Let a dealer take the table off the device it's stuck on

The night lives in one browser's localStorage and nowhere else. A dealer whose phone
dies, or who wants to carry on from the tablet after the break, loses the stacks, the
buy-ins, where the button is and the whole hand log. The CSV export can't bring any of
it back: it records what happened, not where the table stands.

The table can now be written to a file and read back. Round-tripped through the real
UI, a hand in progress comes back mid-hand — blinds posted, the same seat on the
clock, the button where it was.

Loading replaces everything, so it asks first and names both sides rather than saying
"are you sure": how many players are in the file and when it was saved, against how
many players and how many logged hands are about to go. It goes through the same
undoable path as the header buttons, so the toast offers the way back, and the
confirm says so instead of overstating it.

Reading a file goes through exactly the same migration a save from storage does —
load() had that logic inline and it is now a function both call. A second, looser path
for imports is how a format grows two meanings of the same field.

What it refuses, each with something a dealer can act on and never a half-loaded
table: anything that isn't JSON, JSON with no seats in it, a save from some other tool
that happens to carry a `kind`, and a file from a newer version — that last one
because loading it risks reading a field whose meaning has changed, and the dealer
would find out from the money. What it accepts anyway: a bare table with no envelope,
for somebody who copied the storage value out by hand.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_015bnp7xKUPFFSpwkYNFaPgb

JoshHeaps.Net/Pages/Casino/TexasHoldem.cshtml

@@ -155,6 +155,17 @@
                         <button id="exportHistoryBtn" class="holdemBtn holdemBtnSmall">Export CSV</button>
                         <button id="clearHistoryBtn" class="holdemBtn holdemBtnSmall holdemBtnDanger">Clear history</button>
                     </div>
+
+                    <h3 class="panelSubhead">The table itself</h3>
+                    <p class="fieldHint">
+                        The night lives in this browser and nowhere else. Save it to a file to carry it
+                        to another device, or to have something to come back to if this one dies.
+                    </p>
+                    <div class="handHistoryActions">
+                        <button id="saveTableBtn" class="holdemBtn holdemBtnSmall">Save table file</button>
+                        <button id="loadTableBtn" class="holdemBtn holdemBtnSmall">Load table file</button>
+                        <input id="loadTableInput" type="file" accept="application/json,.json" hidden />
+                    </div>
                 </div>
             </details>
 

JoshHeaps.Net/wwwroot/js/casino/holdem/main.js

@@ -598,6 +598,72 @@ document.addEventListener("DOMContentLoaded", () => {
         Toast.show("Hand history cleared.", { duration: 2500 });
     });
 
+    document.getElementById("saveTableBtn").addEventListener("click", () => {
+        const blob = new Blob([HoldemState.toBackup(state)], { type: "application/json" });
+        const url = URL.createObjectURL(blob);
+        const link = document.createElement("a");
+        link.href = url;
+        link.download = HoldemState.backupFileName();
+        document.body.appendChild(link);
+        link.click();
+        document.body.removeChild(link);
+        URL.revokeObjectURL(url);
+        Toast.show(`Table saved as ${link.download}.`, { duration: 3500 });
+    });
+
+    document.getElementById("loadTableBtn").addEventListener("click", () => {
+        document.getElementById("loadTableInput").click();
+    });
+
+    document.getElementById("loadTableInput").addEventListener("change", async e => {
+        const file = e.target.files && e.target.files[0];
+        // Cleared straight away so picking the same file twice still fires a change.
+        e.target.value = "";
+        if (!file) return;
+
+        let text;
+        try {
+            text = await file.text();
+        } catch {
+            Toast.show("That file couldn't be read.", { duration: 4000 });
+            return;
+        }
+
+        const result = HoldemState.fromBackup(text);
+        if (result.error) {
+            Toast.show(result.error, { duration: 5000 });
+            return;
+        }
+
+        // Loading replaces everything: stacks, buy-ins, the button, the log. Naming
+        // what is about to be lost is the difference between a dealer choosing that
+        // and discovering it — and the current table might be the live one.
+        const here = HoldemState.sessionStandings(state).length;
+        const incoming = HoldemState.sessionStandings(result.table).length;
+        const when = result.savedAt ? new Date(result.savedAt) : null;
+        const saidWhen = when && !Number.isNaN(when.getTime())
+            ? ` It was saved ${when.toLocaleString()}.`
+            : "";
+        const ok = await Dialog.confirm({
+            title: "Replace this table?",
+            message:
+                `The file has a table with ${incoming} ${incoming === 1 ? "player" : "players"} in it.${saidWhen} ` +
+                `Loading it replaces the table on screen — ${here} ${here === 1 ? "player" : "players"}, ` +
+                `${(state.handHistory || []).length} logged ${(state.handHistory || []).length === 1 ? "hand" : "hands"}. ` +
+                `Undo will bring it back for a few seconds; after that it is gone.`,
+            confirmLabel: "Load it",
+            danger: true,
+        });
+        if (!ok) return;
+
+        runUndoable("loading a saved table", () => {
+            // Replace the contents rather than the reference: everything on the page
+            // holds a pointer to this object.
+            Object.keys(state).forEach(key => { delete state[key]; });
+            Object.assign(state, result.table);
+        });
+    });
+
     // The filter is how the dealer looks at the log, not something about the table, so
     // it lives on the view: it isn't saved, isn't undoable, and doesn't reach the other
     // tab. Clearing the history clears it too, since there is nothing left to filter.

JoshHeaps.Net/wwwroot/js/casino/holdem/state.js

@@ -164,13 +164,18 @@ const HoldemState = {
         return this.createDefault();
     },
 
-    load() {
+    // Everything a table has to be put through before it can be trusted, whichever
-        let raw = null;
+    // direction it arrived from.
-        try {
+    //
-            raw = localStorage.getItem(this.STORAGE_KEY);
+    // Pulled out of load() so a table read from a file goes through exactly the same
-            if (!raw) return this.createDefault();
+    // checks as one read from storage. A second, looser path for imports is how a
-            const parsed = JSON.parse(raw);
+    // format grows two meanings of the same field.
-            if (!parsed || !Array.isArray(parsed.seats)) return this.failedLoad(raw);
+    //
+    // Returns null for anything that isn't a table at all; every other repair is
+    // silent and forward, the way a save from an older version is treated.
+    migrate(parsed) {
+        if (!parsed || !Array.isArray(parsed.seats)) return null;
+        {
             if (typeof parsed.handNumber !== "number" || parsed.handNumber < 1) parsed.handNumber = 1;
             if (!Array.isArray(parsed.handHistory)) parsed.handHistory = [];
             if (typeof parsed.discarded !== "number" || !(parsed.discarded >= 0)) parsed.discarded = 0;
@@ -215,12 +220,85 @@ const HoldemState = {
             });
 
             return parsed;
+        }
+    },
+
+    load() {
+        let raw = null;
+        try {
+            raw = localStorage.getItem(this.STORAGE_KEY);
+            if (!raw) return this.createDefault();
+            const migrated = this.migrate(JSON.parse(raw));
+            if (!migrated) return this.failedLoad(raw);
+            return migrated;
         } catch {
             // Malformed JSON — a truncated write, another tab, a browser hiccup.
             return this.failedLoad(raw);
         }
     },
 
+    // ---- Taking the table off this device ------------------------------------
+    //
+    // A night lives in one browser's localStorage and nowhere else. A dealer whose
+    // phone dies, or who wants to carry on from the tablet after the break, loses the
+    // stacks, the buy-ins, where the button is and the whole hand log — and the CSV
+    // export can't bring any of that back, because it records what happened rather
+    // than where the table stands.
+    //
+    // So the table can be written out as a file and read back in. Same shape that goes
+    // into storage, wrapped in enough to recognise it later.
+    BACKUP_KIND: "casino.holdem.table",
+    BACKUP_VERSION: 1,
+
+    toBackup(state) {
+        return JSON.stringify({
+            kind: this.BACKUP_KIND,
+            version: this.BACKUP_VERSION,
+            savedAt: new Date().toISOString(),
+            table: state,
+        }, null, 2);
+    },
+
+    // Reads a file back. Returns { table } on success, or { error } with something a
+    // dealer can act on — never a half-loaded table, because the failure mode there is
+    // a night that looks restored and isn't.
+    fromBackup(text) {
+        let parsed;
+        try {
+            parsed = JSON.parse(text);
+        } catch {
+            return { error: "That file isn't a saved table — it couldn't be read as JSON." };
+        }
+        if (!parsed || typeof parsed !== "object") {
+            return { error: "That file isn't a saved table." };
+        }
+        // A bare table, from someone who copied the storage value out by hand, is
+        // still a table. The envelope is a convenience, not a password.
+        const table = parsed.kind === this.BACKUP_KIND || parsed.table ? parsed.table : parsed;
+        if (parsed.kind && parsed.kind !== this.BACKUP_KIND) {
+            return { error: "That file is a save from something else, not a Hold'em table." };
+        }
+        const migrated = this.migrate(table);
+        if (!migrated) {
+            return { error: "That file doesn't have a table in it — no seats were found." };
+        }
+        if (parsed.version > this.BACKUP_VERSION) {
+            // Newer than this build understands. Loading it anyway risks reading a
+            // field that has changed meaning, and the dealer would find out from the
+            // money, so say so instead.
+            return { error: "That table was saved by a newer version of this tool. Update, then load it." };
+        }
+        return { table: migrated, savedAt: parsed.savedAt || null };
+    },
+
+    // What the file is called. Dated, because a dealer who saves twice in a night
+    // should not have to guess which is which.
+    backupFileName(now = new Date()) {
+        const pad = n => String(n).padStart(2, "0");
+        return `holdem-table-${now.getFullYear()}-${pad(now.getMonth() + 1)}-${pad(now.getDate())}` +
+            `-${pad(now.getHours())}${pad(now.getMinutes())}.json`;
+    },
+
     // True once a save has failed. The UI reads this to keep saying so, because a
     // toast is a moment and this is a fact about the rest of the night.
     saveFailed: false,

tests/holdem/tableFile.test.js

@@ -0,0 +1,155 @@
+// Taking the table off this device.
+//
+// A night lives in one browser's localStorage and nowhere else. A dealer whose phone
+// dies, or who wants to carry on from the tablet after the break, loses the stacks,
+// the buy-ins, where the button is and the whole hand log — and the CSV export can't
+// bring any of that back, because it records what happened rather than where the
+// table stands.
+const test = require("node:test");
+const { describe } = require("node:test");
+const assert = require("node:assert");
+const { HoldemState, Betting, makeTable } = require("./load");
+
+const aNight = () => {
+    const state = makeTable({ seatCount: 9, seated: [0, 1, 2, 3], stack: 200, dealerSeatIndex: 1 });
+    ["Ann", "Ben", "Cal", "Dee"].forEach((name, i) => {
+        state.seats[i].name = name;
+        state.seats[i].buyIns = 200;
+    });
+    state.seats[2].stack = 340;
+    state.notes = "Cal owes the bar $12";
+    Betting.beginHand(state);
+    HoldemState.recordHand(state, [{ id: state.seats[2].id, label: "Cal", amount: 60 }]);
+    return state;
+};
+
+describe("a table written out and read back", () => {
+    test("comes back the same table", () => {
+        const before = aNight();
+        const after = HoldemState.fromBackup(HoldemState.toBackup(before)).table;
+
+        assert.deepEqual(after.seats.map(p => p.name), before.seats.map(p => p.name));
+        assert.deepEqual(after.seats.map(p => p.stack), before.seats.map(p => p.stack));
+        assert.deepEqual(after.seats.map(p => p.buyIns), before.seats.map(p => p.buyIns));
+        assert.equal(after.dealerSeatIndex, before.dealerSeatIndex);
+        assert.equal(after.handNumber, before.handNumber);
+        assert.equal(after.notes, before.notes);
+        assert.equal(after.handHistory.length, before.handHistory.length);
+    });
+
+    test("keeps the things a CSV can't carry", () => {
+        // The whole reason this exists: an export records what happened, not where the
+        // table stands.
+        const before = aNight();
+        const after = HoldemState.fromBackup(HoldemState.toBackup(before)).table;
+
+        assert.equal(after.bettingOpen, before.bettingOpen, "a hand in progress is still in progress");
+        assert.deepEqual(after.postedBlinds, before.postedBlinds, "so the next rotation is right");
+        assert.equal(after.street, before.street);
+        assert.deepEqual(after.seats.map(p => p.committed), before.seats.map(p => p.committed));
+        assert.deepEqual(after.chipLegend, before.chipLegend);
+    });
+
+    test("the standings and the bank check agree across the trip", () => {
+        const before = aNight();
+        const after = HoldemState.fromBackup(HoldemState.toBackup(before)).table;
+
+        assert.deepEqual(HoldemState.sessionStandings(after), HoldemState.sessionStandings(before));
+        assert.deepEqual(HoldemState.bankReconciliation(after), HoldemState.bankReconciliation(before));
+    });
+
+    test("it can be dealt from straight away", () => {
+        const before = aNight();
+        HoldemState.startNextHand(before);
+        const after = HoldemState.fromBackup(HoldemState.toBackup(before)).table;
+
+        Betting.beginHand(after);
+        assert.equal(after.bettingOpen, true);
+        assert.ok(after.actingSeatIndex !== null, "somebody is on the clock");
+    });
+});
+
+describe("what it refuses", () => {
+    const refuses = (text, because) => {
+        const result = HoldemState.fromBackup(text);
+        assert.ok(result.error, because);
+        assert.equal(result.table, undefined, "and never hands back half a table");
+    };
+
+    test("something that isn't JSON", () => {
+        refuses("not a file", "unreadable");
+        refuses("", "empty");
+    });
+
+    test("JSON that isn't a table", () => {
+        refuses('{"hello":"world"}', "no seats in it");
+        refuses("[1,2,3]", "an array of nothing");
+        refuses("null", "null");
+    });
+
+    test("a save from something else that happens to be JSON", () => {
+        refuses('{"kind":"some.other.tool","table":{"seats":[]}}', "wrong kind");
+    });
+
+    test("a file from a newer version, rather than guessing at it", () => {
+        // Loading it risks reading a field whose meaning has changed, and the dealer
+        // would find out from the money.
+        const backup = JSON.parse(HoldemState.toBackup(aNight()));
+        backup.version = HoldemState.BACKUP_VERSION + 1;
+        const result = HoldemState.fromBackup(JSON.stringify(backup));
+        assert.match(result.error, /newer version/i);
+    });
+});
+
+describe("what it accepts anyway", () => {
+    test("a bare table, with no envelope around it", () => {
+        // Somebody who copied the storage value out by hand. The envelope is a
+        // convenience, not a password.
+        const state = aNight();
+        const result = HoldemState.fromBackup(JSON.stringify(state));
+        assert.ok(!result.error);
+        assert.deepEqual(result.table.seats.map(p => p.name), state.seats.map(p => p.name));
+    });
+
+    test("a table from before fields that exist now, migrated on the way in", () => {
+        // Same repairs a save from an older version gets, because it is the same
+        // function — a second, looser path for imports is how a format grows two
+        // meanings of the same field.
+        const state = aNight();
+        const raw = JSON.parse(JSON.stringify(state));
+        delete raw.deadButton;
+        delete raw.postedBlinds;
+        delete raw.dealtLastHand;
+        delete raw.discarded;
+        raw.seats.forEach(p => { delete p.buyIns; });
+
+        const { table, error } = HoldemState.fromBackup(JSON.stringify({
+            kind: HoldemState.BACKUP_KIND, version: 1, table: raw,
+        }));
+        assert.ok(!error);
+        assert.equal(table.deadButton, false);
+        assert.deepEqual(table.dealtLastHand, []);
+        assert.equal(table.discarded, 0);
+        assert.equal(table.seats[0].buyIns, 0);
+    });
+
+    test("the time it was saved comes back with it", () => {
+        const result = HoldemState.fromBackup(HoldemState.toBackup(aNight()));
+        assert.ok(result.savedAt, "so the dealer can tell two files apart");
+        assert.ok(!Number.isNaN(new Date(result.savedAt).getTime()));
+    });
+});
+
+describe("the file itself", () => {
+    test("is named with the date and time, so two saves in a night are told apart", () => {
+        const at = new Date(2026, 8, 2, 21, 5);
+        assert.equal(HoldemState.backupFileName(at), "holdem-table-2026-09-02-2105.json");
+    });
+
+    test("says what it is, for anyone finding it in a downloads folder", () => {
+        const parsed = JSON.parse(HoldemState.toBackup(aNight()));
+        assert.equal(parsed.kind, "casino.holdem.table");
+        assert.equal(parsed.version, 1);
+        assert.ok(parsed.table.seats.length > 0);
+    });
+});