fix(crypto): log swallowed decrypt on undecryptable read-path fields

The cycle/illness/records note DTOs, the biomarker context, and the custom
mood/cycle labels each degraded an undecryptable value to a blank/generic
fallback with no signal — a key-rotation gap read as 'left blank' and the
catch was silent. Keep the fail-soft read posture (one bad row never 500s
the list) but emit a wide-event on each swallowed decrypt so a systemic
key gap surfaces. The visible per-field 'unreadable' marker in the UI is
the deferred remainder.

src/lib/cycle/custom-symptoms.ts

@@ -1,6 +1,7 @@
 import { randomUUID } from "node:crypto";
 
 import { encrypt, decrypt } from "@/lib/crypto";
+import { getEvent } from "@/lib/logging/context";
 
 import { CUSTOM_SYMPTOM_KEY_PREFIX } from "@/lib/cycle/custom-symptoms-shared";
 
@@ -52,7 +53,15 @@ export function decryptCustomLabel(encoded: string | null): string | null {
   if (!encoded) return null;
   try {
     return decrypt(encoded);
-  } catch {
+  } catch (err) {
+    // A custom label WAS stored but is undecryptable — fail soft (the caller
+    // falls back to the generic i18n label) but log it (F-CRYPTO-5) so the loss
+    // of a user-renamed symptom is not entirely silent.
+    getEvent()?.addWarning(
+      `cycle custom-label decrypt failed: ${
+        err instanceof Error ? err.message : String(err)
+      }`,
+    );
     return null;
   }
 }

src/lib/cycle/dto.ts

@@ -9,6 +9,7 @@
  * (NULL = a plain presence link).
  */
 import { decrypt } from "@/lib/crypto";
+import { getEvent } from "@/lib/logging/context";
 import type { CyclePredictionResult } from "@/lib/cycle/types";
 import type {
   CycleDayLog,
@@ -73,7 +74,16 @@ function decryptNote(notesEncrypted: string | null): string | null {
   if (!notesEncrypted) return null;
   try {
     return decrypt(notesEncrypted);
-  } catch {
+  } catch (err) {
+    // A note WAS stored but is undecryptable (key-rotation gap / corruption).
+    // Fail soft to null so one bad row never throws the day-log read, but log
+    // it (F-CRYPTO-2) so a systemic key gap surfaces instead of silently
+    // reading as an empty note.
+    getEvent()?.addWarning(
+      `cycle day-log note decrypt failed: ${
+        err instanceof Error ? err.message : String(err)
+      }`,
+    );
     return null;
   }
 }

src/lib/illness/dto.ts

@@ -10,6 +10,7 @@
  * Jackson/WURSS intensity (NULL = a plain presence link).
  */
 import { decryptFromBytes } from "@/lib/ai/coach/bytes-codec";
+import { getEvent } from "@/lib/logging/context";
 import type {
   IllnessEpisode,
   IllnessDayLog,
@@ -51,7 +52,14 @@ function decryptNote(noteEncrypted: Uint8Array | null): string | null {
   if (!noteEncrypted || noteEncrypted.byteLength === 0) return null;
   try {
     return decryptFromBytes(noteEncrypted);
-  } catch {
+  } catch (err) {
+    // Undecryptable note (key gap / corruption): fail soft to null but log it
+    // (F-CRYPTO-2) so a systemic key gap surfaces instead of reading as blank.
+    getEvent()?.addWarning(
+      `illness note decrypt failed: ${
+        err instanceof Error ? err.message : String(err)
+      }`,
+    );
     return null;
   }
 }

src/lib/labs/biomarker-store.ts

@@ -13,6 +13,7 @@ import { Buffer } from "node:buffer";
 
 import { decrypt, encrypt } from "@/lib/crypto";
 import { prisma } from "@/lib/db";
+import { getEvent } from "@/lib/logging/context";
 
 /** Encrypt a UTF-8 context note into the `Bytes` payload the schema stores. */
 export function encryptContextToBytes(
@@ -40,7 +41,15 @@ export function decryptContextSoft(buf: Uint8Array | null): string | null {
   if (!buf) return null;
   try {
     return decryptContextFromBytes(buf);
-  } catch {
+  } catch (err) {
+    // Undecryptable context (key gap / corruption): fail soft to null so one
+    // bad row never 500s the catalog list, but log it (F-CRYPTO-2) so a
+    // systemic key gap surfaces instead of masking as an empty context.
+    getEvent()?.addWarning(
+      `biomarker context decrypt failed: ${
+        err instanceof Error ? err.message : String(err)
+      }`,
+    );
     return null;
   }
 }

src/lib/mood/__tests__/custom-label-decrypt-logging.test.ts

@@ -0,0 +1,49 @@
+/**
+ * F-CRYPTO-5 — an undecryptable custom mood label fails soft (the caller falls
+ * back to the generic i18n label) but must NOT be entirely silent: a swallowed
+ * decrypt now emits a wide-event so the loss of a user-renamed tag surfaces.
+ */
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const { decryptMock, addWarningMock } = vi.hoisted(() => ({
+  decryptMock: vi.fn(),
+  addWarningMock: vi.fn(),
+}));
+
+vi.mock("@/lib/crypto", () => ({
+  decrypt: decryptMock,
+  encrypt: vi.fn(),
+}));
+vi.mock("@/lib/logging/context", () => ({
+  getEvent: () => ({ addWarning: addWarningMock }),
+}));
+
+import { decryptCustomLabel } from "../custom-tags";
+
+beforeEach(() => {
+  decryptMock.mockReset();
+  addWarningMock.mockReset();
+});
+
+describe("decryptCustomLabel", () => {
+  it("returns null without logging for a genuinely-unset label", () => {
+    expect(decryptCustomLabel(null)).toBeNull();
+    expect(addWarningMock).not.toHaveBeenCalled();
+  });
+
+  it("returns the decrypted label on success", () => {
+    decryptMock.mockReturnValue("Morning walk");
+    expect(decryptCustomLabel("cipher")).toBe("Morning walk");
+    expect(addWarningMock).not.toHaveBeenCalled();
+  });
+
+  it("fails soft to null AND logs a wide-event when the decrypt throws", () => {
+    decryptMock.mockImplementation(() => {
+      throw new Error("bad key");
+    });
+    expect(decryptCustomLabel("cipher")).toBeNull();
+    expect(addWarningMock).toHaveBeenCalledWith(
+      expect.stringContaining("custom-label decrypt failed"),
+    );
+  });
+});

src/lib/mood/custom-tags.ts

@@ -3,6 +3,7 @@ import { randomUUID } from "node:crypto";
 import { z } from "zod/v4";
 
 import { encrypt, decrypt } from "@/lib/crypto";
+import { getEvent } from "@/lib/logging/context";
 import { MOOD_TAG_ICON_NAMES } from "@/lib/mood/icon-catalog";
 
 /**
@@ -77,7 +78,15 @@ export function decryptCustomLabel(encoded: string | null): string | null {
   if (!encoded) return null;
   try {
     return decrypt(encoded);
-  } catch {
+  } catch (err) {
+    // A custom label WAS stored but is undecryptable — fail soft (the caller
+    // falls back to the generic i18n label) but log it (F-CRYPTO-5) so the loss
+    // of a user-renamed tag is not entirely silent.
+    getEvent()?.addWarning(
+      `mood custom-label decrypt failed: ${
+        err instanceof Error ? err.message : String(err)
+      }`,
+    );
     return null;
   }
 }

src/lib/records/dto.ts

@@ -8,6 +8,7 @@
  * never 500s the whole page) — the IllnessEpisode DTO precedent.
  */
 import { decryptFromBytes } from "@/lib/ai/coach/bytes-codec";
+import { getEvent } from "@/lib/logging/context";
 import type { Allergy, FamilyHistoryEntry } from "@/generated/prisma/client";
 
 export interface AllergyDTO {
@@ -39,7 +40,14 @@ function decryptOptional(buf: Uint8Array | null): string | null {
   if (!buf || buf.byteLength === 0) return null;
   try {
     return decryptFromBytes(buf);
-  } catch {
+  } catch (err) {
+    // Undecryptable payload (key gap / corruption): fail soft to null but log
+    // it (F-CRYPTO-2) so a systemic key gap surfaces instead of reading blank.
+    getEvent()?.addWarning(
+      `records field decrypt failed: ${
+        err instanceof Error ? err.message : String(err)
+      }`,
+    );
     return null;
   }
 }