Remove unnecessary seeded RNG

diegochine · diegochine · commit d6a014277129 · 2026-02-05T20:23:32.000+01:00
diff --git a/AGENTS.md b/AGENTS.md
@@ -20,7 +20,6 @@ The Probability Lab helps students understand:
 - Two events mode: joint heatmap + two-way table with joint/conditional reads
 - Bias controls: fair vs biased devices (coin, die, spinner; custom devices are configured via
   `config.json`)
-- Seeded randomness: reproduce runs with a seed
 - Event relationships: independent, dependent
 - Custom devices: define up to 50 outcomes + probabilities in `config.json`
 
@@ -185,10 +184,10 @@ Experiment summary:
 Settings modal:
 
 - pl-settings-modal
-- pl-settings-section-probabilities, pl-settings-section-event, pl-settings-section-randomness
+- pl-settings-section-probabilities, pl-settings-section-event
 - pl-single-config, pl-two-config
 - pl-bias-options, pl-bias-options-a, pl-bias-options-b
-- pl-relationship, pl-seed
+- pl-relationship
 
 Controls:
 
diff --git a/README.md b/README.md
@@ -7,7 +7,6 @@ A Bespoke Simulation for repeated-trial probability experiments (coin, die, spin
 - **One event mode**: event builder (select outcomes), live bar chart, convergence chart, frequency table
 - **Two events mode**: joint heatmap + two-way table; click a cell to see joint and conditional probabilities
 - **Bias controls**: explore fair vs biased devices
-- **Seeded randomness**: optionally reproduce runs with a seed
 
 ## Development
 
@@ -30,4 +29,3 @@ npm run start:prod
 - `client/app.js` – simulation engine + rendering
 - `client/app.css` – app-specific styling
 - `client/help-content.html` – Help modal content
-
diff --git a/client/app.js b/client/app.js
@@ -6,7 +6,6 @@ import { loadConfig } from './src/shell/config.js';
 import { createActivityLogger } from './src/shell/activity-logger.js';
 import { clamp, safeNumber } from './src/shared/math.js';
 import { formatProbability } from './src/shared/format.js';
-import { createRngFromSeed } from './src/probability-lab/domain/rng.js';
 import { buildDeviceDefinition } from './src/probability-lab/domain/devices.js';
 import simulateSingleTrials from './src/probability-lab/engine/simulate-single.js';
 import simulateTwoTrials from './src/probability-lab/engine/simulate-two.js';
@@ -53,8 +52,6 @@ const els = {
   runModeToggleManual: $('pl-run-mode-toggle-manual'),
   runModeToggleAuto: $('pl-run-mode-toggle-auto'),
 
-  seed: $('pl-seed'),
-
   eventOutcomes: $('pl-event-outcomes'),
 
   deviceView: $('pl-device-view'),
@@ -101,18 +98,7 @@ let settingsModal = null;
 let historyModal = null;
 let historyView = null;
 
-/**
- * Generates a random numeric seed string for the RNG
- * @returns {string} A random seed value as a string
- */
-function generateRandomSeed() {
-  return Math.floor(Math.random() * 100000000).toString();
-}
-
 const store = createStore({
-  rng: Math.random,
-  seedText: '',
-  userSpecifiedSeed: false,
 
   mode: 'single',
   speed: 60,
@@ -274,12 +260,6 @@ function resetSimulation({ reason = 'unknown', logSettings = false } = {}) {
   runner.stopRunning();
   store.setState((draft) => {
     draft.running.cancel = false;
-    // Generate new random seed on reset if user hasn't specified one
-    if (!draft.userSpecifiedSeed) {
-      draft.seedText = generateRandomSeed();
-    }
-    // Rewind RNG to the start of the seeded sequence on every reset
-    draft.rng = createRngFromSeed(draft.seedText);
   });
 
   const state = store.getState();
@@ -427,7 +407,6 @@ function updateControls() {
   const toDisable = [
     els.spinnerSectors,
     els.stepSize,
-    els.seed,
     els.relationship,
     els.openSettings,
   ];
@@ -770,23 +749,6 @@ function renderEventOptions() {
   }
 }
 
-function applySeed(seedText) {
-  const trimmed = (seedText ?? '').trim();
-  store.setState((draft) => {
-    if (trimmed === '') {
-      // User cleared the seed - revert to auto-generation
-      draft.userSpecifiedSeed = false;
-      draft.seedText = generateRandomSeed();
-    } else {
-      // User specified a seed - mark as user-specified and persist it
-      draft.userSpecifiedSeed = true;
-      draft.seedText = trimmed;
-    }
-    draft.rng = createRngFromSeed(draft.seedText);
-  });
-  resetSimulation({ reason: 'seed_change', logSettings: true });
-}
-
 function openSettingsModal(scrollTarget) {
   if (!settingsModal) return;
 
@@ -862,7 +824,6 @@ function initHistoryModal() {
 function syncUiFromState() {
   const state = store.getState();
   els.stepSize.value = String(state.stepSize);
-  els.seed.value = state.seedText;
 
   els.spinnerSectors.value = String(state.single.spinnerSectors);
 
@@ -1038,7 +999,7 @@ function initEventListeners() {
   els.step.addEventListener('click', () => {
     const state = store.getState();
     const stateSlice = state.mode === 'two' ? state.two : state.single;
-    runner.runTrials(state.stepSize, state.mode, simulateSingleTrials, simulateTwoTrials, stateSlice, state.rng);
+    runner.runTrials(state.stepSize, state.mode, simulateSingleTrials, simulateTwoTrials, stateSlice, Math.random);
   });
 
   els.reset.addEventListener('click', () => {
@@ -1051,25 +1012,10 @@ function initEventListeners() {
       runner.stopRunning();
     } else {
       const stateSlice = state.mode === 'two' ? state.two : state.single;
-      runner.startAuto(state.mode, simulateSingleTrials, simulateTwoTrials, stateSlice, state.rng, state.speed);
+      runner.startAuto(state.mode, simulateSingleTrials, simulateTwoTrials, stateSlice, Math.random, state.speed);
     }
   });
 
-  // Apply seed automatically on change
-  let seedTimeout = null;
-  els.seed.addEventListener('input', () => {
-    // Debounce to avoid resetting simulation too frequently during typing
-    clearTimeout(seedTimeout);
-    seedTimeout = setTimeout(() => {
-      applySeed(els.seed.value);
-    }, 500);
-  });
-
-  els.seed.addEventListener('change', () => {
-    clearTimeout(seedTimeout);
-    applySeed(els.seed.value);
-  });
-
   els.twoWayTable.addEventListener('click', (event) => {
     const cell = event.target.closest('[data-row][data-col]');
     if (!cell) return;
@@ -1157,12 +1103,6 @@ async function init() {
     if (config.visualElements) {
       draft.visualElements = { ...draft.visualElements, ...config.visualElements };
     }
-    // Generate random seed at startup if seedText is empty
-    if (!draft.seedText || draft.seedText.trim() === '') {
-      draft.seedText = generateRandomSeed();
-      draft.userSpecifiedSeed = false;
-    }
-    draft.rng = createRngFromSeed(draft.seedText);
   });
   syncUiFromState();
 
@@ -1191,7 +1131,7 @@ async function init() {
           setTimeout(() => {
             const newState = store.getState();
             const stateSlice = newState.mode === 'two' ? newState.two : newState.single;
-            runner.startAuto(newState.mode, simulateSingleTrials, simulateTwoTrials, stateSlice, newState.rng, newState.speed);
+            runner.startAuto(newState.mode, simulateSingleTrials, simulateTwoTrials, stateSlice, Math.random, newState.speed);
           }, 0);
         }
       },
diff --git a/client/help-content.html b/client/help-content.html
@@ -25,19 +25,17 @@ <h2>Overview</h2>
 
   <h3>Competencies</h3>
   <ul>
-    <li>Identifies probability as a measure of likelihood</li>
-    <li>Describes outcomes and sample spaces</li>
-    <li>Estimates event frequency from real or simulated data</li>
-    <li>Compares probabilities</li>
-    <li>Interprets relationships between events using tables or diagrams</li>
+    <li>Identify probability as a measure of likelihood</li>
+    <li>Describe outcomes and sample spaces</li>
+    <li>Estimate event frequency from real or simulated data</li>
+    <li>Compare probabilities</li>
+    <li>Interpret relationships between events using tables or diagrams</li>
   </ul>
 </section>
 
 <section id="getting-started">
   <h2>Getting Started</h2>
   <ol>
-    <li><strong>Choose a mode:</strong> <em>One event</em> (single sample space) or <em>Two events</em> (two-way table).</li>
-    <li><strong>Pick a device</strong> (coin / die / spinner / custom) and optionally adjust its bias.</li>
     <li><strong>Define Event E</strong> by selecting outcomes (e.g., “Heads”, or “Even” by selecting 2, 4, 6).</li>
     <li><strong>Run trials</strong> using <em>Run</em>, the +1/+10/+100/+1000 buttons, or <em>Start auto</em>.</li>
     <li><strong>Interpret the results</strong> using the charts and tables (look at how the estimates stabilize as trials increase).</li>
@@ -57,41 +55,19 @@ <h3>Frequency Table</h3>
   <p>Lists theoretical probability, count, relative frequency, and the difference (<strong>Δ</strong>) between experiment and theory for each outcome. Selected outcomes (Event E) are highlighted.</p>
 
   <h3>Two Events: Heatmap + Two-way Table</h3>
-  <p>Switch to <em>Two events</em> to explore joint outcomes. Click a cell to see:</p>
+  <p>Click a cell in the heatmap to see:</p>
   <ul>
     <li><strong>P(A ∩ B)</strong> (joint probability estimate)</li>
     <li><strong>P(A | B)</strong> and <strong>P(B | A)</strong> (conditional probability estimate)</li>
     <li>An "independence check" comparing <strong>P(A)·P(B)</strong> to <strong>P(A ∩ B)</strong></li>
   </ul>
 
-  <h3>Seeded Runs</h3>
-  <p>Use a <strong>seed</strong> to repeat the same random sequence and compare runs.</p>
-</section>
-
-<section id="workflow">
-  <h2>Learning Workflow</h2>
-  <p>Use these short tasks to build intuition quickly:</p>
-  <ol>
-    <li><strong>Sample space:</strong> Choose a device and list its outcomes (e.g., die: 1–6).</li>
-    <li><strong>Event building:</strong> Define an event (e.g., “Even” on a die) by selecting outcomes.</li>
-    <li><strong>Convergence:</strong> Run 10, 100, 1,000 trials. Describe how the estimate changes.</li>
-    <li><strong>Comparing probabilities:</strong> Change the device bias (e.g., increase P(6)) and predict what will happen before running.</li>
-    <li><strong>Relationships:</strong> In two-event mode, compare <em>Independent</em> vs <em>Dependent</em>. Explain what changes in the two-way table.</li>
-  </ol>
-
-  <h3>Tips & Best Practices</h3>
-  <ul>
-    <li>Small samples are noisy on purpose—don’t “fix” the randomness.</li>
-    <li>If you change the device bias, treat it as a new experiment and reset.</li>
-    <li>Use the tables to justify claims (don’t rely only on what “feels” likely).</li>
-  </ul>
 </section>
 
 <section id="shortcuts">
   <h2>Shortcuts</h2>
   <ul>
     <li><strong>ESC</strong> - Close help modal</li>
-    <li><strong>Enter</strong> (in the Seed input) - Apply seed</li>
     <li><strong>Click a heatmap/two-way cell</strong> - Show joint + conditional probabilities</li>
   </ul>
 </section>
@@ -123,9 +99,4 @@ <h2>Troubleshooting / FAQ</h2>
     <summary>What should I look for in the two-way table?</summary>
     <p>Start with the joint counts. Then click a cell to compare <strong>P(A ∩ B)</strong> to <strong>P(A)·P(B)</strong>. If events are independent, these values should be close (with enough trials).</p>
   </details>
-
-  <details>
-    <summary>Is anything saved?</summary>
-    <p>The lab saves basic settings (mode, device choices, bias sliders, event selection, seed) in your browser so you can continue where you left off. Trial results are not persisted.</p>
-  </details>
 </section>
diff --git a/client/index.html b/client/index.html
@@ -229,17 +229,6 @@ <h3 class="heading-xxxsmall">Event B</h3>
             </label>
           </div>
         </section>
-
-        <section class="box pl-settings-section" id="pl-settings-section-randomness">
-          <div class="pl-settings-section-header">
-            <h3 class="heading-xxxsmall">Random seed</h3>
-            <p class="pl-muted body-xsmall">Set a seed to reproduce the same results across runs.</p>
-          </div>
-
-          <label class="row">
-            <input id="pl-seed" class="input" type="number" placeholder="42" />
-          </label>
-        </section>
       </div>
 
       <div id="pl-single-view" class="pl-content-grid">
diff --git a/client/src/probability-lab/AGENTS.md b/client/src/probability-lab/AGENTS.md
@@ -23,7 +23,6 @@ Two-event mode (`state.two`):
 
 ## Domain
 
-- `domain/rng.js`: deterministic RNG utilities; empty seed returns `Math.random`.
 - `domain/cdf.js`: builds CDF and samples indexes.
 - `domain/devices.js`: builds device definitions and clamps probabilities.
   - Spinner sectors are clamped to 2-12.
diff --git a/client/src/probability-lab/domain/rng.js b/client/src/probability-lab/domain/rng.js
diff --git a/client/src/shell/activity-logger.js b/client/src/shell/activity-logger.js
@@ -49,7 +49,6 @@ function buildSettingsSnapshot(state) {
       deviceA: state.two.deviceA ?? null,
       deviceB: state.two.deviceB ?? null,
       sections,
-      seed: state.seedText ?? '',
       relationship: state.two.relationship ?? null,
       spinnerSectorsA: state.two.spinnerSectorsA ?? null,
       spinnerSectorsB: state.two.spinnerSectorsB ?? null,
@@ -71,7 +70,6 @@ function buildSettingsSnapshot(state) {
     mode: 'single',
     device: state.single.device ?? null,
     sections,
-    seed: state.seedText ?? '',
     spinnerSectors: state.single.spinnerSectors ?? null,
     bias: {
       coinProbabilities: cloneArray(state.single.coinProbabilities),
diff --git a/tests/AGENTS.md b/tests/AGENTS.md
@@ -9,7 +9,7 @@ Scope: Vitest suites under `tests/`.
 ## Structure
 
 - `tests/shared/` exercises `client/src/shared` utilities.
-- `tests/probability-lab/domain/` covers RNG, CDF, device definitions.
+- `tests/probability-lab/domain/` covers CDF, device definitions.
 - `tests/probability-lab/engine/` covers simulation functions.
   - Includes coverage for custom devices and dependent-mode behavior.
 
@@ -18,4 +18,3 @@ Scope: Vitest suites under `tests/`.
 - Use `.test.js` or `.spec.js` filenames (see `vitest.config.js`).
 - Vitest runs with `environment: \"node\"` (see `vitest.config.js`).
 - Import modules from `client/src` to test production logic.
-- Keep RNG-based tests deterministic by seeding where needed.
diff --git a/tests/probability-lab/domain/rng.test.js b/tests/probability-lab/domain/rng.test.js
