diff --git a/CHANGELOG.md b/CHANGELOG.md
index acd329079..daf0b6c2c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,18 @@
 
 ## [Unreleased]
 
+## [1.28.50] — 2026-07-16 — View your ECG recordings in Insights
+
+ECG recordings synced from a compatible watch were stored but never shown. They
+now have a place in Insights: a list of your recordings, each opening the full
+waveform on a familiar ECG grid, with the date, duration, average heart rate,
+and the result your device recorded.
+
+The result shown is the one your recording device produced — HealthLog does not
+read or interpret the trace and does not provide a diagnosis. A recording is
+single-lead and for personal awareness only; if a result concerns you, a note
+alongside it points you to discuss the recording with a clinician.
+
 ## [1.28.49] — 2026-07-16 — Apple Health re-import no longer stops on a duplicate reading
 
 Re-importing a cumulative export.zip could run for several minutes and then fail
@@ -14,7 +26,7 @@ carries on. A re-import completes cleanly.
 
 ## [1.28.48] — 2026-07-16 — Security follow-ups
 
-Two fixes from the campaign's security re-verification:
+Two security fixes:
 
 - On a brand-new instance with single-sign-on configured, two people signing in
   for the very first time at the same moment could both be made admin. The
diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index ba918fbbd..402e6b32b 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.28.49
+  version: 1.28.50
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.
 
@@ -6688,6 +6688,76 @@ paths:
         "401": *a1
         "422": *a3
         "429": *a4
+  /api/insights/ecg:
+    get:
+      tags:
+        - Insights
+      summary: ECG recording list (metadata only)
+      description: "v1.28.50 — the authenticated user's ECG recordings as a cheap, index-covered metadata list (recorded time,
+        duration, sampling rate, sample count, average heart rate, lead, and the DEVICE's own rhythm classification).
+        NEVER decrypts or returns the waveform — the per-recording strip is fetched on demand from GET
+        /api/insights/ecg/{id}. Reflects only the recording device's certified on-device classification, verbatim;
+        HealthLog never re-classifies an ECG or produces a diagnosis. Data-availability-gated: an empty account returns
+        `hasRecordings: false`. Module-gated on `insights` and the operator `insightStatus` assistant surface; no LLM
+        call. Auth via cookie or Bearer."
+      responses:
+        "200":
+          description: The ECG recording list (possibly empty).
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/EcgListResponseEnvelope"
+        "401": *a1
+        "403": *a5
+        "422": *a3
+        "429": *a4
+  /api/insights/ecg/{id}:
+    get:
+      tags:
+        - Insights
+      summary: One ECG recording with waveform
+      description: v1.28.50 — one recording's decrypted waveform plus metadata and the DEVICE's verbatim classification.
+        Ownership is narrowed in the query where (`{ id, userId }`) so a cross-user read is structurally impossible; a
+        foreign or unknown id 404s (existence sealed). The waveform is AES-256-GCM at rest, decrypted through the
+        fail-closed codec. By default the ~9000-sample strip is min/max-decimated to ~2500 display points so R-wave
+        peaks survive; `?full=1` returns the raw array. HealthLog does not interpret the trace, measure intervals,
+        annotate beats, or emit a verdict of its own. Module-gated on `insights` and the operator `insightStatus`
+        assistant surface; no LLM call. `no-store`. Auth via cookie or Bearer.
+      parameters:
+        - in: path
+          name: id
+          schema:
+            type: string
+            description: The ECG recording id (cuid).
+          required: true
+          description: The ECG recording id (cuid).
+        - in: query
+          name: full
+          schema:
+            description: "`1` returns the RAW, un-decimated sample array (the true-calibration 25 mm/s · 10 mm/mV zoom view).
+              Omitted returns the min/max-decimated ~2500-point fit-to-width overview (`decimated: true`)."
+            type: string
+            const: "1"
+          description: "`1` returns the RAW, un-decimated sample array (the true-calibration 25 mm/s · 10 mm/mV zoom view).
+            Omitted returns the min/max-decimated ~2500-point fit-to-width overview (`decimated: true`)."
+      responses:
+        "200":
+          description: The recording's waveform + metadata + device classification.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/EcgDetailResponseEnvelope"
+        "401": *a1
+        "403": *a5
+        "404":
+          description: No ECG recording with that id for the authenticated user (existence sealed — a foreign id is
+            indistinguishable from a missing one).
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorEnvelope"
+        "422": *a3
+        "429": *a4
   /api/insights/correlations:
     get:
       tags:
@@ -12049,6 +12119,7 @@ components:
                   - health-status
                   - breathing
                   - labs-changes
+                  - ecg
               visible:
                 type: boolean
               order:
@@ -24709,6 +24780,199 @@ components:
       additionalProperties: false
       description: "Deterministic weight-plateau detection for users on an active GLP-1 medication: stable dose for ≥ the
         window with no weight loss beyond the threshold. Association only — carries no verdict or advice."
+    EcgListResponseEnvelope:
+      type: object
+      properties:
+        data:
+          $ref: "#/components/schemas/EcgListResponse"
+        error:
+          type: "null"
+        meta:
+          type: object
+          properties:
+            requestId:
+              type: string
+          additionalProperties: false
+      required:
+        - data
+        - error
+      additionalProperties: false
+    EcgListResponse:
+      type: object
+      properties:
+        recordings:
+          type: array
+          items:
+            $ref: "#/components/schemas/EcgRecordingListItem"
+          description: The user's ECG recordings, newest first (capped at 200).
+        hasRecordings:
+          type: boolean
+          description: False for an account with no recordings — the client un-mounts the whole ECG surface (data-availability
+            floor).
+      required:
+        - recordings
+        - hasRecordings
+      additionalProperties: false
+      description: Metadata-only ECG recording list. Never carries the waveform — the per-recording strip is fetched on demand
+        from GET /api/insights/ecg/{id}. Read-only; no LLM call. Reflects only the device's own classification, never a
+        HealthLog interpretation.
+    EcgRecordingListItem:
+      type: object
+      properties:
+        id:
+          type: string
+          description: Recording id (cuid).
+        recordedAt:
+          type: string
+          format: date-time
+          pattern: ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$
+          description: On-device recording time (the display timestamp).
+        durationSeconds:
+          anyOf:
+            - type: number
+            - type: "null"
+          description: "`sampleCount / samplingFrequency` in seconds; null when the source omitted the sampling frequency."
+        samplingFrequency:
+          type: integer
+          minimum: -9007199254740991
+          maximum: 9007199254740991
+          description: Signal sampling rate in Hz (Withings ScanWatch = 300); 0 when the source omitted it.
+        sampleCount:
+          type: integer
+          minimum: -9007199254740991
+          maximum: 9007199254740991
+          description: Number of samples in the (encrypted) waveform array.
+        averageHeartRate:
+          anyOf:
+            - type: integer
+              minimum: -9007199254740991
+              maximum: 9007199254740991
+            - type: "null"
+          description: Source-reported average heart rate (BPM) for the strip, when present.
+        lead:
+          anyOf:
+            - type: string
+            - type: "null"
+          description: Recording lead label when the source reports it; null for the single-lead ScanWatch (Lead I).
+        classification:
+          anyOf:
+            - type: string
+              enum:
+                - IRREGULAR
+                - NOT_DETECTED
+                - INCONCLUSIVE
+            - type: "null"
+          description: "The RECORDING DEVICE's own rhythm classification, surfaced verbatim: IRREGULAR (device flagged possible
+            atrial fibrillation), NOT_DETECTED (algorithm ran, nothing flagged), INCONCLUSIVE (poor signal /
+            out-of-range HR). Null when the source reported none. HealthLog never re-classifies an ECG — this is the
+            device's certified on-device result, not a HealthLog verdict."
+        source:
+          type: string
+          description: Measurement source that wrote the recording (e.g. WITHINGS).
+        hasWaveform:
+          type: boolean
+          description: True when a waveform is stored (`sampleCount > 0`); false for a verdict-only fallback event with no signal
+            to fetch.
+      required:
+        - id
+        - recordedAt
+        - durationSeconds
+        - samplingFrequency
+        - sampleCount
+        - averageHeartRate
+        - lead
+        - classification
+        - source
+        - hasWaveform
+      additionalProperties: false
+    EcgDetailResponseEnvelope:
+      type: object
+      properties:
+        data:
+          $ref: "#/components/schemas/EcgDetailResponse"
+        error:
+          type: "null"
+        meta:
+          type: object
+          properties:
+            requestId:
+              type: string
+          additionalProperties: false
+      required:
+        - data
+        - error
+      additionalProperties: false
+    EcgDetailResponse:
+      type: object
+      properties:
+        recordedAt:
+          type: string
+          format: date-time
+          pattern: ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$
+          description: On-device recording time (the display timestamp).
+        durationSeconds:
+          anyOf:
+            - type: number
+            - type: "null"
+          description: Strip duration in seconds; null when the sampling frequency was 0.
+        samplingFrequency:
+          type: integer
+          minimum: -9007199254740991
+          maximum: 9007199254740991
+          description: Signal sampling rate in Hz (300 for a ScanWatch).
+        averageHeartRate:
+          anyOf:
+            - type: integer
+              minimum: -9007199254740991
+              maximum: 9007199254740991
+            - type: "null"
+          description: Source-reported average heart rate (BPM) for the strip, when present.
+        lead:
+          anyOf:
+            - type: string
+            - type: "null"
+          description: Recording lead label when reported; null for the single-lead ScanWatch (Lead I).
+        classification:
+          anyOf:
+            - type: string
+              enum:
+                - IRREGULAR
+                - NOT_DETECTED
+                - INCONCLUSIVE
+            - type: "null"
+          description: "The RECORDING DEVICE's own rhythm classification, surfaced verbatim: IRREGULAR (device flagged possible
+            atrial fibrillation), NOT_DETECTED (algorithm ran, nothing flagged), INCONCLUSIVE (poor signal /
+            out-of-range HR). Null when the source reported none. HealthLog never re-classifies an ECG — this is the
+            device's certified on-device result, not a HealthLog verdict."
+        source:
+          type: string
+          description: Measurement source that wrote the recording.
+        samples:
+          type: array
+          items:
+            type: number
+          description: Micro-volt waveform samples. Min/max-decimated to ~2500 points by default so R-wave peaks survive the
+            fit-to-width compression; the raw array when `?full=1`. The x-position of each sample is implied by its
+            index (an overview trace, not a calibrated-time axis) unless `decimated` is false.
+        decimated:
+          type: boolean
+          description: True when `samples` was min/max-decimated for display; false when the raw array is returned (`?full=1`, or
+            a strip already at or below the display budget).
+      required:
+        - recordedAt
+        - durationSeconds
+        - samplingFrequency
+        - averageHeartRate
+        - lead
+        - classification
+        - source
+        - samples
+        - decimated
+      additionalProperties: false
+      description: One ECG recording's decrypted waveform plus metadata and the DEVICE's verbatim classification. Ownership is
+        narrowed in the query where — a foreign / unknown id 404s. The waveform is AES-256-GCM at rest, decrypted
+        through the fail-closed codec. HealthLog does not interpret the trace, measure intervals, annotate beats, or
+        emit a verdict of its own. no-store.
     CorrelationDiscoveryResponseEnvelope:
       type: object
       properties:
@@ -29665,6 +29929,7 @@ components:
                   - health-status
                   - breathing
                   - labs-changes
+                  - ecg
               visible:
                 type: boolean
               order:
diff --git a/messages/de.json b/messages/de.json
index 85b1f7bf8..ba9a11a80 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -3834,6 +3834,36 @@
         "cta": "Taille-zu-Größe-Verhältnis erfassen"
       },
       "coachPrefill": "Ich habe noch kein Taille-zu-Größe-Verhältnis erfasst — warum ist es eine nützliche Zahl, und wie halte ich es unter 0,5?"
+    },
+    "ecg": {
+      "sectionTitle": "EKG-Aufzeichnungen",
+      "sectionIntro": "Einkanal-EKG-Streifen, die dein Gerät aufgezeichnet hat. HealthLog zeigt nur die Aufzeichnung und das von deinem Gerät erstellte Ergebnis – die Kurve wird nicht gelesen oder ausgewertet.",
+      "loadError": "Deine EKG-Aufzeichnungen konnten nicht geladen werden.",
+      "backToList": "Zurück zu den Aufzeichnungen",
+      "disclaimer": "Dies ist das Ergebnis, das dein Aufzeichnungsgerät erstellt hat. HealthLog liest oder interpretiert EKG-Aufzeichnungen nicht und stellt keine Diagnose.",
+      "clinicianNote": "Wenn dich dieses Ergebnis beunruhigt, besprich diese Aufzeichnung mit einer Ärztin oder einem Arzt.",
+      "resultAttribution": "Aufgezeichnetes Ergebnis: {result}, wie vom Aufzeichnungsgerät gemeldet.",
+      "result": {
+        "irregular": "Vorhofflimmern erkannt",
+        "notDetected": "Keine Anzeichen von Vorhofflimmern",
+        "inconclusive": "Nicht eindeutige Aufzeichnung",
+        "none": "Kein Ergebnis gemeldet"
+      },
+      "meta": {
+        "recorded": "Aufgezeichnet",
+        "duration": "Dauer",
+        "lead": "Ableitung",
+        "averageHeartRate": "Durchschnittliche Herzfrequenz",
+        "samplingRate": "Abtastrate",
+        "leadSingle": "Einkanal (Ableitung I)",
+        "durationValue": "{seconds} s",
+        "bpmValue": "{bpm} bpm",
+        "hzValue": "{hz} Hz",
+        "unknown": "—"
+      },
+      "waveform": {
+        "ariaLabel": "EKG-Streifen aufgezeichnet {date}, Dauer {duration}, durchschnittliche Herzfrequenz {heartRate}, aufgezeichnetes Ergebnis: {result}."
+      }
     }
   },
   "thresholds": {
diff --git a/messages/en.json b/messages/en.json
index f7f780413..a335675f8 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -3834,6 +3834,36 @@
         "cta": "Log waist-to-height ratio"
       },
       "coachPrefill": "I haven't logged a waist-to-height ratio yet — why is it a useful number, and how do I keep it under 0.5?"
+    },
+    "ecg": {
+      "sectionTitle": "ECG recordings",
+      "sectionIntro": "Single-lead ECG strips recorded by your device. HealthLog only shows the recording and the result your device produced — it does not read or interpret the waveform.",
+      "loadError": "Could not load your ECG recordings.",
+      "backToList": "Back to recordings",
+      "disclaimer": "This is the result your recording device produced. HealthLog does not read or interpret ECG recordings and does not provide a diagnosis.",
+      "clinicianNote": "If this result concerns you, discuss this recording with a clinician.",
+      "resultAttribution": "Recorded result: {result}, as reported by the recording device.",
+      "result": {
+        "irregular": "Atrial fibrillation detected",
+        "notDetected": "No signs of atrial fibrillation",
+        "inconclusive": "Inconclusive recording",
+        "none": "No result reported"
+      },
+      "meta": {
+        "recorded": "Recorded",
+        "duration": "Duration",
+        "lead": "Lead",
+        "averageHeartRate": "Average heart rate",
+        "samplingRate": "Sampling rate",
+        "leadSingle": "Single lead (Lead I)",
+        "durationValue": "{seconds} s",
+        "bpmValue": "{bpm} bpm",
+        "hzValue": "{hz} Hz",
+        "unknown": "—"
+      },
+      "waveform": {
+        "ariaLabel": "ECG strip recorded {date}, duration {duration}, average heart rate {heartRate}, recorded result: {result}."
+      }
     }
   },
   "thresholds": {
diff --git a/messages/es.json b/messages/es.json
index 40507a47b..ad6da1321 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -3834,6 +3834,36 @@
         "cta": "Registrar índice cintura-altura"
       },
       "coachPrefill": "Aún no he registrado un índice cintura-altura: ¿por qué es un número útil y cómo lo mantengo por debajo de 0,5?"
+    },
+    "ecg": {
+      "sectionTitle": "Registros de ECG",
+      "sectionIntro": "Tiras de ECG de una sola derivación registradas por tu dispositivo. HealthLog solo muestra el registro y el resultado que produjo tu dispositivo; no lee ni interpreta la onda.",
+      "loadError": "No se pudieron cargar tus registros de ECG.",
+      "backToList": "Volver a los registros",
+      "disclaimer": "Este es el resultado que produjo tu dispositivo de registro. HealthLog no lee ni interpreta los registros de ECG y no proporciona un diagnóstico.",
+      "clinicianNote": "Si este resultado te preocupa, comenta este registro con un profesional médico.",
+      "resultAttribution": "Resultado registrado: {result}, según lo informado por el dispositivo de registro.",
+      "result": {
+        "irregular": "Fibrilación auricular detectada",
+        "notDetected": "Sin signos de fibrilación auricular",
+        "inconclusive": "Registro no concluyente",
+        "none": "Sin resultado informado"
+      },
+      "meta": {
+        "recorded": "Registrado",
+        "duration": "Duración",
+        "lead": "Derivación",
+        "averageHeartRate": "Frecuencia cardíaca media",
+        "samplingRate": "Frecuencia de muestreo",
+        "leadSingle": "Una sola derivación (derivación I)",
+        "durationValue": "{seconds} s",
+        "bpmValue": "{bpm} bpm",
+        "hzValue": "{hz} Hz",
+        "unknown": "—"
+      },
+      "waveform": {
+        "ariaLabel": "Tira de ECG registrada el {date}, duración {duration}, frecuencia cardíaca media {heartRate}, resultado registrado: {result}."
+      }
     }
   },
   "thresholds": {
diff --git a/messages/fr.json b/messages/fr.json
index 4191e0ab3..7171c27d5 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -3834,6 +3834,36 @@
         "cta": "Enregistrer le rapport taille-hauteur"
       },
       "coachPrefill": "Je n'ai pas encore enregistré de rapport taille-hauteur — pourquoi est-ce un chiffre utile, et comment le maintenir sous 0,5 ?"
+    },
+    "ecg": {
+      "sectionTitle": "Enregistrements ECG",
+      "sectionIntro": "Tracés ECG à une seule dérivation enregistrés par votre appareil. HealthLog affiche uniquement l'enregistrement et le résultat produit par votre appareil ; il ne lit ni n'interprète le tracé.",
+      "loadError": "Impossible de charger vos enregistrements ECG.",
+      "backToList": "Retour aux enregistrements",
+      "disclaimer": "Il s'agit du résultat produit par votre appareil d'enregistrement. HealthLog ne lit ni n'interprète les enregistrements ECG et ne fournit aucun diagnostic.",
+      "clinicianNote": "Si ce résultat vous préoccupe, parlez de cet enregistrement à un professionnel de santé.",
+      "resultAttribution": "Résultat enregistré : {result}, tel que signalé par l'appareil d'enregistrement.",
+      "result": {
+        "irregular": "Fibrillation auriculaire détectée",
+        "notDetected": "Aucun signe de fibrillation auriculaire",
+        "inconclusive": "Enregistrement non concluant",
+        "none": "Aucun résultat signalé"
+      },
+      "meta": {
+        "recorded": "Enregistré",
+        "duration": "Durée",
+        "lead": "Dérivation",
+        "averageHeartRate": "Fréquence cardiaque moyenne",
+        "samplingRate": "Fréquence d'échantillonnage",
+        "leadSingle": "Une seule dérivation (dérivation I)",
+        "durationValue": "{seconds} s",
+        "bpmValue": "{bpm} bpm",
+        "hzValue": "{hz} Hz",
+        "unknown": "—"
+      },
+      "waveform": {
+        "ariaLabel": "Tracé ECG enregistré le {date}, durée {duration}, fréquence cardiaque moyenne {heartRate}, résultat enregistré : {result}."
+      }
     }
   },
   "thresholds": {
diff --git a/messages/it.json b/messages/it.json
index 3cea4cbb7..7d2f4f058 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -3834,6 +3834,36 @@
         "cta": "Registra il rapporto vita-altezza"
       },
       "coachPrefill": "Non ho ancora registrato un rapporto vita-altezza — perché è un numero utile e come lo tengo sotto 0,5?"
+    },
+    "ecg": {
+      "sectionTitle": "Registrazioni ECG",
+      "sectionIntro": "Tracciati ECG a derivazione singola registrati dal tuo dispositivo. HealthLog mostra solo la registrazione e il risultato prodotto dal dispositivo; non legge né interpreta il tracciato.",
+      "loadError": "Impossibile caricare le tue registrazioni ECG.",
+      "backToList": "Torna alle registrazioni",
+      "disclaimer": "Questo è il risultato prodotto dal tuo dispositivo di registrazione. HealthLog non legge né interpreta le registrazioni ECG e non fornisce una diagnosi.",
+      "clinicianNote": "Se questo risultato ti preoccupa, parla di questa registrazione con un medico.",
+      "resultAttribution": "Risultato registrato: {result}, come riportato dal dispositivo di registrazione.",
+      "result": {
+        "irregular": "Fibrillazione atriale rilevata",
+        "notDetected": "Nessun segno di fibrillazione atriale",
+        "inconclusive": "Registrazione non conclusiva",
+        "none": "Nessun risultato riportato"
+      },
+      "meta": {
+        "recorded": "Registrato",
+        "duration": "Durata",
+        "lead": "Derivazione",
+        "averageHeartRate": "Frequenza cardiaca media",
+        "samplingRate": "Frequenza di campionamento",
+        "leadSingle": "Derivazione singola (derivazione I)",
+        "durationValue": "{seconds} s",
+        "bpmValue": "{bpm} bpm",
+        "hzValue": "{hz} Hz",
+        "unknown": "—"
+      },
+      "waveform": {
+        "ariaLabel": "Tracciato ECG registrato il {date}, durata {duration}, frequenza cardiaca media {heartRate}, risultato registrato: {result}."
+      }
     }
   },
   "thresholds": {
diff --git a/messages/pl.json b/messages/pl.json
index c0fe16053..febb2845d 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -3834,6 +3834,36 @@
         "cta": "Zapisz stosunek talii do wzrostu"
       },
       "coachPrefill": "Nie zapisałem jeszcze stosunku talii do wzrostu — dlaczego to przydatna liczba i jak utrzymać ją poniżej 0,5?"
+    },
+    "ecg": {
+      "sectionTitle": "Zapisy EKG",
+      "sectionIntro": "Jednoodprowadzeniowe zapisy EKG zarejestrowane przez Twoje urządzenie. HealthLog pokazuje tylko zapis i wynik wygenerowany przez urządzenie — nie odczytuje ani nie interpretuje przebiegu.",
+      "loadError": "Nie udało się wczytać Twoich zapisów EKG.",
+      "backToList": "Powrót do zapisów",
+      "disclaimer": "To jest wynik wygenerowany przez Twoje urządzenie rejestrujące. HealthLog nie odczytuje ani nie interpretuje zapisów EKG i nie stawia diagnozy.",
+      "clinicianNote": "Jeśli ten wynik Cię niepokoi, omów ten zapis z lekarzem.",
+      "resultAttribution": "Zarejestrowany wynik: {result}, zgodnie z informacją z urządzenia rejestrującego.",
+      "result": {
+        "irregular": "Wykryto migotanie przedsionków",
+        "notDetected": "Brak oznak migotania przedsionków",
+        "inconclusive": "Zapis niejednoznaczny",
+        "none": "Nie zgłoszono wyniku"
+      },
+      "meta": {
+        "recorded": "Zarejestrowano",
+        "duration": "Czas trwania",
+        "lead": "Odprowadzenie",
+        "averageHeartRate": "Średnie tętno",
+        "samplingRate": "Częstotliwość próbkowania",
+        "leadSingle": "Jedno odprowadzenie (odprowadzenie I)",
+        "durationValue": "{seconds} s",
+        "bpmValue": "{bpm} bpm",
+        "hzValue": "{hz} Hz",
+        "unknown": "—"
+      },
+      "waveform": {
+        "ariaLabel": "Zapis EKG zarejestrowany {date}, czas trwania {duration}, średnie tętno {heartRate}, zarejestrowany wynik: {result}."
+      }
     }
   },
   "thresholds": {
diff --git a/package.json b/package.json
index 5d0224cd0..d3bceb52b 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "healthlog",
-  "version": "1.28.49",
+  "version": "1.28.50",
   "description": "Self-hosted personal-health-tracking PWA with Withings integration, AI insights, and doctor-report PDF export.",
   "license": "PolyForm-Noncommercial-1.0.0",
   "homepage": "https://healthlog.dev",
diff --git a/public/sw.js b/public/sw.js
index 0ceaa7399..4e485b61e 100644
--- a/public/sw.js
+++ b/public/sw.js
@@ -36,7 +36,7 @@ try {
 // v1.4.38.4 → v1.4.42. Do not hand-edit; bump `package.json` and rebuild.
 const CACHE_VERSION =
   (typeof self !== "undefined" && self.__APP_VERSION__) ||
-  /* @sw-version-fallback */ "v1.28.49";
+  /* @sw-version-fallback */ "v1.28.50";
 const STATIC_CACHE = `healthlog-static-${CACHE_VERSION}`;
 const PAGE_CACHE = `healthlog-pages-${CACHE_VERSION}`;
 // v1.18.6 — read-only data cache for a curated allowlist of safe GET `/api/*`
diff --git a/src/app/api/insights/__tests__/coach-route-gate-inventory.test.ts b/src/app/api/insights/__tests__/coach-route-gate-inventory.test.ts
index 99ba58ba5..17dd78f64 100644
--- a/src/app/api/insights/__tests__/coach-route-gate-inventory.test.ts
+++ b/src/app/api/insights/__tests__/coach-route-gate-inventory.test.ts
@@ -67,6 +67,12 @@ const NON_COACH_GATED_ROUTES: ReadonlyArray<string> = [
   // the same `insightStatus` sub-flag as the assessment routes (no Coach
   // prose).
   "src/app/api/insights/rhythm-events/route.ts",
+  // v1.28.50 — ECG recording surface (list + per-recording waveform). Pure
+  // DB read of the device's own recordings + verdicts; gates on the same
+  // `insightStatus` sub-flag as the assessment routes (no Coach prose — the
+  // waveform is never interpreted).
+  "src/app/api/insights/ecg/route.ts",
+  "src/app/api/insights/ecg/[id]/route.ts",
   "src/app/api/insights/weight-status/route.ts",
 ];
 
diff --git a/src/app/api/insights/ecg/[id]/__tests__/route.test.ts b/src/app/api/insights/ecg/[id]/__tests__/route.test.ts
new file mode 100644
index 000000000..125e93b9c
--- /dev/null
+++ b/src/app/api/insights/ecg/[id]/__tests__/route.test.ts
@@ -0,0 +1,161 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { NextRequest } from "next/server";
+
+/**
+ * v1.28.50 — `GET /api/insights/ecg/[id]` (waveform detail).
+ *
+ * Load-bearing behaviour under test:
+ *   - ownership is narrowed IN THE where ({ id, userId }) so a foreign id
+ *     is null and 404s (cross-user leak structurally impossible);
+ *   - the waveform is decrypted through the real fail-closed codec
+ *     (encrypt → Bytes → route → decrypt round-trip);
+ *   - the ~9000-sample strip is min/max-decimated to ~2500 by default and
+ *     `?full=1` returns the raw array;
+ *   - the response is `no-store`.
+ */
+
+vi.mock("@/lib/db", () => ({
+  prisma: {
+    appSettings: { findUnique: vi.fn().mockResolvedValue(null) },
+    ecgRecording: { findFirst: vi.fn() },
+  },
+}));
+
+vi.mock("@/lib/modules/gate", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/lib/modules/gate")>()),
+  requireModuleEnabled: vi.fn().mockResolvedValue({ enabled: true }),
+  resolveModuleMap: vi.fn().mockResolvedValue({}),
+}));
+
+vi.mock("@/lib/auth/session", () => ({ getSession: vi.fn() }));
+vi.mock("@/lib/auth/audit", () => ({
+  auditLog: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("@/lib/logging/transports", () => ({ emitIfSampled: vi.fn() }));
+vi.mock("@/lib/db-compat", () => ({
+  ensureDbCompatibility: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("next/headers", () => ({
+  headers: vi.fn(async () => ({ get: () => null })),
+  cookies: vi.fn(async () => ({
+    get: () => undefined,
+    set: () => {},
+    delete: () => {},
+  })),
+}));
+
+import { GET } from "../route";
+import { getSession } from "@/lib/auth/session";
+import { prisma } from "@/lib/db";
+import { _resetCryptoCacheForTests } from "@/lib/crypto";
+import { encryptWaveformToBytes } from "@/lib/withings/ecg-waveform-codec";
+
+const KEY = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+
+const SESSION_OK = {
+  session: { id: "sess-1", expiresAt: new Date(Date.now() + 3_600_000) },
+  user: {
+    id: "user-1",
+    username: "testuser",
+    role: "USER" as const,
+    locale: "en",
+  },
+};
+
+type Ctx = { params: Promise<{ id: string }> };
+const callGet = GET as unknown as (
+  req: NextRequest,
+  ctx: Ctx,
+) => Promise<Response>;
+
+function makeReq(query = ""): NextRequest {
+  return new NextRequest(
+    new URL(`http://localhost/api/insights/ecg/ecg_1${query}`),
+  );
+}
+function ctx(id = "ecg_1"): Ctx {
+  return { params: Promise.resolve({ id }) };
+}
+
+function rowWith(samples: number[]) {
+  return {
+    recordedAt: new Date("2026-06-01T09:15:00.000Z"),
+    durationSeconds: 30,
+    samplingFrequency: 300,
+    averageHeartRate: 72,
+    lead: null,
+    rhythmClassification: "IRREGULAR",
+    source: "WITHINGS",
+    waveformEncrypted: encryptWaveformToBytes(samples),
+  };
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  vi.unstubAllEnvs();
+  vi.stubEnv("ENCRYPTION_KEYS", "");
+  vi.stubEnv("ENCRYPTION_ACTIVE_KEY_ID", "");
+  vi.stubEnv("ENCRYPTION_KEY", KEY);
+  _resetCryptoCacheForTests();
+  vi.mocked(prisma.appSettings.findUnique).mockResolvedValue(null as never);
+  vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+});
+
+afterEach(() => {
+  vi.unstubAllEnvs();
+  _resetCryptoCacheForTests();
+});
+
+describe("GET /api/insights/ecg/[id]", () => {
+  it("narrows ownership in the where and 404s an unknown / foreign id", async () => {
+    vi.mocked(prisma.ecgRecording.findFirst).mockResolvedValue(null as never);
+    const res = await callGet(makeReq(), ctx("ecg_x"));
+    expect(res.status).toBe(404);
+    const where = vi.mocked(prisma.ecgRecording.findFirst).mock.calls[0][0]
+      ?.where as { id: string; userId: string };
+    expect(where).toEqual({ id: "ecg_x", userId: "user-1" });
+  });
+
+  it("decrypts the waveform and min/max-decimates the ~9000-sample strip", async () => {
+    const raw = Array.from({ length: 9000 }, (_, i) =>
+      Math.round(Math.sin(i / 8) * 500),
+    );
+    raw[4500] = 9999; // an R-wave peak that must survive
+    vi.mocked(prisma.ecgRecording.findFirst).mockResolvedValue(
+      rowWith(raw) as never,
+    );
+
+    const res = await callGet(makeReq(), ctx());
+    expect(res.status).toBe(200);
+    expect(res.headers.get("Cache-Control")).toBe("no-store");
+    const body = (await res.json()) as {
+      data: {
+        samples: number[];
+        decimated: boolean;
+        classification: string;
+      };
+    };
+    expect(body.data.decimated).toBe(true);
+    expect(body.data.samples.length).toBeLessThanOrEqual(2500);
+    expect(body.data.samples.length).toBeLessThan(9000);
+    // The device verdict is surfaced verbatim.
+    expect(body.data.classification).toBe("IRREGULAR");
+    // The peak survives the decimation (min/max, never a naive stride).
+    expect(Math.max(...body.data.samples)).toBe(9999);
+  });
+
+  it("returns the raw array unchanged when ?full=1", async () => {
+    const raw = Array.from({ length: 9000 }, (_, i) => i % 17);
+    vi.mocked(prisma.ecgRecording.findFirst).mockResolvedValue(
+      rowWith(raw) as never,
+    );
+
+    const res = await callGet(makeReq("?full=1"), ctx());
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as {
+      data: { samples: number[]; decimated: boolean };
+    };
+    expect(body.data.decimated).toBe(false);
+    expect(body.data.samples).toEqual(raw);
+  });
+});
diff --git a/src/app/api/insights/ecg/[id]/route.ts b/src/app/api/insights/ecg/[id]/route.ts
new file mode 100644
index 000000000..ac0d0c31b
--- /dev/null
+++ b/src/app/api/insights/ecg/[id]/route.ts
@@ -0,0 +1,101 @@
+/**
+ * v1.28.50 — single ECG recording WITH waveform.
+ *
+ * `GET /api/insights/ecg/[id]` returns one recording's decrypted waveform
+ * plus its metadata and the DEVICE's own rhythm classification. Ownership
+ * is narrowed IN THE `where` (`{ id, userId }`) so a cross-user read is
+ * structurally impossible — a foreign or unknown id resolves to null and
+ * 404s, sealing existence exactly like the documents cache-leak fix.
+ *
+ * The waveform is AES-256-GCM at rest; it is decrypted through the
+ * existing fail-closed `decryptWaveformFromBytes` (a bad key id or a
+ * non-array payload throws rather than leaking plaintext). By default the
+ * ~9000-sample strip is min/max-decimated to ~2500 display points so the
+ * R-wave peaks survive the reduction (see `decimateMinMax`); `?full=1`
+ * returns the raw array for the true-calibration zoom view.
+ *
+ * Regulatory framing (load-bearing): the response carries the waveform,
+ * the metadata, and the device's verbatim `classification` ONLY. HealthLog
+ * does not interpret the trace, measure intervals, annotate beats, or emit
+ * a verdict of its own.
+ *
+ * Mirrors the `rhythm-events` gating: `apiHandler`, cookie OR Bearer auth,
+ * `userId` from the session, the `insights` module gate, and the
+ * `insightStatus` assistant-surface gate. No AI provider call.
+ */
+import { NextRequest } from "next/server";
+
+import { apiError, apiSuccess } from "@/lib/api-response";
+import { apiHandler, requireAuth } from "@/lib/api-handler";
+import { annotate } from "@/lib/logging/context";
+import { requireAssistantSurface } from "@/lib/feature-flags";
+import { requireModuleEnabled } from "@/lib/modules/gate";
+import { prisma } from "@/lib/db";
+import { decryptWaveformFromBytes } from "@/lib/withings/ecg-waveform-codec";
+import {
+  ECG_DISPLAY_TARGET_POINTS,
+  decimateMinMax,
+} from "@/lib/insights/ecg-decimate";
+
+export const dynamic = "force-dynamic";
+
+type RouteParams = { params: Promise<{ id: string }> };
+
+export const GET = apiHandler(
+  async (request: NextRequest, { params }: RouteParams) => {
+    const { user } = await requireAuth();
+    const m = await requireModuleEnabled(user.id, "insights");
+    if (!m.enabled) return m.response;
+    await requireAssistantSurface("insightStatus");
+
+    const { id } = await params;
+    const full = request.nextUrl.searchParams.get("full") === "1";
+
+    // Ownership narrowed in the where — a foreign / unknown id is null.
+    const row = await prisma.ecgRecording.findFirst({
+      where: { id, userId: user.id },
+      select: {
+        recordedAt: true,
+        durationSeconds: true,
+        samplingFrequency: true,
+        averageHeartRate: true,
+        lead: true,
+        rhythmClassification: true,
+        source: true,
+        waveformEncrypted: true,
+      },
+    });
+
+    if (!row) {
+      return apiError("ECG recording not found", 404);
+    }
+
+    // Fail-closed decrypt (throws on a bad key id / non-array payload).
+    const raw = decryptWaveformFromBytes(row.waveformEncrypted);
+
+    const decimated = !full && raw.length > ECG_DISPLAY_TARGET_POINTS;
+    const samples = decimated
+      ? decimateMinMax(raw, ECG_DISPLAY_TARGET_POINTS)
+      : raw;
+
+    annotate({
+      action: { name: "insights.ecg.detail" },
+      meta: { sampleCount: raw.length, decimated },
+    });
+
+    const res = apiSuccess({
+      recordedAt: row.recordedAt.toISOString(),
+      durationSeconds: row.durationSeconds,
+      samplingFrequency: row.samplingFrequency,
+      averageHeartRate: row.averageHeartRate,
+      lead: row.lead,
+      classification: row.rhythmClassification,
+      source: row.source,
+      samples,
+      decimated,
+    });
+    // Never cache a decrypted health-data waveform at any hop.
+    res.headers.set("Cache-Control", "no-store");
+    return res;
+  },
+);
diff --git a/src/app/api/insights/ecg/__tests__/route.test.ts b/src/app/api/insights/ecg/__tests__/route.test.ts
new file mode 100644
index 000000000..413465864
--- /dev/null
+++ b/src/app/api/insights/ecg/__tests__/route.test.ts
@@ -0,0 +1,144 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest } from "next/server";
+
+/**
+ * v1.28.50 — `GET /api/insights/ecg` (metadata-only recording list).
+ *
+ * Load-bearing behaviour under test: it narrows the query to the session
+ * user, NEVER selects the encrypted waveform, returns the device's own
+ * classification per row, and reports `hasRecordings: false` (the
+ * data-availability gate the UI keys off) when the user has none.
+ */
+
+vi.mock("@/lib/db", () => ({
+  prisma: {
+    appSettings: { findUnique: vi.fn().mockResolvedValue(null) },
+    ecgRecording: { findMany: vi.fn() },
+  },
+}));
+
+// Module gate mocked default-enabled; the off → 403 coverage lives in the
+// module-route-gate inventory test (the route calls requireModuleEnabled).
+vi.mock("@/lib/modules/gate", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/lib/modules/gate")>()),
+  requireModuleEnabled: vi.fn().mockResolvedValue({ enabled: true }),
+  resolveModuleMap: vi.fn().mockResolvedValue({}),
+}));
+
+vi.mock("@/lib/auth/session", () => ({ getSession: vi.fn() }));
+vi.mock("@/lib/auth/audit", () => ({
+  auditLog: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("@/lib/logging/transports", () => ({ emitIfSampled: vi.fn() }));
+vi.mock("@/lib/db-compat", () => ({
+  ensureDbCompatibility: vi.fn().mockResolvedValue(undefined),
+}));
+vi.mock("next/headers", () => ({
+  headers: vi.fn(async () => ({ get: () => null })),
+  cookies: vi.fn(async () => ({
+    get: () => undefined,
+    set: () => {},
+    delete: () => {},
+  })),
+}));
+
+import { GET } from "../route";
+import { getSession } from "@/lib/auth/session";
+import { prisma } from "@/lib/db";
+
+const SESSION_OK = {
+  session: { id: "sess-1", expiresAt: new Date(Date.now() + 3_600_000) },
+  user: {
+    id: "user-1",
+    username: "testuser",
+    role: "USER" as const,
+    locale: "en",
+  },
+};
+
+const callGet = GET as unknown as (req: NextRequest) => Promise<Response>;
+function makeReq(): NextRequest {
+  return new NextRequest(new URL("http://localhost/api/insights/ecg"));
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  vi.mocked(prisma.appSettings.findUnique).mockResolvedValue(null as never);
+  vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
+});
+
+describe("GET /api/insights/ecg", () => {
+  it("returns hasRecordings:false with an empty list when the user has none", async () => {
+    vi.mocked(prisma.ecgRecording.findMany).mockResolvedValue([] as never);
+    const res = await callGet(makeReq());
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as {
+      data: { recordings: unknown[]; hasRecordings: boolean };
+    };
+    expect(body.data.hasRecordings).toBe(false);
+    expect(body.data.recordings).toEqual([]);
+  });
+
+  it("narrows the query to the session user and never selects the waveform", async () => {
+    vi.mocked(prisma.ecgRecording.findMany).mockResolvedValue([] as never);
+    await callGet(makeReq());
+    const arg = vi.mocked(prisma.ecgRecording.findMany).mock.calls[0][0] as {
+      where: { userId: string };
+      select: Record<string, boolean>;
+    };
+    expect(arg.where.userId).toBe("user-1");
+    // The encrypted blob must never be pulled into the list read.
+    expect(arg.select.waveformEncrypted).toBeUndefined();
+    expect(arg.select.id).toBe(true);
+    expect(arg.select.rhythmClassification).toBe(true);
+  });
+
+  it("maps each row to metadata + the device verdict, flagging hasWaveform", async () => {
+    vi.mocked(prisma.ecgRecording.findMany).mockResolvedValue([
+      {
+        id: "ecg_1",
+        recordedAt: new Date("2026-06-01T09:15:00.000Z"),
+        durationSeconds: 30,
+        samplingFrequency: 300,
+        sampleCount: 9000,
+        averageHeartRate: 72,
+        lead: null,
+        rhythmClassification: "IRREGULAR",
+        source: "WITHINGS",
+      },
+      {
+        id: "ecg_2",
+        recordedAt: new Date("2026-05-01T09:15:00.000Z"),
+        durationSeconds: null,
+        samplingFrequency: 0,
+        sampleCount: 0,
+        averageHeartRate: null,
+        lead: null,
+        rhythmClassification: "NOT_DETECTED",
+        source: "WITHINGS",
+      },
+    ] as never);
+    const res = await callGet(makeReq());
+    const body = (await res.json()) as {
+      data: {
+        hasRecordings: boolean;
+        recordings: Array<{
+          id: string;
+          classification: string | null;
+          hasWaveform: boolean;
+          recordedAt: string;
+        }>;
+      };
+    };
+    expect(body.data.hasRecordings).toBe(true);
+    expect(body.data.recordings[0]).toMatchObject({
+      id: "ecg_1",
+      classification: "IRREGULAR",
+      hasWaveform: true,
+      recordedAt: "2026-06-01T09:15:00.000Z",
+    });
+    // A verdict-only fallback (sampleCount 0) reports hasWaveform:false.
+    expect(body.data.recordings[1].hasWaveform).toBe(false);
+    expect(body.data.recordings[1].classification).toBe("NOT_DETECTED");
+  });
+});
diff --git a/src/app/api/insights/ecg/route.ts b/src/app/api/insights/ecg/route.ts
new file mode 100644
index 000000000..f997721b1
--- /dev/null
+++ b/src/app/api/insights/ecg/route.ts
@@ -0,0 +1,87 @@
+/**
+ * v1.28.50 — ECG recording list route (metadata only, no waveform).
+ *
+ * `GET /api/insights/ecg` returns the authenticated user's ECG recordings
+ * as a cheap, index-covered metadata list — recorded time, duration,
+ * sampling rate, sample count, average heart rate, lead, and the DEVICE's
+ * own rhythm classification. It NEVER decrypts or returns the waveform;
+ * the per-recording strip is fetched on demand via
+ * `GET /api/insights/ecg/[id]`.
+ *
+ * Regulatory framing (load-bearing): this surface reflects ONLY the
+ * classification RESULT the recording device's certified on-device
+ * algorithm produced. HealthLog never re-classifies an ECG, never reads
+ * the waveform to form a verdict, and never produces a diagnosis. The
+ * `classification` field the client renders is the device's, verbatim.
+ *
+ * Data-availability-gated by construction: an account with no recordings
+ * gets `{ recordings: [], hasRecordings: false }`, and the client un-mounts
+ * the whole surface rather than painting an empty card.
+ *
+ * Mirrors the `rhythm-events` route gating exactly: `apiHandler` wrapper,
+ * cookie OR Bearer auth, `userId` narrowed from the session (never a query
+ * field), the `insights` module gate, and the `insightStatus`
+ * assistant-surface gate. No AI provider call — this is a pure DB read.
+ */
+import { apiSuccess } from "@/lib/api-response";
+import { apiHandler, requireAuth } from "@/lib/api-handler";
+import { annotate } from "@/lib/logging/context";
+import { requireAssistantSurface } from "@/lib/feature-flags";
+import { requireModuleEnabled } from "@/lib/modules/gate";
+import { prisma } from "@/lib/db";
+
+export const dynamic = "force-dynamic";
+
+// Defensive cap. A ScanWatch user records a handful to a few dozen strips
+// over time; this is a bound, not an expected ceiling.
+const MAX_RECORDINGS = 200;
+
+export const GET = apiHandler(async () => {
+  const { user } = await requireAuth();
+  const m = await requireModuleEnabled(user.id, "insights");
+  if (!m.enabled) return m.response;
+  await requireAssistantSurface("insightStatus");
+
+  const rows = await prisma.ecgRecording.findMany({
+    where: { userId: user.id },
+    // Everything EXCEPT `waveformEncrypted` — the list never touches the
+    // encrypted blob, so no decrypt happens on this path.
+    select: {
+      id: true,
+      recordedAt: true,
+      durationSeconds: true,
+      samplingFrequency: true,
+      sampleCount: true,
+      averageHeartRate: true,
+      lead: true,
+      rhythmClassification: true,
+      source: true,
+    },
+    orderBy: { recordedAt: "desc" },
+    take: MAX_RECORDINGS,
+  });
+
+  const recordings = rows.map((r) => ({
+    id: r.id,
+    recordedAt: r.recordedAt.toISOString(),
+    durationSeconds: r.durationSeconds,
+    samplingFrequency: r.samplingFrequency,
+    sampleCount: r.sampleCount,
+    averageHeartRate: r.averageHeartRate,
+    lead: r.lead,
+    classification: r.rhythmClassification,
+    source: r.source,
+    // A `ts-` fallback event carries a verdict but no signal to fetch.
+    hasWaveform: r.sampleCount > 0,
+  }));
+
+  annotate({
+    action: { name: "insights.ecg.list" },
+    meta: { count: recordings.length },
+  });
+
+  return apiSuccess({
+    recordings,
+    hasRecordings: recordings.length > 0,
+  });
+});
diff --git a/src/app/insights/page.tsx b/src/app/insights/page.tsx
index f80c4d125..473b782df 100644
--- a/src/app/insights/page.tsx
+++ b/src/app/insights/page.tsx
@@ -128,6 +128,17 @@ const RhythmEventsCard = dynamic(
     })),
   { ssr: false },
 );
+// v1.28.50 — ECG recording surface (waveform-backed). Deferred like the
+// other below-the-fold blocks; the section un-mounts itself when the user
+// has no recordings (`ssr: false` + its own data gate), so it carries no
+// loading placeholder of its own.
+const EcgSection = dynamic(
+  () =>
+    import("@/components/insights/ecg-section").then((mod) => ({
+      default: mod.EcgSection,
+    })),
+  { ssr: false },
+);
 // v1.25 — baseline-drift card. Un-mounts when nothing is drifting; owns its own
 // read-only `/api/insights/health-status` query.
 const HealthStatusCard = dynamic(
@@ -499,6 +510,7 @@ export default function InsightsPage() {
     "health-status": <HealthStatusCard enabled={isAuthenticated} />,
     breathing: <BreathingScreeningCard enabled={isAuthenticated} />,
     "labs-changes": <LabsChangesCard enabled={isAuthenticated} />,
+    ecg: <EcgSection enabled={isAuthenticated} />,
   };
 
   const orderedSectionIds = orderedVisibleSectionIds(layout);
diff --git a/src/components/insights/__tests__/ecg-section.test.tsx b/src/components/insights/__tests__/ecg-section.test.tsx
new file mode 100644
index 000000000..6497af8fd
--- /dev/null
+++ b/src/components/insights/__tests__/ecg-section.test.tsx
@@ -0,0 +1,183 @@
+import { describe, it, expect, vi } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+
+import { I18nProvider } from "@/lib/i18n/context";
+
+/**
+ * v1.28.50 — `<EcgSection>` / `<EcgDetail>` unit tests.
+ *
+ * The load-bearing behaviour under test:
+ *   - data-availability gating: the section un-mounts entirely when the
+ *     user has no recordings or while the payload is in flight;
+ *   - the NON-DIAGNOSTIC framing (mirrors `RhythmEventsCard`): the device's
+ *     result is shown attributed to the device, a permanent disclaimer
+ *     states HealthLog does not interpret / diagnose, and any non-normal
+ *     device result adds the "discuss with a clinician" note — while a
+ *     normal result does NOT.
+ *
+ * `useAuth` + TanStack Query are mocked and the assertions run through SSR
+ * (the suite's node environment has no DOM), exactly like the sibling
+ * `rhythm-events-card` test.
+ */
+
+vi.mock("@/hooks/use-auth", () => ({
+  useAuth: vi.fn(() => ({ isAuthenticated: true, user: null })),
+}));
+
+const useQueryMock = vi.fn();
+vi.mock("@tanstack/react-query", () => ({
+  useQuery: (opts: unknown) => useQueryMock(opts),
+}));
+
+const { EcgSection, EcgDetail } = await import("../ecg-section");
+
+interface EcgRecordingListItem {
+  id: string;
+  recordedAt: string;
+  durationSeconds: number | null;
+  samplingFrequency: number;
+  sampleCount: number;
+  averageHeartRate: number | null;
+  lead: string | null;
+  classification: "IRREGULAR" | "NOT_DETECTED" | "INCONCLUSIVE" | null;
+  source: string;
+  hasWaveform: boolean;
+}
+
+const IRREGULAR_REC: EcgRecordingListItem = {
+  id: "ecg_1",
+  recordedAt: "2026-06-01T09:15:00.000Z",
+  durationSeconds: 30,
+  samplingFrequency: 300,
+  sampleCount: 9000,
+  averageHeartRate: 72,
+  lead: null,
+  classification: "IRREGULAR",
+  source: "WITHINGS",
+  hasWaveform: true,
+};
+
+const NORMAL_REC: EcgRecordingListItem = {
+  ...IRREGULAR_REC,
+  id: "ecg_2",
+  classification: "NOT_DETECTED",
+};
+
+const DETAIL = {
+  recordedAt: "2026-06-01T09:15:00.000Z",
+  durationSeconds: 30,
+  samplingFrequency: 300,
+  averageHeartRate: 72,
+  lead: null,
+  classification: "IRREGULAR" as const,
+  source: "WITHINGS",
+  samples: [0, 10, -5, 40, -20, 5, 0],
+  decimated: true,
+};
+
+function renderSection(
+  data:
+    { recordings: EcgRecordingListItem[]; hasRecordings: boolean } | undefined,
+) {
+  useQueryMock.mockReturnValue({ data, isLoading: false });
+  return renderToStaticMarkup(
+    <I18nProvider initialLocale="en">
+      <EcgSection />
+    </I18nProvider>,
+  );
+}
+
+function renderDetail(
+  recording: EcgRecordingListItem,
+  resultLabel: string | null,
+) {
+  useQueryMock.mockReturnValue({ data: DETAIL, isLoading: false });
+  return renderToStaticMarkup(
+    <I18nProvider initialLocale="en">
+      <EcgDetail
+        recording={recording}
+        resultLabel={resultLabel}
+        onBack={() => {}}
+      />
+    </I18nProvider>,
+  );
+}
+
+describe("<EcgSection>", () => {
+  it("renders nothing before the payload resolves", () => {
+    useQueryMock.mockReturnValue({ data: undefined, isLoading: true });
+    const html = renderToStaticMarkup(
+      <I18nProvider initialLocale="en">
+        <EcgSection />
+      </I18nProvider>,
+    );
+    expect(html).toBe("");
+  });
+
+  it("renders nothing when the user has no recordings (data-availability gate)", () => {
+    const html = renderSection({ recordings: [], hasRecordings: false });
+    expect(html).toBe("");
+  });
+
+  it("renders the recording list with a device-result label per row", () => {
+    const html = renderSection({
+      recordings: [IRREGULAR_REC, NORMAL_REC],
+      hasRecordings: true,
+    });
+    expect(html).toContain('data-slot="ecg-card"');
+    expect(html).toContain('data-slot="ecg-list"');
+    const rows = (html.match(/data-slot="ecg-row"/g) ?? []).length;
+    expect(rows).toBe(2);
+    expect(html).toContain("Atrial fibrillation detected");
+    expect(html).toContain("No signs of atrial fibrillation");
+  });
+
+  it("shows the permanent non-diagnostic disclaimer on the list", () => {
+    const html = renderSection({
+      recordings: [IRREGULAR_REC],
+      hasRecordings: true,
+    });
+    expect(html).toContain('data-slot="ecg-disclaimer"');
+    expect(html).toContain(
+      "HealthLog does not read or interpret ECG recordings",
+    );
+    expect(html).toContain("does not provide a diagnosis");
+  });
+});
+
+describe("<EcgDetail> — non-diagnostic framing", () => {
+  it("attributes the result to the recording device and draws the waveform", () => {
+    const html = renderDetail(IRREGULAR_REC, "Atrial fibrillation detected");
+    expect(html).toContain('data-slot="ecg-detail"');
+    expect(html).toContain('data-slot="ecg-result"');
+    // Load-bearing: the verdict is the device's, attributed to the device.
+    expect(html).toContain("as reported by the recording device");
+    expect(html).toContain("Atrial fibrillation detected");
+    // The waveform strip is rendered.
+    expect(html).toContain('data-slot="ecg-trace"');
+    // And the permanent disclaimer is present here too.
+    expect(html).toContain('data-slot="ecg-disclaimer"');
+  });
+
+  it("adds the 'discuss with a clinician' note on a non-normal result", () => {
+    const html = renderDetail(IRREGULAR_REC, "Atrial fibrillation detected");
+    expect(html).toContain('data-slot="ecg-clinician-note"');
+    expect(html).toContain("discuss this recording with a clinician");
+  });
+
+  it("adds the clinician note for an INCONCLUSIVE result", () => {
+    const html = renderDetail(
+      { ...IRREGULAR_REC, classification: "INCONCLUSIVE" },
+      "Inconclusive recording",
+    );
+    expect(html).toContain('data-slot="ecg-clinician-note"');
+  });
+
+  it("does NOT add the clinician note for a normal (not-detected) result", () => {
+    const html = renderDetail(NORMAL_REC, "No signs of atrial fibrillation");
+    expect(html).not.toContain('data-slot="ecg-clinician-note"');
+    // But the disclaimer + device attribution are still present.
+    expect(html).toContain('data-slot="ecg-disclaimer"');
+    expect(html).toContain("as reported by the recording device");
+  });
+});
diff --git a/src/components/insights/__tests__/ecg-waveform.test.tsx b/src/components/insights/__tests__/ecg-waveform.test.tsx
new file mode 100644
index 000000000..968c7188f
--- /dev/null
+++ b/src/components/insights/__tests__/ecg-waveform.test.tsx
@@ -0,0 +1,54 @@
+import { describe, it, expect } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+
+import { I18nProvider } from "@/lib/i18n/context";
+import { EcgWaveform } from "../ecg-waveform";
+
+/**
+ * v1.28.50 — `<EcgWaveform>` SVG unit tests.
+ *
+ * The component draws the raw trace and nothing else: a single `<path>`
+ * over a grid `<pattern>`, labelled as a whole image whose accessible name
+ * carries the DEVICE's result verbatim. No interpretation, no annotation.
+ */
+
+function render(props: Partial<Parameters<typeof EcgWaveform>[0]> = {}) {
+  return renderToStaticMarkup(
+    <I18nProvider initialLocale="en">
+      <EcgWaveform
+        samples={[0, 10, -5, 40, -20, 5, 0]}
+        recordedAt="2026-06-01T09:15:00.000Z"
+        durationSeconds={30}
+        averageHeartRate={72}
+        resultLabel="Atrial fibrillation detected"
+        {...props}
+      />
+    </I18nProvider>,
+  );
+}
+
+describe("<EcgWaveform>", () => {
+  it("renders a single trace path and the ECG grid pattern", () => {
+    const html = render();
+    expect(html).toContain('data-slot="ecg-waveform"');
+    expect(html).toContain('data-slot="ecg-trace"');
+    // A polyline d-string, not per-point elements.
+    expect(html).toMatch(/<path[^>]*d="M0/);
+    expect(html).toContain("<pattern");
+  });
+
+  it("exposes role=img with an accessible label carrying the device result", () => {
+    const html = render();
+    expect(html).toContain('role="img"');
+    expect(html).toContain("aria-label");
+    // The device's verdict is folded into the whole-image label verbatim.
+    expect(html).toContain("Atrial fibrillation detected");
+    expect(html).toContain("72 bpm");
+  });
+
+  it("renders no trace path for an empty sample array", () => {
+    const html = render({ samples: [] });
+    expect(html).toContain('data-slot="ecg-waveform"');
+    expect(html).not.toContain('data-slot="ecg-trace"');
+  });
+});
diff --git a/src/components/insights/ecg-section.tsx b/src/components/insights/ecg-section.tsx
new file mode 100644
index 000000000..324846d49
--- /dev/null
+++ b/src/components/insights/ecg-section.tsx
@@ -0,0 +1,356 @@
+"use client";
+
+import { useState } from "react";
+import { useQuery } from "@tanstack/react-query";
+import { Activity, ChevronLeft, HeartPulse, Info } from "lucide-react";
+
+import { useAuth } from "@/hooks/use-auth";
+import { queryKeys } from "@/lib/query-keys";
+import { apiGet } from "@/lib/api/api-fetch";
+import { useTranslations, useFormatters } from "@/lib/i18n/context";
+import { cn } from "@/lib/utils";
+import { SectionHeading } from "@/components/insights/section-heading";
+import { EcgWaveform } from "@/components/insights/ecg-waveform";
+
+/**
+ * v1.28.50 — ECG recording surface (list → detail).
+ *
+ * Renders the user's ECG recordings synced from a single-lead device
+ * (Withings ScanWatch today): a list of strips, each opening a detail view
+ * with the `EcgWaveform` trace, the recording metadata, and the DEVICE's
+ * own classification.
+ *
+ * NON-DIAGNOSTIC (load-bearing, do not soften — mirrors `RhythmEventsCard`):
+ * the surface shows only the waveform (raw data), the metadata, and the
+ * recording device's own result, attributed unambiguously to the device
+ * ("Recorded result: …, as reported by the recording device"). HealthLog
+ * generates NO interpretation of the waveform — no measured intervals, no
+ * beat/P/QRS/T annotation, no risk score, no verdict of its own. A
+ * permanent, non-dismissible disclaimer states this, and any non-normal
+ * device result additionally carries a "discuss with a clinician" note.
+ * All copy renders as plain React text children (no markdown library — the
+ * standing XSS rule).
+ *
+ * Data-availability-gated: the section un-mounts entirely (`return null`)
+ * when the user has no recordings — never an empty / alarming card.
+ */
+
+type EcgClassification = "IRREGULAR" | "NOT_DETECTED" | "INCONCLUSIVE" | null;
+
+interface EcgRecordingListItem {
+  id: string;
+  recordedAt: string;
+  durationSeconds: number | null;
+  samplingFrequency: number;
+  sampleCount: number;
+  averageHeartRate: number | null;
+  lead: string | null;
+  classification: EcgClassification;
+  source: string;
+  hasWaveform: boolean;
+}
+
+interface EcgListResponse {
+  recordings: EcgRecordingListItem[];
+  hasRecordings: boolean;
+}
+
+interface EcgDetailResponse {
+  recordedAt: string;
+  durationSeconds: number | null;
+  samplingFrequency: number;
+  averageHeartRate: number | null;
+  lead: string | null;
+  classification: EcgClassification;
+  source: string;
+  samples: number[];
+  decimated: boolean;
+}
+
+/** The device verdict, surfaced verbatim and attributed to the device. */
+const RESULT_LABEL_KEYS: Record<string, string> = {
+  IRREGULAR: "insights.ecg.result.irregular",
+  NOT_DETECTED: "insights.ecg.result.notDetected",
+  INCONCLUSIVE: "insights.ecg.result.inconclusive",
+};
+
+/** Non-normal device results trigger the "discuss with a clinician" note. */
+function isNonNormal(classification: EcgClassification): boolean {
+  return classification === "IRREGULAR" || classification === "INCONCLUSIVE";
+}
+
+interface EcgSectionProps {
+  enabled?: boolean;
+  className?: string;
+}
+
+export function EcgSection({ enabled = true, className }: EcgSectionProps) {
+  const { isAuthenticated } = useAuth();
+  const { t } = useTranslations();
+  const fmt = useFormatters();
+  const [selectedId, setSelectedId] = useState<string | null>(null);
+
+  const { data, isLoading } = useQuery({
+    queryKey: queryKeys.insightsEcgList(),
+    queryFn: async () => {
+      try {
+        return await apiGet<EcgListResponse>("/api/insights/ecg");
+      } catch {
+        throw new Error(t("insights.ecg.loadError"));
+      }
+    },
+    enabled: enabled && isAuthenticated,
+  });
+
+  // Data-availability gate — never paint an empty card.
+  if (isLoading || !data || !data.hasRecordings) return null;
+
+  const selected =
+    selectedId != null
+      ? (data.recordings.find((r) => r.id === selectedId) ?? null)
+      : null;
+
+  function resultLabel(classification: EcgClassification): string | null {
+    if (!classification) return null;
+    const key = RESULT_LABEL_KEYS[classification];
+    return key ? t(key) : null;
+  }
+
+  return (
+    <section
+      data-slot="ecg-section"
+      aria-label={t("insights.ecg.sectionTitle")}
+      className={cn("space-y-3", className)}
+    >
+      <SectionHeading icon={Activity} title={t("insights.ecg.sectionTitle")} />
+      <div
+        data-slot="ecg-card"
+        className="bg-card border-border space-y-4 rounded-xl border p-4 md:p-6"
+      >
+        {selected ? (
+          <EcgDetail
+            recording={selected}
+            resultLabel={resultLabel(selected.classification)}
+            onBack={() => setSelectedId(null)}
+          />
+        ) : (
+          <>
+            <p className="text-muted-foreground text-sm">
+              {t("insights.ecg.sectionIntro")}
+            </p>
+            <ol data-slot="ecg-list" className="space-y-3">
+              {data.recordings.map((rec) => {
+                const label = resultLabel(rec.classification);
+                const rowInner = (
+                  <>
+                    <span className="bg-muted text-muted-foreground mt-0.5 flex size-8 shrink-0 items-center justify-center rounded-full">
+                      <HeartPulse className="size-4" />
+                    </span>
+                    <div className="min-w-0 flex-1 space-y-0.5">
+                      <p className="text-foreground text-sm font-medium">
+                        {fmt.dateTime(new Date(rec.recordedAt))}
+                      </p>
+                      {label && (
+                        <p
+                          data-slot="ecg-row-result"
+                          className="text-muted-foreground text-sm"
+                        >
+                          {label}
+                        </p>
+                      )}
+                      {rec.averageHeartRate != null && (
+                        <p className="text-muted-foreground text-xs">
+                          {t("insights.ecg.meta.bpmValue", {
+                            bpm: rec.averageHeartRate,
+                          })}
+                        </p>
+                      )}
+                    </div>
+                  </>
+                );
+                return (
+                  <li
+                    key={rec.id}
+                    data-slot="ecg-row"
+                    data-classification={rec.classification ?? "NONE"}
+                    className="border-border/60 border-b pb-3 last:border-b-0 last:pb-0"
+                  >
+                    {rec.hasWaveform ? (
+                      <button
+                        type="button"
+                        onClick={() => setSelectedId(rec.id)}
+                        className="hover:bg-muted/40 -m-1 flex w-full items-start gap-3 rounded-md p-1 text-left transition-colors"
+                      >
+                        {rowInner}
+                      </button>
+                    ) : (
+                      <div className="flex items-start gap-3">{rowInner}</div>
+                    )}
+                  </li>
+                );
+              })}
+            </ol>
+
+            {/* Load-bearing regulatory disclaimer — permanent,
+              non-dismissible. Plain React text children (no markdown). */}
+            <EcgDisclaimer />
+          </>
+        )}
+      </div>
+    </section>
+  );
+}
+
+/**
+ * The detail view: waveform + metadata + device-attributed result +
+ * permanent disclaimer + clinician note on a non-normal device result.
+ * Exported so the non-diagnostic framing can be unit-tested directly.
+ */
+export function EcgDetail({
+  recording,
+  resultLabel,
+  onBack,
+}: {
+  recording: EcgRecordingListItem;
+  resultLabel: string | null;
+  onBack: () => void;
+}) {
+  const { t } = useTranslations();
+  const fmt = useFormatters();
+
+  const { data: detail, isLoading } = useQuery({
+    queryKey: queryKeys.insightsEcgDetail(recording.id, false),
+    queryFn: async () => {
+      try {
+        return await apiGet<EcgDetailResponse>(
+          `/api/insights/ecg/${recording.id}`,
+        );
+      } catch {
+        throw new Error(t("insights.ecg.loadError"));
+      }
+    },
+  });
+
+  const nonNormal = isNonNormal(recording.classification);
+  const leadLabel = recording.lead ?? t("insights.ecg.meta.leadSingle");
+  const durationLabel =
+    recording.durationSeconds != null
+      ? t("insights.ecg.meta.durationValue", {
+          seconds: Math.round(recording.durationSeconds),
+        })
+      : t("insights.ecg.meta.unknown");
+
+  return (
+    <div data-slot="ecg-detail" className="space-y-4">
+      <button
+        type="button"
+        onClick={onBack}
+        className="text-muted-foreground hover:text-foreground -ml-1 flex items-center gap-1 text-sm transition-colors"
+      >
+        <ChevronLeft className="size-4" />
+        {t("insights.ecg.backToList")}
+      </button>
+
+      {/* The DEVICE's result, attributed to the device. This is the ONLY
+        verdict shown — HealthLog produces none. */}
+      {resultLabel && (
+        <p
+          data-slot="ecg-result"
+          className="text-foreground text-sm font-medium"
+        >
+          {t("insights.ecg.resultAttribution", { result: resultLabel })}
+        </p>
+      )}
+
+      {isLoading || !detail ? (
+        <div
+          data-slot="ecg-waveform-skeleton"
+          className="bg-muted/40 h-40 w-full animate-pulse rounded-lg motion-reduce:animate-none"
+        />
+      ) : (
+        <EcgWaveform
+          samples={detail.samples}
+          recordedAt={detail.recordedAt}
+          durationSeconds={detail.durationSeconds}
+          averageHeartRate={detail.averageHeartRate}
+          resultLabel={resultLabel}
+        />
+      )}
+
+      <dl
+        data-slot="ecg-meta"
+        className="grid grid-cols-2 gap-x-4 gap-y-2 text-sm sm:grid-cols-3"
+      >
+        <MetaItem
+          label={t("insights.ecg.meta.recorded")}
+          value={fmt.dateTime(new Date(recording.recordedAt))}
+        />
+        <MetaItem
+          label={t("insights.ecg.meta.duration")}
+          value={durationLabel}
+        />
+        <MetaItem label={t("insights.ecg.meta.lead")} value={leadLabel} />
+        <MetaItem
+          label={t("insights.ecg.meta.averageHeartRate")}
+          value={
+            recording.averageHeartRate != null
+              ? t("insights.ecg.meta.bpmValue", {
+                  bpm: recording.averageHeartRate,
+                })
+              : t("insights.ecg.meta.unknown")
+          }
+        />
+        <MetaItem
+          label={t("insights.ecg.meta.samplingRate")}
+          value={
+            recording.samplingFrequency > 0
+              ? t("insights.ecg.meta.hzValue", {
+                  hz: recording.samplingFrequency,
+                })
+              : t("insights.ecg.meta.unknown")
+          }
+        />
+      </dl>
+
+      {/* "Discuss with a clinician" — only on a non-normal device result. */}
+      {nonNormal && (
+        <p
+          data-slot="ecg-clinician-note"
+          className="text-foreground text-sm font-medium"
+        >
+          {t("insights.ecg.clinicianNote")}
+        </p>
+      )}
+
+      <EcgDisclaimer />
+    </div>
+  );
+}
+
+function MetaItem({ label, value }: { label: string; value: string }) {
+  return (
+    <div className="space-y-0.5">
+      <dt className="text-muted-foreground text-xs">{label}</dt>
+      <dd className="text-foreground">{value}</dd>
+    </div>
+  );
+}
+
+/**
+ * The permanent, non-dismissible non-diagnostic disclaimer. States that the
+ * displayed result is the device's and that HealthLog does not read,
+ * interpret, or diagnose ECG recordings.
+ */
+function EcgDisclaimer() {
+  const { t } = useTranslations();
+  return (
+    <div
+      data-slot="ecg-disclaimer"
+      role="note"
+      className="bg-muted/50 text-muted-foreground flex items-start gap-2 rounded-lg p-3 text-xs"
+    >
+      <Info className="mt-0.5 size-4 shrink-0" aria-hidden="true" />
+      <p>{t("insights.ecg.disclaimer")}</p>
+    </div>
+  );
+}
diff --git a/src/components/insights/ecg-waveform.tsx b/src/components/insights/ecg-waveform.tsx
new file mode 100644
index 000000000..3779c7642
--- /dev/null
+++ b/src/components/insights/ecg-waveform.tsx
@@ -0,0 +1,188 @@
+"use client";
+
+import { useId, useMemo } from "react";
+
+import { useTranslations, useFormatters } from "@/lib/i18n/context";
+import { cn } from "@/lib/utils";
+
+/**
+ * v1.28.50 — purpose-built SVG ECG waveform strip.
+ *
+ * A raw single-lead ECG strip is thousands of micro-volt samples. This is
+ * rendered as ONE `<path>` over a classic ECG grid `<pattern>` — NOT
+ * Recharts, which builds a per-point React element tree and janks at this
+ * point count. A hand-computed polyline `d`-string is one DOM node,
+ * renders instantly, re-scales cheaply, is crisp at any zoom, prints
+ * cleanly (doctor report / browser print), and can be labelled as a whole
+ * image. (This is a new primitive, not a Recharts chart being swapped —
+ * the "Recharts stays" rule protects the existing trend charts.)
+ *
+ * NON-DIAGNOSTIC: this component draws the raw data and nothing else. It
+ * places no beat/interval annotation on the trace, no P/QRS/T markers, no
+ * grid-derived measurement — the classic 25 mm/s · 10 mm/mV grid here is
+ * DECORATIVE calibration chrome for the fit-to-width overview, not a
+ * measurement axis. The accessible label reports the device's own result
+ * verbatim; it never asserts a HealthLog verdict.
+ *
+ * Theme-aware via semantic tokens (the tokenised `--brand-pink` grid and
+ * `--foreground` trace resolve per light/dark), and `motion-reduce`-safe
+ * by construction (no draw-on animation — the path is static).
+ */
+
+// Fixed display viewBox. The overview compresses the whole strip to this
+// width, so the grid is decorative chrome at a fixed box size rather than a
+// time-calibrated axis; the trace maps evenly across the full width.
+const VIEW_W = 1000;
+const VIEW_H = 320;
+// Small ECG box (1 mm) and bold box (5 mm) in viewBox units.
+const SMALL_BOX = 8;
+const BIG_BOX = SMALL_BOX * 5;
+// Vertical inset so the tallest R-wave never clips the top/bottom edge.
+const Y_PAD = VIEW_H * 0.12;
+
+export interface EcgWaveformProps {
+  /**
+   * Micro-volt samples. The x-position of each is implied by its index
+   * (evenly mapped across the strip); this is a shape overview, not a
+   * calibrated-time axis.
+   */
+  samples: number[];
+  /** ISO recording timestamp — read into the accessible label. */
+  recordedAt: string;
+  /** Strip duration in seconds (null when the source omitted the rate). */
+  durationSeconds: number | null;
+  /** Source-reported average heart rate (BPM), when present. */
+  averageHeartRate: number | null;
+  /**
+   * The recording DEVICE's own result, already localised and attributed to
+   * the device by the caller (e.g. "Atrial fibrillation detected"). Folded
+   * into the accessible label so a screen-reader user hears the device's
+   * verdict, never a HealthLog one. Null when the source reported none.
+   */
+  resultLabel: string | null;
+  className?: string;
+}
+
+/** Build the polyline `d`-string, mapping samples evenly across the width. */
+function buildPath(samples: number[]): string {
+  const n = samples.length;
+  if (n === 0) return "";
+
+  let min = samples[0];
+  let max = samples[0];
+  for (let i = 1; i < n; i++) {
+    if (samples[i] < min) min = samples[i];
+    if (samples[i] > max) max = samples[i];
+  }
+  const span = max - min || 1; // flat trace → centre it
+  const usableH = VIEW_H - 2 * Y_PAD;
+  const xStep = n > 1 ? VIEW_W / (n - 1) : 0;
+
+  let d = "";
+  for (let i = 0; i < n; i++) {
+    const x = i * xStep;
+    // Higher voltage → smaller y (up).
+    const y = Y_PAD + ((max - samples[i]) / span) * usableH;
+    d += `${i === 0 ? "M" : "L"}${x.toFixed(2)} ${y.toFixed(2)}`;
+    if (i < n - 1) d += " ";
+  }
+  return d;
+}
+
+export function EcgWaveform({
+  samples,
+  recordedAt,
+  durationSeconds,
+  averageHeartRate,
+  resultLabel,
+  className,
+}: EcgWaveformProps) {
+  const { t } = useTranslations();
+  const fmt = useFormatters();
+  const uid = useId();
+  const smallGridId = `ecg-grid-sm-${uid}`;
+  const bigGridId = `ecg-grid-lg-${uid}`;
+
+  const d = useMemo(() => buildPath(samples), [samples]);
+
+  // Accessible whole-image label: when + how long + average HR + the
+  // DEVICE's result. Non-normal or normal, it is the device's verdict.
+  const ariaLabel = t("insights.ecg.waveform.ariaLabel", {
+    date: fmt.dateTime(new Date(recordedAt)),
+    duration:
+      durationSeconds != null
+        ? t("insights.ecg.meta.durationValue", {
+            seconds: Math.round(durationSeconds),
+          })
+        : t("insights.ecg.meta.unknown"),
+    heartRate:
+      averageHeartRate != null
+        ? t("insights.ecg.meta.bpmValue", { bpm: averageHeartRate })
+        : t("insights.ecg.meta.unknown"),
+    result: resultLabel ?? t("insights.ecg.result.none"),
+  });
+
+  return (
+    <figure
+      data-slot="ecg-waveform"
+      role="img"
+      aria-label={ariaLabel}
+      className={cn(
+        "bg-card border-border overflow-hidden rounded-lg border",
+        className,
+      )}
+    >
+      <svg
+        viewBox={`0 0 ${VIEW_W} ${VIEW_H}`}
+        className="h-auto w-full"
+        preserveAspectRatio="xMidYMid meet"
+        aria-hidden="true"
+      >
+        <defs>
+          {/* Small 1 mm boxes. */}
+          <pattern
+            id={smallGridId}
+            width={SMALL_BOX}
+            height={SMALL_BOX}
+            patternUnits="userSpaceOnUse"
+          >
+            <path
+              d={`M ${SMALL_BOX} 0 L 0 0 0 ${SMALL_BOX}`}
+              fill="none"
+              className="stroke-brand-pink/20"
+              strokeWidth={0.5}
+            />
+          </pattern>
+          {/* Bold 5 mm boxes. */}
+          <pattern
+            id={bigGridId}
+            width={BIG_BOX}
+            height={BIG_BOX}
+            patternUnits="userSpaceOnUse"
+          >
+            <path
+              d={`M ${BIG_BOX} 0 L 0 0 0 ${BIG_BOX}`}
+              fill="none"
+              className="stroke-brand-pink/40"
+              strokeWidth={1}
+            />
+          </pattern>
+        </defs>
+        <rect width={VIEW_W} height={VIEW_H} fill={`url(#${smallGridId})`} />
+        <rect width={VIEW_W} height={VIEW_H} fill={`url(#${bigGridId})`} />
+        {d && (
+          <path
+            data-slot="ecg-trace"
+            d={d}
+            fill="none"
+            className="stroke-foreground"
+            strokeWidth={1.5}
+            strokeLinejoin="round"
+            strokeLinecap="round"
+            vectorEffect="non-scaling-stroke"
+          />
+        )}
+      </svg>
+    </figure>
+  );
+}
diff --git a/src/components/insights/insights-edit-mode.tsx b/src/components/insights/insights-edit-mode.tsx
index 0f6bff60d..fd323f27d 100644
--- a/src/components/insights/insights-edit-mode.tsx
+++ b/src/components/insights/insights-edit-mode.tsx
@@ -66,6 +66,7 @@ const SECTION_TITLE_KEYS: Record<InsightsSectionId, string> = {
   "health-status": "insights.healthStatus.sectionTitle",
   breathing: "insights.breathingScreening.sectionTitle",
   "labs-changes": "insights.labsChanges.sectionTitle",
+  ecg: "insights.ecg.sectionTitle",
 };
 
 interface InsightsEditModeProps {
diff --git a/src/lib/__tests__/insights-layout.test.ts b/src/lib/__tests__/insights-layout.test.ts
index 04dff7b0a..61bce8989 100644
--- a/src/lib/__tests__/insights-layout.test.ts
+++ b/src/lib/__tests__/insights-layout.test.ts
@@ -33,6 +33,7 @@ describe("insights-layout v2 — section id universe", () => {
       "health-status",
       "breathing",
       "labs-changes",
+      "ecg",
     ]);
   });
 
diff --git a/src/lib/insights-layout.ts b/src/lib/insights-layout.ts
index 1f7960440..538830917 100644
--- a/src/lib/insights-layout.ts
+++ b/src/lib/insights-layout.ts
@@ -116,6 +116,11 @@ export const INSIGHTS_SECTION_IDS = [
   "health-status",
   "breathing",
   "labs-changes",
+  // v1.28.50 — ECG recording surface (waveform-backed, single-lead device).
+  // Kept separate from the waveform-less `rhythm-events` timeline. Auto-merges
+  // default-invisible onto existing saved layouts (per the section resolver),
+  // default-visible for new users; data-availability-gated on top.
+  "ecg",
 ] as const;
 
 export type InsightsSectionId = (typeof INSIGHTS_SECTION_IDS)[number];
diff --git a/src/lib/insights/__tests__/ecg-decimate.test.ts b/src/lib/insights/__tests__/ecg-decimate.test.ts
new file mode 100644
index 000000000..9f2212990
--- /dev/null
+++ b/src/lib/insights/__tests__/ecg-decimate.test.ts
@@ -0,0 +1,76 @@
+import { describe, expect, it } from "vitest";
+
+import { ECG_DISPLAY_TARGET_POINTS, decimateMinMax } from "../ecg-decimate";
+
+/**
+ * v1.28.50 — ECG min/max decimation.
+ *
+ * The load-bearing property: reducing ~9000 samples to ~2500 display points
+ * must PRESERVE the R-wave peaks (the global min and max of every bucket
+ * survive), unlike a naive stride-decimation which would drop the spikes
+ * that sit between kept indices and misrepresent the trace.
+ */
+
+describe("decimateMinMax", () => {
+  it("returns the input unchanged when already at or below the target", () => {
+    const samples = [1, 2, 3, 4, 5];
+    expect(decimateMinMax(samples, 10)).toEqual(samples);
+    expect(decimateMinMax(samples, 5)).toEqual(samples);
+    // A copy, not the same reference (callers must not mutate the source).
+    expect(decimateMinMax(samples, 10)).not.toBe(samples);
+  });
+
+  it("returns an empty array for empty input", () => {
+    expect(decimateMinMax([], 2500)).toEqual([]);
+  });
+
+  it("returns the raw array for a non-positive target", () => {
+    expect(decimateMinMax([1, 2, 3, 4], 0)).toEqual([1, 2, 3, 4]);
+    expect(decimateMinMax([1, 2, 3, 4], -5)).toEqual([1, 2, 3, 4]);
+  });
+
+  it("reduces a large array to roughly the point budget", () => {
+    const n = 9000;
+    const samples = Array.from({ length: n }, (_, i) => Math.sin(i / 10));
+    const out = decimateMinMax(samples, ECG_DISPLAY_TARGET_POINTS);
+    expect(out.length).toBeLessThanOrEqual(ECG_DISPLAY_TARGET_POINTS);
+    // Two points per bucket ⇒ within a small factor of the budget.
+    expect(out.length).toBeGreaterThan(ECG_DISPLAY_TARGET_POINTS / 2);
+    expect(out.length).toBeLessThan(n);
+  });
+
+  it("preserves the global maximum (R-wave peak) hidden between strides", () => {
+    // A flat baseline with a single tall spike that a stride-decimation at
+    // this ratio would step right over.
+    const n = 6000;
+    const samples = new Array<number>(n).fill(0);
+    const spikeIdx = 1234;
+    samples[spikeIdx] = 5000; // the R-wave
+    const trough = 3777;
+    samples[trough] = -3200;
+
+    const out = decimateMinMax(samples, 1000);
+    expect(Math.max(...out)).toBe(5000);
+    expect(Math.min(...out)).toBe(-3200);
+  });
+
+  it("keeps the global peak even at a heavy reduction ratio", () => {
+    const n = 9000;
+    const samples = Array.from({ length: n }, (_, i) =>
+      Math.round(Math.sin(i / 7) * 100),
+    );
+    samples[4500] = 999999; // single dominant peak
+    const out = decimateMinMax(samples, 500);
+    expect(Math.max(...out)).toBe(999999);
+  });
+
+  it("emits bucket extremes in index order so the trace shape is preserved", () => {
+    // Rising-then-falling within the first bucket ⇒ min before max is wrong;
+    // here index 0 is the min and index 2 the max, so min must come first.
+    const samples = [0, 3, 9, 2, 8, 1, 7, 4];
+    const out = decimateMinMax(samples, 4); // 2 buckets
+    // First bucket [0..4): min=0 (idx0), max=9 (idx2) ⇒ 0 then 9.
+    expect(out[0]).toBe(0);
+    expect(out[1]).toBe(9);
+  });
+});
diff --git a/src/lib/insights/ecg-decimate.ts b/src/lib/insights/ecg-decimate.ts
new file mode 100644
index 000000000..b4a7953f7
--- /dev/null
+++ b/src/lib/insights/ecg-decimate.ts
@@ -0,0 +1,83 @@
+/**
+ * v1.28.50 — min/max decimation for the ECG display waveform.
+ *
+ * A Withings ScanWatch strip is ~9000 micro-volt samples (30 s at 300 Hz).
+ * A fit-to-width overview does not need every raw sample to reach the
+ * client, but a NAIVE stride-decimation (keep every Nth sample) silently
+ * drops the R-wave peaks that sit between the kept indices and would
+ * misrepresent the trace — the one thing an ECG must never do.
+ *
+ * Min/max decimation avoids that: the sample range is split into buckets,
+ * and each bucket emits BOTH its minimum and its maximum sample, in the
+ * order the two extremes actually occur within the bucket. The global
+ * extreme of every bucket therefore always survives, so the tall, narrow
+ * QRS spikes are preserved even at a heavy reduction ratio. The output is
+ * ~`targetPoints` values (2 per bucket); the x-position of each point is
+ * implied by its index, so the renderer maps it evenly across the strip
+ * width — the display is an overview, not a calibrated-time axis (the
+ * `?full=1` raw path serves the true-calibration view).
+ *
+ * Pure + side-effect-free so the reduction ratio and peak-preservation are
+ * unit-testable without a route.
+ */
+
+/**
+ * Default output-point budget for the decimated overview waveform
+ * (~2 points per bucket, so ~1250 buckets). Chosen per the ECG display
+ * design: dense enough that the compressed strip reads as a continuous
+ * trace, small enough that the JSON payload stays ~15–25 KB.
+ */
+export const ECG_DISPLAY_TARGET_POINTS = 2500;
+
+/**
+ * Reduce a raw sample array to at most ~`targetPoints` values using
+ * min/max decimation. Returns a copy of the input unchanged when it is
+ * already at or below the target (or the target is non-positive) — the
+ * caller then reports `decimated: false`.
+ */
+export function decimateMinMax(
+  samples: number[],
+  targetPoints: number,
+): number[] {
+  const n = samples.length;
+  if (n === 0) return [];
+  // Nothing to gain from bucketing — hand back the raw trace.
+  if (targetPoints <= 0 || targetPoints >= n) return samples.slice();
+
+  // Two output points per bucket (a min and a max), so the bucket count is
+  // half the point budget. Guard the degenerate case where bucketing would
+  // not actually shrink the array.
+  const buckets = Math.max(1, Math.floor(targetPoints / 2));
+  if (buckets * 2 >= n) return samples.slice();
+
+  const out: number[] = [];
+  const bucketSize = n / buckets;
+
+  for (let b = 0; b < buckets; b++) {
+    const start = Math.floor(b * bucketSize);
+    // The last bucket always runs to the end so no tail sample is dropped.
+    const end = b === buckets - 1 ? n : Math.floor((b + 1) * bucketSize);
+
+    let minIdx = start;
+    let maxIdx = start;
+    for (let i = start + 1; i < end; i++) {
+      if (samples[i] < samples[minIdx]) minIdx = i;
+      if (samples[i] > samples[maxIdx]) maxIdx = i;
+    }
+
+    // Emit the two extremes in the order they occur so the trace keeps its
+    // shape (an up-then-down bucket reads up-then-down). A flat bucket
+    // where min === max emits a single point.
+    if (minIdx === maxIdx) {
+      out.push(samples[minIdx]);
+    } else if (minIdx < maxIdx) {
+      out.push(samples[minIdx]);
+      out.push(samples[maxIdx]);
+    } else {
+      out.push(samples[maxIdx]);
+      out.push(samples[minIdx]);
+    }
+  }
+
+  return out;
+}
diff --git a/src/lib/openapi/routes/insights/paths.ts b/src/lib/openapi/routes/insights/paths.ts
index b25d3e044..097c14092 100644
--- a/src/lib/openapi/routes/insights/paths.ts
+++ b/src/lib/openapi/routes/insights/paths.ts
@@ -4,9 +4,11 @@
  * Schema declarations live in `./schemas`; this module is the path orchestrator.
  */
 import type { ZodOpenApiObject } from "zod-openapi";
+import { z } from "zod/v4";
 import {
   consentRequiredResponse,
   dataEnvelope,
+  errorEnvelope,
   moduleDisabledResponse,
   stdResponses,
 } from "../shared";
@@ -31,6 +33,9 @@ import {
   insightsPregenerateRequest,
   insightsPregenerateResponse,
   dashboardSnapshotResponse,
+  ecgListResponse,
+  ecgDetailQuery,
+  ecgDetailResponse,
 } from "./schemas";
 
 export const insightsPaths: NonNullable<ZodOpenApiObject["paths"]> = {
@@ -429,6 +434,61 @@ export const insightsPaths: NonNullable<ZodOpenApiObject["paths"]> = {
       },
     },
   },
+  "/api/insights/ecg": {
+    get: {
+      tags: ["Insights"],
+      summary: "ECG recording list (metadata only)",
+      description:
+        "v1.28.50 — the authenticated user's ECG recordings as a cheap, index-covered metadata list (recorded time, duration, sampling rate, sample count, average heart rate, lead, and the DEVICE's own rhythm classification). NEVER decrypts or returns the waveform — the per-recording strip is fetched on demand from GET /api/insights/ecg/{id}. Reflects only the recording device's certified on-device classification, verbatim; HealthLog never re-classifies an ECG or produces a diagnosis. Data-availability-gated: an empty account returns `hasRecordings: false`. Module-gated on `insights` and the operator `insightStatus` assistant surface; no LLM call. Auth via cookie or Bearer.",
+      responses: {
+        "200": {
+          description: "The ECG recording list (possibly empty).",
+          content: {
+            "application/json": {
+              schema: dataEnvelope(ecgListResponse, "EcgListResponseEnvelope"),
+            },
+          },
+        },
+        ...moduleDisabledResponse,
+        ...stdResponses,
+      },
+    },
+  },
+  "/api/insights/ecg/{id}": {
+    get: {
+      tags: ["Insights"],
+      summary: "One ECG recording with waveform",
+      description:
+        "v1.28.50 — one recording's decrypted waveform plus metadata and the DEVICE's verbatim classification. Ownership is narrowed in the query where (`{ id, userId }`) so a cross-user read is structurally impossible; a foreign or unknown id 404s (existence sealed). The waveform is AES-256-GCM at rest, decrypted through the fail-closed codec. By default the ~9000-sample strip is min/max-decimated to ~2500 display points so R-wave peaks survive; `?full=1` returns the raw array. HealthLog does not interpret the trace, measure intervals, annotate beats, or emit a verdict of its own. Module-gated on `insights` and the operator `insightStatus` assistant surface; no LLM call. `no-store`. Auth via cookie or Bearer.",
+      requestParams: {
+        path: z.object({
+          id: z.string().describe("The ECG recording id (cuid)."),
+        }),
+        query: ecgDetailQuery,
+      },
+      responses: {
+        "200": {
+          description:
+            "The recording's waveform + metadata + device classification.",
+          content: {
+            "application/json": {
+              schema: dataEnvelope(
+                ecgDetailResponse,
+                "EcgDetailResponseEnvelope",
+              ),
+            },
+          },
+        },
+        "404": {
+          description:
+            "No ECG recording with that id for the authenticated user (existence sealed — a foreign id is indistinguishable from a missing one).",
+          content: { "application/json": { schema: errorEnvelope } },
+        },
+        ...moduleDisabledResponse,
+        ...stdResponses,
+      },
+    },
+  },
   "/api/insights/correlations": {
     get: {
       tags: ["Insights"],
diff --git a/src/lib/openapi/routes/insights/schemas.ts b/src/lib/openapi/routes/insights/schemas.ts
index 8451451ad..98b90427f 100644
--- a/src/lib/openapi/routes/insights/schemas.ts
+++ b/src/lib/openapi/routes/insights/schemas.ts
@@ -1003,3 +1003,135 @@ const insightCard = z
 export const insightsCardsResponse = z
   .array(insightCard)
   .meta({ id: "InsightsCardsResponse" });
+
+// v1.28.50 — ECG recording surface. The device's own AFib verdict, verbatim.
+// Only three RhythmClassification values occur for an ECG strip; the field is
+// nullable when the source omitted a classification.
+const ecgClassification = z
+  .enum(["IRREGULAR", "NOT_DETECTED", "INCONCLUSIVE"])
+  .nullable()
+  .describe(
+    "The RECORDING DEVICE's own rhythm classification, surfaced verbatim: IRREGULAR (device flagged possible atrial fibrillation), NOT_DETECTED (algorithm ran, nothing flagged), INCONCLUSIVE (poor signal / out-of-range HR). Null when the source reported none. HealthLog never re-classifies an ECG — this is the device's certified on-device result, not a HealthLog verdict.",
+  );
+
+const ecgRecordingListItem = z
+  .object({
+    id: z.string().describe("Recording id (cuid)."),
+    recordedAt: z.iso
+      .datetime({ offset: true })
+      .describe("On-device recording time (the display timestamp)."),
+    durationSeconds: z
+      .number()
+      .nullable()
+      .describe(
+        "`sampleCount / samplingFrequency` in seconds; null when the source omitted the sampling frequency.",
+      ),
+    samplingFrequency: z
+      .number()
+      .int()
+      .describe(
+        "Signal sampling rate in Hz (Withings ScanWatch = 300); 0 when the source omitted it.",
+      ),
+    sampleCount: z
+      .number()
+      .int()
+      .describe("Number of samples in the (encrypted) waveform array."),
+    averageHeartRate: z
+      .number()
+      .int()
+      .nullable()
+      .describe(
+        "Source-reported average heart rate (BPM) for the strip, when present.",
+      ),
+    lead: z
+      .string()
+      .nullable()
+      .describe(
+        "Recording lead label when the source reports it; null for the single-lead ScanWatch (Lead I).",
+      ),
+    classification: ecgClassification,
+    source: z
+      .string()
+      .describe("Measurement source that wrote the recording (e.g. WITHINGS)."),
+    hasWaveform: z
+      .boolean()
+      .describe(
+        "True when a waveform is stored (`sampleCount > 0`); false for a verdict-only fallback event with no signal to fetch.",
+      ),
+  })
+  .meta({ id: "EcgRecordingListItem" });
+
+export const ecgListResponse = z
+  .object({
+    recordings: z
+      .array(ecgRecordingListItem)
+      .describe("The user's ECG recordings, newest first (capped at 200)."),
+    hasRecordings: z
+      .boolean()
+      .describe(
+        "False for an account with no recordings — the client un-mounts the whole ECG surface (data-availability floor).",
+      ),
+  })
+  .meta({
+    id: "EcgListResponse",
+    description:
+      "Metadata-only ECG recording list. Never carries the waveform — the per-recording strip is fetched on demand from GET /api/insights/ecg/{id}. Read-only; no LLM call. Reflects only the device's own classification, never a HealthLog interpretation.",
+  });
+
+export const ecgDetailQuery = z
+  .object({
+    full: z
+      .literal("1")
+      .optional()
+      .describe(
+        "`1` returns the RAW, un-decimated sample array (the true-calibration 25 mm/s · 10 mm/mV zoom view). Omitted returns the min/max-decimated ~2500-point fit-to-width overview (`decimated: true`).",
+      ),
+  })
+  .meta({ id: "EcgDetailQuery" });
+
+export const ecgDetailResponse = z
+  .object({
+    recordedAt: z.iso
+      .datetime({ offset: true })
+      .describe("On-device recording time (the display timestamp)."),
+    durationSeconds: z
+      .number()
+      .nullable()
+      .describe(
+        "Strip duration in seconds; null when the sampling frequency was 0.",
+      ),
+    samplingFrequency: z
+      .number()
+      .int()
+      .describe("Signal sampling rate in Hz (300 for a ScanWatch)."),
+    averageHeartRate: z
+      .number()
+      .int()
+      .nullable()
+      .describe(
+        "Source-reported average heart rate (BPM) for the strip, when present.",
+      ),
+    lead: z
+      .string()
+      .nullable()
+      .describe(
+        "Recording lead label when reported; null for the single-lead ScanWatch (Lead I).",
+      ),
+    classification: ecgClassification,
+    source: z.string().describe("Measurement source that wrote the recording."),
+    samples: z
+      .array(z.number())
+      .describe(
+        "Micro-volt waveform samples. Min/max-decimated to ~2500 points by default so R-wave peaks survive the fit-to-width compression; the raw array when `?full=1`. The x-position of each sample is implied by its index (an overview trace, not a calibrated-time axis) unless `decimated` is false.",
+      ),
+    decimated: z
+      .boolean()
+      .describe(
+        "True when `samples` was min/max-decimated for display; false when the raw array is returned (`?full=1`, or a strip already at or below the display budget).",
+      ),
+  })
+  .meta({
+    id: "EcgDetailResponse",
+    description:
+      "One ECG recording's decrypted waveform plus metadata and the DEVICE's verbatim classification. Ownership is narrowed in the query where — a foreign / unknown id 404s. The waveform is AES-256-GCM at rest, decrypted through the fail-closed codec. HealthLog does not interpret the trace, measure intervals, annotate beats, or emit a verdict of its own. no-store.",
+  });
diff --git a/src/lib/query-keys/insights.ts b/src/lib/query-keys/insights.ts
index 7d5a517fb..d2d015f3a 100644
--- a/src/lib/query-keys/insights.ts
+++ b/src/lib/query-keys/insights.ts
@@ -71,6 +71,19 @@ export const insightsKeys = {
    * row busts it via the prefix).
    */
   insightsRhythmEvents: () => ["insights", "rhythm-events"] as const,
+  /**
+   * v1.28.50 — ECG recording surface. The metadata list
+   * (`/api/insights/ecg`) and the per-recording waveform detail
+   * (`/api/insights/ecg/[id]`). The detail key carries the recording id
+   * plus a `full` discriminant so the fit-to-width overview waveform and
+   * the raw `?full=1` true-calibration array cache independently and never
+   * poison each other (same key + different sample density would). Both
+   * sit under the `["insights"]` prefix so a sync that lands a new
+   * recording busts them via the standard insights invalidation fan-out.
+   */
+  insightsEcgList: () => ["insights", "ecg"] as const,
+  insightsEcgDetail: (id: string, full: boolean) =>
+    ["insights", "ecg", id, full ? "full" : "overview"] as const,
   /**
    * v1.10.0 — derived-wellness metrics. One generic route
    * (`/api/insights/derived?metric=…[&type=…]`) backs the vitals