Optional conversion and cancellation

Added in optional conversions and cancelling searches without just
closing the tab

.gitignore

@@ -1,3 +1,4 @@
 __pycache__
 .venv
 *.pdf
+*.db

docker-compose.yml

@@ -6,4 +6,11 @@ services:
     environment:
       - HOST=0.0.0.0
       - PORT=8000
+      # Stored solves live on the mounted volume so they survive restarts.
+      - DB_PATH=/data/solves.db
+    volumes:
+      - solves:/data
     restart: unless-stopped
+
+volumes:
+  solves:

index.html

@@ -372,8 +372,21 @@
         <button class="mini" type="button" onclick="addConversion()">+ conversion</button>
     </fieldset>
 
+    <fieldset>
+        <legend>Optional conversions</legend>
+        <p class="help">An optional conversion <b>is</b> a choice for the optimizer &mdash; it may
+            apply the conversion (spending <b>from amount</b> of one resource to yield <b>to amount</b>
+            of another on the given turn) or refrain entirely. <b>Max count</b> lets it apply the
+            conversion up to that many times on the turn. The chosen counts appear in the solution and
+            the CSV download.
+        </p>
+        <div id="optional_conversions" class="cards"></div>
+        <button class="mini" type="button" onclick="addOptionalConversion()">+ optional conversion</button>
+    </fieldset>
+
     <p>
         <button id="solveBtn" class="primary" type="button" onclick="run()">Solve</button>
+        <button id="cancelBtn" type="button" onclick="cancelSolve()" style="display:none;margin-left:.4rem">Cancel</button>
         <span id="busy" class="help" style="margin-left:.6rem"></span>
     </p>
 
@@ -764,6 +777,37 @@
             document.getElementById("conversions").append(card);
         }
 
+        // --- optional conversions ---
+        // Unlike a forced conversion, the optimizer chooses how many times (0..max
+        // count) to apply this on its turn, or skips it entirely.
+        function addOptionalConversion(c = {}) {
+            const card = el("div", {class: "card"});
+            const from = selectEl(RESOURCES, c.from || "trade_goods");
+            const fromAmt = num(c.from_amount ?? c.amount ?? 1, {min: 0});
+            const to = selectEl(RESOURCES, c.to || "capital");
+            const toAmt = num(c.to_amount ?? c.amount ?? 1, {min: 0});
+            const maxCount = num(c.max_count ?? 1, {min: 1});
+            const turn = turnSelect(c.turn);
+            card._get = () => {
+                const o = {
+                    from: from.value, to: to.value,
+                    from_amount: +fromAmt.value, to_amount: +toAmt.value,
+                    max_count: +maxCount.value,
+                };
+                if (turn.value !== "") o.turn = +turn.value;
+                return o;
+            };
+            card.append(
+                field("From", from),
+                field("From amount", fromAmt),
+                field("To", to),
+                field("To amount", toAmt),
+                field("Max count", maxCount),
+                field("Turn (blank=final)", turn),
+                el("div", {class: "card-actions"}, removeBtn(card)));
+            document.getElementById("optional_conversions").append(card);
+        }
+
         // --- parsing helpers ---
         function parseInts(s) {
             const out = s.split(",").map(x => x.trim()).filter(Boolean).map(Number);
@@ -803,6 +847,7 @@
                 objective: {terms: collect("terms")},
                 resource_constraints: collect("constraints"),
                 conversions: collect("conversions"),
+                optional_conversions: collect("optional_conversions"),
             };
         }
 
@@ -831,6 +876,25 @@
         // so we don't cancel a solve the user backgrounds and comes back to).
         window.addEventListener("pagehide", cancelActiveSolve);
 
+        // Cancel this tab's in-flight solve without closing the tab: POST /cancel
+        // so the server stops the search. The running /solve then returns with the
+        // best plan found so far (or an empty/infeasible one), which run() renders.
+        function cancelSolve() {
+            if (!activeToken) return;
+            const btn = document.getElementById("cancelBtn");
+            btn.disabled = true;
+            btn.textContent = "Cancelling…";
+            fetch("/cancel?token=" + encodeURIComponent(activeToken), {method: "POST"})
+                .catch(() => {/* the solve still returns; nothing to do here */});
+        }
+        // Toggle the Cancel button's visibility, resetting its label/disabled state.
+        function showCancel(visible) {
+            const btn = document.getElementById("cancelBtn");
+            btn.style.display = visible ? "" : "none";
+            btn.disabled = false;
+            btn.textContent = "Cancel";
+        }
+
         async function run() {
             const errBox = document.getElementById("error");
             const out = document.getElementById("output");
@@ -849,6 +913,7 @@
             const token = (crypto.randomUUID ? crypto.randomUUID()
                 : String(Date.now()) + Math.random());
             activeToken = token;
+            showCancel(true);
             try {
                 const resp = await fetch("/solve", {
                     method: "POST",
@@ -862,9 +927,9 @@
                 }
                 const data = await resp.json();
                 if (!resp.ok) {pending.remove(); errBox.textContent = data.error || "Server error"; return;}
-                renderSolution(data, pending);
+                renderSolution(data, pending, token);
             } catch (e) {pending.remove(); errBox.textContent = e.message;}
-            finally {solvingHere = false; activeToken = null; setSolveDisabled(false);}
+            finally {solvingHere = false; activeToken = null; showCancel(false); setSolveDisabled(false);}
         }
 
         // Enable/disable the Solve button with an optional note beside it. `kind`
@@ -891,7 +956,7 @@
         setInterval(pollStatus, 1000);
         pollStatus();
 
-        function renderSolution(s, placeholder) {
+        function renderSolution(s, placeholder, token) {
             // Collapse any previously-shown solutions so the new one is the focus.
             for (const d of document.querySelectorAll("#output details.solution")) d.open = false;
 
@@ -900,6 +965,19 @@
             details.append(el("summary", {},
                 `Solution ${n} — ${s.status}, objective ${s.objective_value ?? "—"}`));
             const out = details;
+
+            // A shareable permalink to this stored solve, looked up by its UUID.
+            if (token) {
+                const url = location.origin + location.pathname + "?solve=" + encodeURIComponent(token);
+                out.append(el("p", {}, el("button", {
+                    class: "mini", type: "button",
+                    onclick: (ev) => {
+                        navigator.clipboard?.writeText(url);
+                        ev.target.textContent = "Link copied!";
+                        setTimeout(() => {ev.target.textContent = "Copy share link";}, 1500);
+                    },
+                }, "Copy share link")));
+            }
             out.append(el("p", {
                 html:
                     `<b>Status:</b> ${s.status} &nbsp; <b>Objective:</b> ${s.objective_value ?? "—"} &nbsp; ` +
@@ -951,6 +1029,15 @@
                         [c.turn, c.from, fmtNum(c.from_amount), c.to, fmtNum(c.to_amount)])));
             }
 
+            if (s.optional_conversions && s.optional_conversions.length) {
+                out.append(el("h3", {}, "Optional conversions (chosen)"));
+                out.append(gridTable(
+                    ["Turn", "Count", "From", "From amount", "To", "To amount"],
+                    s.optional_conversions.map(c =>
+                        [c.turn, c.count, c.from, fmtNum(c.from_amount * c.count),
+                        c.to, fmtNum(c.to_amount * c.count)])));
+            }
+
             // Swap the finished card in for this request's placeholder.
             if (placeholder) placeholder.replaceWith(details);
             else document.getElementById("output").prepend(details);
@@ -1038,6 +1125,19 @@
                         `${fmtNum(c.to_amount)} ${c.to} (turn ${c.turn})`
                 });
             }
+            // Optional conversions the optimizer chose: one row each, totalling the
+            // chosen count of applications spending `from` and yielding `to`.
+            for (const c of (s.optional_conversions || [])) {
+                const fromTotal = c.from_amount * c.count, toTotal = c.to_amount * c.count;
+                const d = {};
+                d[c.from] = (d[c.from] || 0) - fromTotal;
+                d[c.to] = (d[c.to] || 0) + toTotal;
+                push({
+                    turn: c.turn, deltas: d,
+                    summary: `convert ${fmtNum(fromTotal)} ${c.from} → ` +
+                        `${fmtNum(toTotal)} ${c.to} (turn ${c.turn})`
+                });
+            }
 
             // The solver only guarantees resources are non-negative at the END of
             // each Turn, so the raw (turn, city) order can momentarily overdraw a
@@ -1096,6 +1196,27 @@
             "brass": 1,
             "electrum": 2
         })
+
+        // --- deep link: /?solve=<uuid> loads a previously stored solve ---
+        async function loadSharedSolve(token) {
+            const out = document.getElementById("output");
+            const errBox = document.getElementById("error");
+            const pending = el("p", {class: "pending"}, "Loading shared solve…");
+            out.prepend(pending);
+            try {
+                const resp = await fetch("/solve/" + encodeURIComponent(token), {cache: "no-store"});
+                if (resp.status === 404) {
+                    pending.remove();
+                    errBox.textContent = "No stored solve found for that link (it may have been evicted).";
+                    return;
+                }
+                const rec = await resp.json();
+                if (!resp.ok) {pending.remove(); errBox.textContent = rec.error || "Server error"; return;}
+                renderSolution(rec.solution, pending, rec.token);
+            } catch (e) {pending.remove(); errBox.textContent = e.message;}
+        }
+        const sharedToken = new URLSearchParams(location.search).get("solve");
+        if (sharedToken) loadSharedSolve(sharedToken);
     </script>
 </body>
 

main.py

@@ -16,10 +16,12 @@ import json
 import os
 import select
 import socket
+import sqlite3
 import threading
+import time
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 from pathlib import Path
-from urllib.parse import parse_qs, urlsplit
+from urllib.parse import parse_qs, unquote, urlsplit
 
 from solve import problem_from_dict, solve, solution_to_dict
 
@@ -27,17 +29,84 @@ from solve import problem_from_dict, solve, solution_to_dict
 # The UI is a single static page served from index.html next to this module.
 INDEX_HTML = (Path(__file__).resolve().parent / "index.html").read_text(encoding="utf-8")
 
+# Completed solves are persisted to SQLite so they can be looked up later by
+# their UUID (GET /solve/<uuid>) and shared via /?solve=<uuid> deep links. Point
+# DB_PATH at a mounted volume so history survives container restarts/redeploys.
+# Old rows are evicted so the DB stays bounded (keep the newest MAX_SOLVES).
+DB_PATH = os.environ.get(
+    "DB_PATH", str(Path(__file__).resolve().parent / "data" / "solves.db"))
+MAX_SOLVES = int(os.environ.get("MAX_SOLVES", "500"))
+
+
+def _db():
+    conn = sqlite3.connect(DB_PATH, timeout=5.0)
+    # WAL lets the concurrent /solve/<uuid> readers run alongside a writer.
+    conn.execute("PRAGMA journal_mode=WAL")
+    conn.execute("PRAGMA busy_timeout=5000")
+    return conn
+
+
+def init_db():
+    Path(DB_PATH).parent.mkdir(parents=True, exist_ok=True)
+    conn = _db()
+    try:
+        with conn:
+            conn.execute(
+                "CREATE TABLE IF NOT EXISTS solves ("
+                "token TEXT PRIMARY KEY, ts REAL NOT NULL, status TEXT, "
+                "problem TEXT NOT NULL, solution TEXT NOT NULL)")
+            conn.execute("CREATE INDEX IF NOT EXISTS idx_solves_ts ON solves(ts)")
+    finally:
+        conn.close()
+
+
+def store_solve(token, problem, solution):
+    # token is client-generated; skip blanks. INSERT OR REPLACE means a repeated
+    # token overwrites (a client could clobber its own/another's row — acceptable
+    # for this app; switch to a server-issued id if that ever matters).
+    if not token:
+        return
+    conn = _db()
+    try:
+        with conn:
+            conn.execute(
+                "INSERT OR REPLACE INTO solves (token, ts, status, problem, solution) "
+                "VALUES (?, ?, ?, ?, ?)",
+                (token, time.time(), solution.get("status"),
+                 json.dumps(problem), json.dumps(solution)))
+            conn.execute(
+                "DELETE FROM solves WHERE token NOT IN "
+                "(SELECT token FROM solves ORDER BY ts DESC LIMIT ?)",
+                (MAX_SOLVES,))
+    finally:
+        conn.close()
+
+
+def fetch_solve(token):
+    conn = _db()
+    try:
+        row = conn.execute(
+            "SELECT token, ts, status, problem, solution FROM solves WHERE token = ?",
+            (token,)).fetchone()
+    finally:
+        conn.close()
+    if row is None:
+        return None
+    return {"token": row[0], "ts": row[1], "status": row[2],
+            "problem": json.loads(row[3]), "solution": json.loads(row[4])}
+
 # Only one solve may run at a time across all viewers. While it's held, other
 # clients get an immediate 429 from /solve and disable their button (they learn
 # the busy state by polling /status).
 _solve_lock = threading.Lock()
 
-# Tracks the in-flight solve so /cancel can stop it. When a tab closes, the
+# Tracks the in-flight solve so /cancel can stop it. /cancel is hit two ways:
-# browser fires navigator.sendBeacon("/cancel?token=...") — a normal small
+# the user clicking Cancel (a normal fetch, tab stays open) and a closing tab
-# request that survives the close and passes cleanly through reverse proxies,
+# firing navigator.sendBeacon("/cancel?token=...") — both small requests that
-# unlike a dropped upstream socket (which the proxy keeps alive). Guarded by
+# pass cleanly through reverse proxies, unlike a dropped upstream socket (which
-# _active_lock; only one solve runs at a time, but the lock keeps the token /
+# the proxy keeps alive). Guarded by _active_lock; only one solve runs at a
-# solver handoff race-free against a concurrent /cancel.
+# time, but the lock keeps the token / solver handoff race-free against a
+# concurrent /cancel.
 _active_lock = threading.Lock()
 _active = {"token": None, "solver": None}
 
@@ -63,10 +132,18 @@ class Handler(BaseHTTPRequestHandler):
         self.wfile.write(body)
 
     def do_GET(self):
-        if self.path in ("/", "/index.html"):
+        path = urlsplit(self.path).path
+        if path in ("/", "/index.html"):
             self._send(200, INDEX_HTML, "text/html; charset=utf-8")
-        elif self.path == "/status":
+        elif path == "/status":
             self._send(200, json.dumps({"solving": _solve_lock.locked()}), no_cache=True)
+        elif path.startswith("/solve/"):
+            token = unquote(path[len("/solve/"):])
+            rec = fetch_solve(token)
+            if rec is None:
+                self._send(404, json.dumps({"error": "not found"}), no_cache=True)
+            else:
+                self._send(200, json.dumps(rec), no_cache=True)
         else:
             self._send(404, json.dumps({"error": "not found"}))
 
@@ -99,7 +176,8 @@ class Handler(BaseHTTPRequestHandler):
         try:
             length = int(self.headers.get("Content-Length", 0))
             payload = json.loads(self.rfile.read(length) or b"{}")
-            problem = problem_from_dict(payload.get("problem", {}))
+            raw_problem = payload.get("problem", {})
+            problem = problem_from_dict(raw_problem)
             max_time = float(payload.get("max_time_seconds", 30.0))
             token = str(payload.get("token") or "")
 
@@ -143,7 +221,11 @@ class Handler(BaseHTTPRequestHandler):
 
             if "err" in result:
                 raise result["err"]
-            self._send(200, json.dumps(solution_to_dict(result["sol"])))
+            sol_dict = solution_to_dict(result["sol"])
+            # Persist the completed solve so it can be looked up by its UUID.
+            # (Cancelled solves take the early return above and aren't stored.)
+            store_solve(token, raw_problem, sol_dict)
+            self._send(200, json.dumps(sol_dict))
         except Exception as exc:  # surface errors to the browser
             self._send(400, json.dumps({"error": f"{type(exc).__name__}: {exc}"}))
         finally:
@@ -155,9 +237,10 @@ class Handler(BaseHTTPRequestHandler):
                 _solve_lock.release()
 
     def _handle_cancel(self, query):
-        # Stop the in-flight solve iff the beacon's token matches it, so a closing
+        # Stop the in-flight solve iff the request's token matches it, so a Cancel
-        # tab can't cancel a *different* viewer's solve. The running /solve handler
+        # click (or closing tab) can't cancel a *different* viewer's solve. The
-        # then returns normally and releases the lock.
+        # running /solve handler then returns normally — with the best plan found
+        # so far — and releases the lock.
         token = (query.get("token") or [""])[0]
         stopped = False
         with _active_lock:
@@ -171,6 +254,7 @@ class Handler(BaseHTTPRequestHandler):
 
 
 def main():
+    init_db()
     host = os.environ.get("HOST", "127.0.0.1")
     port = int(os.environ.get("PORT", "8000"))
     server = ThreadingHTTPServer((host, port), Handler)

solve.py

@@ -384,6 +384,14 @@ class Problem:
     # Turns are 0-indexed (None or omitted => final Turn); ``amount`` may be given
     # as a shorthand for an equal ``from_amount``/``to_amount`` (1-for-1).
     conversions: list[dict] = field(default_factory=list)
+    # Optional resource conversions the optimizer MAY apply on a given Turn (or
+    # refrain from), unlike the forced ``conversions`` above. Each one is offered
+    # up to ``max_count`` times (default 1): the model chooses an integer
+    # 0..max_count of applications, each spending ``from_amount`` of one resource
+    # and yielding ``to_amount`` of another on that Turn. Same entry shape as
+    # ``conversions`` plus an optional ``max_count``; Turns are 0-indexed
+    # (None/omitted => final Turn).
+    optional_conversions: list[dict] = field(default_factory=list)
 
 
 # --------------------------------------------------------------------------- #
@@ -418,6 +426,9 @@ class Solution:
     # Forced (caller-specified, non-optimizer) conversions that were applied:
     # list of {turn, from, to, from_amount, to_amount}.
     forced_conversions: list[dict] = field(default_factory=list)
+    # Optional conversions the optimizer chose to apply (count > 0): list of
+    # {turn, from, to, from_amount, to_amount, count}.
+    optional_conversions: list[dict] = field(default_factory=list)
     # Resource amounts at the END of each turn: list of {turn, <resource>: amount}.
     resources_by_turn: list[dict] = field(default_factory=list)
 
@@ -485,6 +496,7 @@ class _Builder:
         self._build_city_dynamics()
         self._build_trade_conversion()
         self._build_conversions()
+        self._build_optional_conversions()
         self._build_onetime_governor_bonuses()
         self._build_resource_balance()
         self._build_provisioner_electrum()
@@ -1026,10 +1038,18 @@ class _Builder:
             found_active = type_active[CityType.FOUNDRY][t]
             found_collect = self._mul_bool(collect, found_active, 1)
             # choose which vat to collect (at most one, only if found_collect)
+            # A vat may only be collected if it is non-empty: collecting an
+            # empty vat (level 0) is disallowed. When every vat is empty the
+            # Foundry therefore cannot Collect this Turn (found_collect == 0).
             pick = {}
             for r in vat_res:
                 pick[r] = m.NewBoolVar(f"vatpick_{ci}_{r}_t{t}")
                 m.Add(pick[r] <= found_collect)
+                # nonempty[r] == 1 iff vat[r][t] >= 1.
+                nonempty = m.NewBoolVar(f"vatnonempty_{ci}_{r}_t{t}")
+                m.Add(vat[r][t] >= 1).OnlyEnforceIf(nonempty)
+                m.Add(vat[r][t] == 0).OnlyEnforceIf(nonempty.Not())
+                m.Add(pick[r] <= nonempty)
             m.Add(sum(pick[r] for r in vat_res) == found_collect)
             self._vat_choice[(ci, t)] = pick
 
@@ -1149,6 +1169,48 @@ class _Builder:
                 "from_amount": from_amt, "to_amount": to_amt,
             })
 
+    def _build_optional_conversions(self):
+        """Optional (optimizer-chosen) resource conversions on specific Turns.
+
+        Unlike the forced ``conversions``, each of these is a *decision*: the
+        model picks an integer count in ``0..max_count`` of how many times to
+        apply it on its Turn, spending ``from_amount`` per application of one
+        resource and yielding ``to_amount`` of another. A count of 0 means the
+        conversion is simply skipped. The non-negative resource balance still
+        forces the spent resource to be available whenever count > 0."""
+        m = self.m
+        # Parallel to self.conversions: meta dict + the chosen-count IntVar.
+        self.optional_conversions: list[dict] = []
+        self._opt_conv_vars: list[tuple[dict, cp_model.IntVar]] = []
+        for i, c in enumerate(self.p.optional_conversions):
+            t_in = c.get("turn")
+            t = self.T - 1 if t_in is None else int(t_in)
+            if not (0 <= t < self.T):
+                raise ValueError(
+                    f"optional conversion turn {t_in} out of range 0..{self.T - 1}")
+            src, dst = c["from"], c["to"]
+            if src not in RESOURCES:
+                raise ValueError(f"optional conversion 'from' unknown resource: {src!r}")
+            if dst not in RESOURCES:
+                raise ValueError(f"optional conversion 'to' unknown resource: {dst!r}")
+            amount = c.get("amount")
+            from_amt = int(round(c.get("from_amount", amount if amount is not None else 0)))
+            to_amt = int(round(c.get("to_amount", amount if amount is not None else from_amt)))
+            if from_amt < 0 or to_amt < 0:
+                raise ValueError("optional conversion amounts must be non-negative")
+            max_count = int(c.get("max_count", 1))
+            if max_count < 1:
+                raise ValueError("optional conversion max_count must be >= 1")
+            n = m.NewIntVar(0, max_count, f"optconv{i}_t{t}")
+            self._add_delta(src, t, -from_amt * n)
+            self._add_delta(dst, t, to_amt * n)
+            meta = {
+                "turn": t, "from": src, "to": dst,
+                "from_amount": from_amt, "to_amount": to_amt, "max_count": max_count,
+            }
+            self.optional_conversions.append(meta)
+            self._opt_conv_vars.append((meta, n))
+
     def _build_onetime_governor_bonuses(self):
         """Courier: the first Turn the Agent governs any City, grant a one-time
         ``{resource: amount}`` bonus. Added to the resource deltas before the
@@ -1468,6 +1530,15 @@ def _extract(problem: Problem, b: _Builder, solver, status_name: str) -> Solutio
         amt = solver.Value(var)
         if amt:
             conversions.append({"turn": t, "resource": r, "amount": amt})
+    optional_conversions = []
+    for meta, n in b._opt_conv_vars:
+        count = int(solver.Value(n))
+        if count:
+            optional_conversions.append({
+                "turn": meta["turn"], "from": meta["from"], "to": meta["to"],
+                "from_amount": meta["from_amount"], "to_amount": meta["to_amount"],
+                "count": count,
+            })
     resources_by_turn = []
     for t in range(T):
         row = {"turn": t}
@@ -1483,6 +1554,7 @@ def _extract(problem: Problem, b: _Builder, solver, status_name: str) -> Solutio
         plan=sorted(plan, key=lambda p: (p.turn, p.city)),
         trade_conversions=conversions,
         forced_conversions=list(b.conversions),
+        optional_conversions=optional_conversions,
         resources_by_turn=resources_by_turn,
     )