | 88 | 89 | 90 => DoKind::Knowledge,
             91 | 93 | 94 | 95 | 96 => DoKind::Knowledge,
             97 | 98 | 99 => DoKind::Knowledge,
@@ -333,7 +333,7 @@ impl Mission {
             // your own words (103). Split out of the Knowledge run above so
             // verify_proof can require a minimum length instead of letting
             // a one-character reflection clear the mission (issue #81).
-            102 | 103 => DoKind::PasteValue,
+            84 | 102 | 103 => DoKind::PasteValue,
             106 | 107 | 108 | 109 | 110 => DoKind::Knowledge,
 
             // Action missions:
@@ -428,6 +428,15 @@ mod tests {
         }
     }
 
+    /// Mission 84 decodes a bundled Cashu sample through the paste-value
+    /// input. Its neighbours remain reading-only lessons.
+    #[test]
+    fn mission_84_is_not_shadowed_by_knowledge_arms() {
+        assert_eq!(Mission::do_kind(84), DoKind::PasteValue);
+        assert_eq!(Mission::do_kind(85), DoKind::Knowledge);
+        assert_eq!(Mission::do_kind(86), DoKind::Knowledge);
+    }
+
     /// The bar itself: every flight path carries at least one mission with a
     /// real action, except Money Basics, which is deliberately exempt
     /// because it is the conceptual opening path.
@@ -459,10 +468,11 @@ pub enum DoKind {
     /// clear a minimum length so it isn't the same "any non-empty string
     /// passes" bar as `Knowledge`. See `verify_proof`'s `PasteValue` arm.
     ///
-    /// Covers missions 102/103 only. Mission 106 also renders a paste-value
-    /// input on the frontend, but intentionally stays `Knowledge` here: it's a
-    /// numeric naira-quote input, not a reflection, so the minimum-length floor
-    /// doesn't apply.
+    /// Covers mission 84's exact decoded Cashu facts and missions 102/103's
+    /// reflections. Mission 106 also renders a paste-value input on the
+    /// frontend, but intentionally stays `Knowledge` here: it is a numeric
+    /// naira-quote input, not a reflection, so the minimum-length floor does
+    /// not apply.
     PasteValue,
     NostrIdentity,
     Invoice,

backend/src/routes/missions.rs

@@ -185,8 +185,32 @@ async fn complete_mission(
     }))
 }
 
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct CashuDecodeProof {
+    format: String,
+    mint: String,
+    amount_sats: u64,
+    proof_count: usize,
+}
+
+fn verify_cashu_decode_proof(proof: &str) -> Result<(), AppError> {
+    let decoded: CashuDecodeProof = serde_json::from_str(proof)
+        .map_err(|_| AppError::BadRequest("mission 84 requires the decoded sample facts".into()))?;
+    if decoded.format != "cashuA-v3"
+        || decoded.mint != "https://8333.space:3338"
+        || decoded.amount_sats != 10
+        || decoded.proof_count != 2
+    {
+        return Err(AppError::BadRequest(
+            "mission 84 requires the official cashuA V3 sample facts".into(),
+        ));
+    }
+    Ok(())
+}
+
 /// Minimum character count for a `DoKind::PasteValue` reflection (missions
-/// 102/103). Not tied to any protocol fact — it's a judgment call about how
+/// 102/103). Not tied to any protocol fact - it is a judgment call about how
 /// much text rules out a "no" or a single pasted character while still
 /// welcoming a short-but-real answer (a bare docs link, a one-line
 /// restatement). Deliberately well under the frontend's per-mission
@@ -221,6 +245,9 @@ async fn verify_proof(
         // one-character answer can't pass it off as substance. The message
         // is written as an invitation to say more, not a rejection.
         DoKind::PasteValue => {
+            if mission == 84 {
+                return verify_cashu_decode_proof(proof);
+            }
             if proof.chars().count() < MIN_PASTE_VALUE_LEN {
                 return Err(AppError::BadRequest(format!(
                     "say a little more: at least {MIN_PASTE_VALUE_LEN} characters, so there's something real to reflect on"

backend/tests/api.rs

@@ -742,6 +742,60 @@ fn paste_value_missions_require_more_than_a_word() {
     assert_eq!(r.status(), 200, "{}", r.text().unwrap());
 }
 
+#[test]
+fn mission_84_decode_requires_canonical_proof_and_advances() {
+    let h = Harness::start();
+    let s = create_session(&h.base, "cashu-decode-test");
+    let j = join_session(&h.base, "mina", &s.id);
+
+    for m in [31u8, 32] {
+        let r = complete(&h.base, &j.auth_token, m, "acknowledged");
+        assert_eq!(r.status(), 200, "mission {m} should succeed");
+    }
+
+    let minted: Value = client()
+        .post(format!("{}/api/ecash/mint", h.base))
+        .header("authorization", format!("Bearer {}", j.auth_token))
+        .json(&json!({ "amount_sats": 50 }))
+        .send()
+        .unwrap()
+        .json()
+        .unwrap();
+    let token = minted["token"].as_str().unwrap();
+    assert_eq!(complete(&h.base, &j.auth_token, 33, token).status(), 200);
+
+    let redeemed = client()
+        .post(format!("{}/api/ecash/redeem", h.base))
+        .header("authorization", format!("Bearer {}", j.auth_token))
+        .json(&json!({ "token": token }))
+        .send()
+        .unwrap();
+    assert_eq!(redeemed.status(), 200);
+    assert_eq!(complete(&h.base, &j.auth_token, 34, token).status(), 200);
+
+    let invalid_proofs = [
+        "acknowledged",
+        r#"{"format":"cashuA-v3","mint":"https://8333.space:3338","amount_sats":10}"#,
+        r#"{"format":"cashuA-v3","mint":"https://8333.space:3338","amount_sats":10,"proof_count":2,"extra":true}"#,
+        r#"{"format":"cashuB-v4","mint":"https://8333.space:3338","amount_sats":10,"proof_count":2}"#,
+        r#"{"format":"cashuA-v3","mint":"https://example.com","amount_sats":10,"proof_count":2}"#,
+        r#"{"format":"cashuA-v3","mint":"https://8333.space:3338","amount_sats":11,"proof_count":2}"#,
+        r#"{"format":"cashuA-v3","mint":"https://8333.space:3338","amount_sats":10,"proof_count":1}"#,
+    ];
+    for proof in invalid_proofs {
+        let r = complete(&h.base, &j.auth_token, 84, proof);
+        assert_eq!(r.status(), 400, "mission 84 accepted invalid proof: {proof}");
+    }
+
+    let canonical =
+        r#"{"format":"cashuA-v3","mint":"https://8333.space:3338","amount_sats":10,"proof_count":2}"#;
+    let r = complete(&h.base, &j.auth_token, 84, canonical);
+    assert_eq!(r.status(), 200, "{}", r.text().unwrap());
+    let v: Value = r.json().unwrap();
+    assert_eq!(v["next_mission"], 55);
+    assert_eq!(v["participant"]["current_per_tree"]["ecash"], 55);
+}
+
 #[test]
 fn proof_archive_lists_completions_in_order() {
     let h = Harness::start();