diff --git a/koha-tmpl/intranet-tmpl/prog/en/includes/str/viewlog.inc b/koha-tmpl/intranet-tmpl/prog/en/includes/str/viewlog.inc
index 53e7a124ad..b7e449f03a 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/includes/str/viewlog.inc
+++ b/koha-tmpl/intranet-tmpl/prog/en/includes/str/viewlog.inc
@@ -94,5 +94,52 @@
         CRON: _("Cron job"),
         UPGRADE: _("Upgrade"),
     };
+
+    /*
+     * Translation map for circulation override codes that appear in the
+     * `forced` and `confirmations` arrays of a CIRCULATION info column
+     * JSON payload (see C4::Circulation::CanBookBeIssued and friends).
+     */
+    var override_labels = {
+        HOLD_POLICY_OVERRIDE: _("Hold policy override"),
+        INVALID_DATE: _("Invalid date confirmed"),
+        DEBT_GUARANTEES: _("Guarantees had debts"),
+        DEBT_GUARANTORS: _("Guarantors had debts"),
+        DEBT: _("Patron had debt"),
+        USERBLOCKEDOVERDUE: _("Patron had overdues"),
+        USERBLOCKEDNOENDDATE: _("Patron had an indefinite restriction"),
+        ADDITIONAL_MATERIALS: _("Additional materials were confirmed"),
+        RENEW_ISSUE: _("Renewal"),
+        ISSUED_TO_ANOTHER: _("Item was issued to another patron prior to this checkout"),
+        PATRON_CANT: _("Max renewals reached"),
+        TOO_MANY: _("Too many checkouts"),
+        PREVISSUE: _("Patron was notified of previous issues"),
+        NOT_FOR_LOAN: _("Item was not for loan"),
+        NOT_FOR_LOAN_FORCING: _("Item was not for loan"),
+        ITEM_LOST: _("Item was reported lost"),
+        BORRNOTSAMEBRANCH: _("Patron does not belong to this library"),
+        RENTALCHARGE: _("Item had a rental charge"),
+        RECALLED: _("Item was recalled"),
+        RESERVE_WAITING: _("Hold waiting on item"),
+        RESERVED: _("Hold placed on item"),
+        TRANSFERRED: _("Item was transferred"),
+        PROCESSING: _("Item was in processing"),
+        BOOKED_EARLY: _("Item was booked and checked out early"),
+        BOOKED_TO_ANOTHER: _("Item was booked to another patron"),
+        AGE_RESTRICTION: _("Item has an age restriction"),
+        HIGHHOLDS: _("Item had high holds"),
+        BIBLIO_ALREADY_ISSUED: _("An item from this bibliographic record is already checked out"),
+        DEBARRED: _("Patron is restricted"),
+        RENEWAL_LIMIT: _("Renewal limit override"),
+        UNSEEN_LIMIT: _("Override unseen item restriction"),
+        AUTO_TOO_SOON: _("Override auto-renew too soon restriction"),
+        AUTO_TOO_LATE: _("Override auto-renew too late restriction"),
+        ACCOUNT_EXPIRED: _("Account expired override"),
+        ON_RESERVE: _("Override renew hold for another"),
+        TOO_MUCH: _("Override auto-renew too much owing restriction"),
+        CURRENTISSUE: _("Item is currently checked out to this patron"),
+        UNSEEN: _("Unseen renewal"),
+        SEEN: _("Seen renewal"),
+    };
 </script>
 <!-- / str/viewlog.inc -->
diff --git a/koha-tmpl/intranet-tmpl/prog/js/viewlog.js b/koha-tmpl/intranet-tmpl/prog/js/viewlog.js
index 7e8296b758..e7bac21dda 100644
--- a/koha-tmpl/intranet-tmpl/prog/js/viewlog.js
+++ b/koha-tmpl/intranet-tmpl/prog/js/viewlog.js
@@ -1,3 +1,194 @@
+/**
+ * Recursively collect changed entries from a Struct::Diff node.
+ * Returns an array of { key, before, after } objects.
+ * Nested diffs are flattened with dot-separated keys.
+ */
+function collectDiffEntries(node, prefix) {
+    var entries = [];
+    Object.keys(node).forEach(function (key) {
+        var change = node[key];
+        var fullKey = prefix ? prefix + "." + key : key;
+        if ("O" in change || "N" in change) {
+            entries.push({ key: fullKey, before: change.O, after: change.N });
+        } else if ("A" in change) {
+            entries.push({ key: fullKey, before: undefined, after: change.A });
+        } else if ("R" in change) {
+            entries.push({ key: fullKey, before: change.R, after: undefined });
+        } else if ("D" in change) {
+            entries = entries.concat(collectDiffEntries(change.D, fullKey));
+        }
+    });
+    return entries;
+}
+
+/**
+ * Pretty-print a parsed JSON value as nested <ul> markup. Arrays become
+ * ordered lists preserving MARC-in-JSON field order; objects render their
+ * keys. Used by both the struct-diff renderer and the catalog info renderer.
+ */
+function fmtJsonValue(v) {
+    if (v === undefined || v === null) return "";
+    if (typeof v !== "object") return $("<span>").text(String(v)).html();
+    if (Array.isArray(v)) {
+        var items = v
+            .map(function (item) {
+                return "<li>" + fmtJsonValue(item) + "</li>";
+            })
+            .join("");
+        return '<ul class="diff-obj">' + items + "</ul>";
+    }
+    var items = Object.keys(v)
+        .map(function (k) {
+            return (
+                "<li>" +
+                $("<span>").text(k).html() +
+                ": " +
+                fmtJsonValue(v[k]) +
+                "</li>"
+            );
+        })
+        .join("");
+    return '<ul class="diff-obj">' + items + "</ul>";
+}
+
+/**
+ * Render the info column for a CATALOGUING or AUTHORITIES log entry.
+ * The payload is "biblio <JSON>" or "authority <JSON>" where the JSON
+ * is the pre-change (MODIFY) or final (DELETE) state of the record,
+ * including a MARC-in-JSON `_marc` key. Returns rendered HTML, or null
+ * if the text doesn't look like a record JSON payload (e.g. the bare
+ * "biblio" / "authority" prefix logged on ADD).
+ */
+function renderRecordInfo(raw) {
+    if (!raw) return null;
+    var match = raw.match(/^(?:biblio|authority)\s+(\{[\s\S]*\})\s*$/);
+    if (!match) return null;
+    var parsed;
+    try {
+        parsed = JSON.parse(match[1]);
+    } catch (e) {
+        return null;
+    }
+    return '<div class="loginfo-struct">' + fmtJsonValue(parsed) + "</div>";
+}
+
+/* global override_labels */
+
+/**
+ * Render the info column for a CIRCULATION log entry whose payload is a
+ * JSON object containing `forced` and/or `confirmations` arrays of
+ * override codes. Returns rendered HTML, or null if the payload doesn't
+ * look like a circulation JSON object.
+ */
+function renderCircInfo(raw) {
+    if (!raw) return null;
+    var trimmed = raw.replace(/^\s+|\s+$/g, "");
+    if (trimmed.charAt(0) !== "{") return null;
+    var parsed;
+    try {
+        parsed = JSON.parse(trimmed);
+    } catch (e) {
+        return null;
+    }
+    if (!parsed || typeof parsed !== "object") return null;
+
+    var forced =
+        Array.isArray(parsed.forced) && parsed.forced.length
+            ? parsed.forced
+            : null;
+    var confirmations =
+        Array.isArray(parsed.confirmations) && parsed.confirmations.length
+            ? parsed.confirmations
+            : null;
+    if (!forced && !confirmations) return null;
+
+    function translate(code) {
+        return override_labels[code] || escapeHtml(code);
+    }
+
+    var html = "";
+    if (forced) {
+        html += forced
+            .map(function (c) {
+                return '<div class="forced">' + translate(c) + "</div>";
+            })
+            .join("");
+    }
+    if (confirmations) {
+        html += confirmations
+            .map(function (c) {
+                return '<div class="confirmed">' + translate(c) + "</div>";
+            })
+            .join("");
+    }
+    return html;
+}
+
+/**
+ * Render Struct::Diff JSON as a human-readable before/after table.
+ * Falls back to a <pre> block for non-Struct::Diff JSON or plain text.
+ */
+function renderStructDiff(raw) {
+    if (!raw) return "";
+    var diff;
+    try {
+        diff = JSON.parse(raw);
+    } catch (e) {
+        return $("<pre>").text(raw)[0].outerHTML;
+    }
+    if (!diff || !diff.D || typeof diff.D !== "object") {
+        return $("<pre>").text(raw)[0].outerHTML;
+    }
+
+    var entries = collectDiffEntries(diff.D, "");
+    if (!entries.length) return "";
+
+    var rows = entries
+        .map(function (e) {
+            var before =
+                e.before !== undefined
+                    ? "<del>" + fmtJsonValue(e.before) + "</del>"
+                    : "";
+            var after =
+                e.after !== undefined
+                    ? "<ins>" + fmtJsonValue(e.after) + "</ins>"
+                    : "";
+            return (
+                "<tr>" +
+                '<td class="diff-key">' +
+                $("<span>").text(e.key).html() +
+                "</td>" +
+                '<td class="diff-before">' +
+                before +
+                "</td>" +
+                '<td class="diff-after">' +
+                after +
+                "</td>" +
+                "</tr>"
+            );
+        })
+        .join("");
+
+    return (
+        '<table class="struct-diff">' +
+        "<thead><tr>" +
+        "<th>" +
+        __("Field") +
+        "</th>" +
+        "<th>" +
+        __("Before") +
+        "</th>" +
+        "<th>" +
+        __("After") +
+        "</th>" +
+        "</tr></thead>" +
+        "<tbody>" +
+        rows +
+        "</tbody>" +
+        "</table>"
+    );
+}
+
 function tickAll(section) {
     $("input[type='checkbox'][name='" + section + "']").prop("checked", true);
     $("#" + section.slice(0, -1) + "ALL").prop("checked", true);
@@ -202,8 +393,16 @@ function renderInfo(data, type, row) {
         );
     }
 
-    var rendered = renderRecordInfo(info);
-    var body = rendered !== null ? rendered : escapeHtml(info);
+    var body = null;
+    if (mod == "CIRCULATION") {
+        body = renderCircInfo(info);
+    }
+    if (body === null) {
+        body = renderRecordInfo(info);
+    }
+    if (body === null) {
+        body = escapeHtml(info);
+    }
     return (
         '<div class="loginfo" id="loginfo' +
         escapeHtml(action_id) +