feat: edit managed-model context windows in Settings

AGENTS.md

@@ -124,6 +124,7 @@ lib/
   deferred-provider-models.ts models of providers an extension registers only at session_start, re-added to listings
   enabled-models.ts         pure minimal-edit engine for the enabledModels pattern list
   enabled-models-runtime.ts SDK adapter for enabledModels: pattern resolution, provider kinds, settings IO
+  model-context.ts          client-safe: managed models' contextWindow overrides in the models.json draft, the Save check
   subagent-settings.ts      read/write ~/.pi/agent/agents/settings.json
   file-access.ts            allowed file roots for /api/files and worktrees
   file-upload-client.ts     browser upload to /api/files ?type=upload, shared by the explorer and chat drops
@@ -192,6 +193,7 @@ components/
   MarkdownBody.tsx         markdown renderer
   ModelsConfig.tsx         Settings › Models: models.json editor
   EnabledModelsSection.tsx model switches inside ModelsConfig (enabledModels)
+  ModelContextWindow.tsx   a managed model row's context-window field (blank: no override)
   OAuthPastePanel.tsx      paste box for a sign-in's redirected address or code (Models, MCP)
   ProjectTrustDialog.tsx   trust confirmation listing the project's MCP servers
   AgentsConfig.tsx         built-in subagent toggle + agent profile editor
@@ -238,7 +240,7 @@ Design decisions and traps live in `docs/agents/`, one note per area. Read every
 - [mcp-settings.md](docs/agents/mcp-settings.md): Settings › MCP reads without running anything, masking, the trust dialog's server list, row states, notices, Code mode choice, trust from Settings, Escape stacking, every `mcp.json` write and undo. Files: `app/api/mcp/route.ts`, `app/api/project-trust/route.ts`, `lib/mcp-config-read.ts`, `lib/mcp-config-file.ts`, `lib/mcp-override.ts`, `lib/mcp-undo.ts`, `lib/mcp-secrets.ts`, `lib/mcp-server-display.ts`, `lib/mcp-json-error.ts`, `lib/project-trust.ts`, `lib/regular-file.ts`, `lib/stacked-dialog.ts`, `lib/settings-navigation.ts`, `components/McpConfig.tsx`, `components/mcp-config-helpers.ts`, `components/ProjectTrustDialog.tsx`, `components/SettingsPanel.tsx`.
 - [mcp-test-sign-in.md](docs/agents/mcp-test-sign-in.md): Settings › MCP Test (route checks, bounded connection, `!command` queue, redaction, status store) and OAuth sign-in / sign-out. Files: `app/api/mcp/test/**`, `app/api/mcp/sign-in/**`, `lib/mcp-test.ts`, `lib/mcp-entry-request.ts`, `lib/mcp-status.ts`, `lib/mcp-sign-in.ts`, `lib/mcp-sign-out.ts`, `components/McpSignIn.tsx`, `components/mcp-sign-in-helpers.ts`, `components/OAuthPastePanel.tsx`.
 - [mcp-add.md](docs/agents/mcp-add.md): Settings › MCP add (paste re-parsed on the server, host-variable confirmation, literal secrets kept global, fresh-folder trust, the add pane) and the paste importer's escaping and grammars. Files: `lib/mcp-add.ts`, `lib/mcp-import*.ts`, `lib/shell-words.ts`, fresh-folder trust in `lib/project-trust.ts`, `components/McpAddServer.tsx`, `components/mcp-add-helpers.ts`, the `add` action of `app/api/mcp/route.ts`.
-- [models.md](docs/agents/models.md): default model and reasoning level, providers registered at session_start, mid-run reasoning changes, remote provider catalogs, `enabledModels` scoping and minimal edits, provider auth listing and credentials. Files: `app/api/models/**`, `app/api/models-config/**`, `app/api/auth/**`, `lib/default-preferences.ts`, `lib/model-scope.ts`, `lib/enabled-models*.ts`, `lib/model-catalog-refresh.ts`, `lib/deferred-provider-models.ts`, `lib/provider-listing*.ts`, `components/ModelsConfig.tsx`, `components/EnabledModelsSection.tsx`, `components/ModelSelector.tsx`, `components/SelectorRow.tsx`.
+- [models.md](docs/agents/models.md): default model and reasoning level, providers registered at session_start, mid-run reasoning changes, remote provider catalogs, `enabledModels` scoping and minimal edits, managed models' context-window overrides, provider auth listing and credentials. Files: `app/api/models/**`, `app/api/models-config/**`, `app/api/auth/**`, `lib/default-preferences.ts`, `lib/model-scope.ts`, `lib/enabled-models*.ts`, `lib/model-context.ts`, `lib/model-catalog-refresh.ts`, `lib/deferred-provider-models.ts`, `lib/provider-listing*.ts`, `components/ModelsConfig.tsx`, `components/EnabledModelsSection.tsx`, `components/ModelContextWindow.tsx`, `components/ModelSelector.tsx`, `components/SelectorRow.tsx`.
 - [files-and-access.md](docs/agents/files-and-access.md): worktrees and project grouping, the file access allow-list (the `/api/files` security boundary), file tree visibility and its open directories per folder, uploads and chat file drops, the source view's languages by extension, the CSV/TSV table view, web password throttling. Files: `app/api/files/**`, `app/api/cwd/**`, `app/api/worktrees/**`, `app/api/file-index/**`, `app/api/web-auth/**`, `proxy.ts`, `lib/path-security.ts`, `lib/file-access.ts`, `lib/linked-directory.ts`, `lib/session-file-references*.ts`, `lib/file-tree-visibility.ts`, `lib/file-tree-expansion.ts`, `lib/file-upload-client.ts`, `lib/worktree.ts`, `lib/paths.ts`, `lib/auth-throttle.ts`, `components/ProjectWorktreePicker.tsx`, `components/NewSessionContextBar.tsx`, `components/FileExplorer.tsx`, `lib/delimited-table.ts`, `components/DelimitedTable.tsx`, the table branch of `components/FileViewer.tsx`, `hooks/useDragDrop.ts`.
 - [settings-ui.md](docs/agents/settings-ui.md): General's sidebar file-browser choice, Plugins and Skills routes, sidebar group switches, the shared `SettingsUi` blocks every settings panel and add pane uses. Files: `app/api/plugins/**`, `app/api/skills/**`, `components/SettingsUi.tsx`, `components/settings-ui-helpers.ts`, `components/SkillsConfig.tsx`, `components/PluginsConfig.tsx`, `hooks/useFilesPlacement.ts`; also before adding a settings section or add pane.
 - [subagents.md](docs/agents/subagents.md): the built-in subagent setting, profiles and their files, run status, completion notifications, the subagent viewer tab. Files: `lib/subagent*.ts`, `app/api/subagents/**`, `components/AgentsConfig.tsx`, `components/SubagentViewer.tsx`, `components/subagent-viewer-state.ts`.

app/api/models-config/route.test.mjs

@@ -52,3 +52,52 @@ test("a commented models.json loads with its providers", async () => {
   assert.equal(response.status, 200);
   assert.deepEqual(await response.json(), { providers: { acme: { models: [{ id: "a" }] } } });
 });
+
+test("invalid context overrides are rejected without changing the saved configuration", async () => {
+  const config = { providers: { "openai-codex": { modelOverrides: { "gpt-6-astra": { contextWindow: 500000 } } } } };
+  await writeFile(modelsPath, JSON.stringify(config));
+  const invalid = structuredClone(config);
+  invalid.providers["openai-codex"].modelOverrides["gpt-6-astra"].contextWindow = 0;
+  const response = await PUT(put(invalid));
+  assert.equal(response.status, 400);
+  assert.deepEqual(await (await GET()).json(), config);
+});
+
+test("saved login-model context overrides reach the SDK; resetting restores the catalog without changing credentials", async () => {
+  const { ModelRuntime } = await import("@earendil-works/pi-coding-agent");
+  const authPath = join(testAgentDir, "auth.json");
+  const credentials = JSON.stringify({ "openai-codex": { type: "oauth", access: "test-only", refresh: "test-only", expires: 9999999999999 } });
+  await writeFile(authPath, credentials);
+  const options = { authPath, modelsPath, modelsStorePath: join(testAgentDir, "models-store.json"), refreshOnCreate: false };
+  const config = { providers: { "openai-codex": { modelOverrides: { "gpt-6-astra": { contextWindow: "500000", maxTokens: 128000 } } } } };
+  assert.equal((await PUT(put(config))).status, 200);
+  const saved = await (await GET()).json();
+  assert.equal(saved.providers["openai-codex"].modelOverrides["gpt-6-astra"].contextWindow, 500000);
+  const runtime = await ModelRuntime.create(options);
+  assert.equal(runtime.getModel("openai-codex", "gpt-6-astra").contextWindow, 500000);
+  delete config.providers["openai-codex"].modelOverrides["gpt-6-astra"].contextWindow;
+  assert.equal((await PUT(put(config))).status, 200);
+  const reset = await ModelRuntime.create(options);
+  const baseline = await ModelRuntime.create({ ...options, modelsPath: null });
+  assert.equal(reset.getModel("openai-codex", "gpt-6-astra").contextWindow, baseline.getModel("openai-codex", "gpt-6-astra").contextWindow);
+  assert.equal(reset.getModel("openai-codex", "gpt-6-astra").maxTokens, 128000);
+  assert.equal(await readFile(authPath, "utf8"), credentials);
+});
+
+test("a hand-edited override pi accepts does not block saving an unrelated provider", async () => {
+  const { ModelRuntime } = await import("@earendil-works/pi-coding-agent");
+  const config = { providers: {
+    "openai-codex": { modelOverrides: { "gpt-6-astra": { contextWindow: 400000.5 } } },
+    relay: { baseUrl: "http://127.0.0.1:1/v1", api: "openai-completions", apiKey: "TEST_ONLY_KEY", models: [{ id: "a" }] },
+  } };
+  await writeFile(modelsPath, JSON.stringify(config));
+  const options = { authPath: join(testAgentDir, "auth.json"), modelsPath, modelsStorePath: join(testAgentDir, "models-store.json"), refreshOnCreate: false };
+  const runtime = await ModelRuntime.create(options);
+  assert.equal(runtime.getError(), undefined);
+  assert.equal(runtime.getModel("openai-codex", "gpt-6-astra").contextWindow, 400000.5);
+  const edited = structuredClone(config);
+  edited.providers.relay.models.push({ id: "b" });
+  const response = await PUT(put(edited));
+  assert.equal(response.status, 200);
+  assert.deepEqual(await (await GET()).json(), edited);
+});

app/api/models-config/route.ts

@@ -1,5 +1,6 @@
 import { NextResponse } from "next/server";
 import { ModelsConfigReadError, readModelsConfig, writeModelsConfig } from "@/lib/models-config-store";
+import { ContextWindowError, normalizeContextWindowOverrides } from "@/lib/model-context";
 
 export const dynamic = "force-dynamic";
 
@@ -17,9 +18,12 @@ export async function GET() {
 export async function PUT(req: Request) {
   try {
     const body = await req.json() as Record<string, unknown>;
-    writeModelsConfig(body);
+    writeModelsConfig(normalizeContextWindowOverrides(body));
     return NextResponse.json({ success: true });
   } catch (error) {
+    if (error instanceof ContextWindowError) {
+      return NextResponse.json({ error: error.message }, { status: 400 });
+    }
     if (error instanceof ModelsConfigReadError) {
       return NextResponse.json({ error: error.message }, { status: 409 });
     }

app/settings.css

@@ -430,6 +430,32 @@
   border-top: 1px solid var(--border);
 }
 
+/* Eight digits wide (ch follows the phones' 16px form text), and no taller
+   than the name and id beside it, so the row keeps its height. */
+.model-context-input {
+  flex-shrink: 0;
+  width: calc(8ch + 16px);
+  height: 24px;
+  box-sizing: border-box;
+  padding: 0 7px;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  background: var(--bg);
+  color: var(--text);
+  font-family: var(--font-mono);
+  font-size: 11px;
+  text-align: right;
+}
+
+.model-context-input:focus-visible {
+  outline: 2px solid var(--accent);
+  outline-offset: 1px;
+}
+
+.model-context-input::placeholder { color: var(--text-dim); }
+.model-context-input[aria-invalid="true"] { border-color: #ef4444; }
+.model-context-input:disabled { opacity: 0.6; }
+
 .enabled-models-row-text {
   min-width: 0;
   flex: 1;

components/EnabledModelsSection.tsx

@@ -11,6 +11,7 @@ import {
   isLastEnabledModel,
 } from "./enabled-models-helpers";
 import { ConfigButton, ConfigSwitch } from "./SettingsUi";
+import { ModelContextWindow, type ModelContextSettings } from "./ModelContextWindow";
 
 /**
  * Model switches backed by pi's `enabledModels` setting.
@@ -361,9 +362,11 @@ function useCatalogRefresh(providerId: string, onChanged: () => void) {
 export function EnabledModelsSection({
   providerId,
   controller,
+  contextSettings,
 }: {
   providerId: string;
   controller: EnabledModelsController;
+  contextSettings?: ModelContextSettings;
 }) {
   const { t } = useI18n();
   const [query, setQuery] = useState("");
@@ -392,6 +395,7 @@ export function EnabledModelsSection({
   const editable = view?.editable === true;
   const scopeNoteId = `${noteId}-scope`;
   const lastModelNoteId = `${noteId}-last`;
+  const contextNoteId = `${noteId}-context`;
   const disableBlockedByLastModel = editable && !bulk.canDisable && bulk.disableRefs.length > 0;
   const showLastModelNote = disableBlockedByLastModel || (editable && shown.some((model) => isLastEnabledModel(view, model)));
   // A provider-wide action is resolved server-side so models the browser has
@@ -453,11 +457,15 @@ export function EnabledModelsSection({
           className="enabled-models-filter"
         />
       )}
+      {contextSettings && <div id={contextNoteId} className="enabled-models-note">{t("models.contextOverrideHelp")}</div>}
       <div className="enabled-models-list">
         {shown.length === 0 ? (
           <div className="enabled-models-empty">{t("models.enabledNoMatches")}</div>
         ) : shown.map((model) => {
           const lastOne = isLastEnabledModel(view, model);
+          const override = contextSettings?.overrides?.[model.id];
+          const contextValue = override && typeof override === "object" && !Array.isArray(override)
+            ? (override as Record<string, unknown>).contextWindow : undefined;
           return (
             <div key={model.ref} className="enabled-models-row">
               <span className="enabled-models-row-text">
@@ -469,6 +477,16 @@ export function EnabledModelsSection({
                   {model.thinkingPin}
                 </span>
               )}
+              {contextSettings && (
+                <ModelContextWindow
+                  modelName={model.name}
+                  effective={model.contextWindow}
+                  value={contextValue}
+                  disabled={contextSettings.disabled}
+                  describedBy={contextNoteId}
+                  onChange={(value) => contextSettings.onChange(model.id, value)}
+                />
+              )}
               <ConfigSwitch
                 checked={model.enabled}
                 loading={pending === model.ref}

components/ModelContextWindow.test.mjs

@@ -0,0 +1,32 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { createElement } from "react";
+import { renderToStaticMarkup } from "react-dom/server";
+import { createJiti } from "jiti";
+
+const jiti = createJiti(import.meta.url, { tsconfigPaths: true, jsx: { runtime: "automatic" } });
+const { ModelContextWindow } = await jiti.import("./ModelContextWindow.tsx");
+const { I18nProvider } = await jiti.import("@/hooks/useI18n");
+
+function render(value) {
+  return renderToStaticMarkup(createElement(I18nProvider, null,
+    createElement(ModelContextWindow, { modelName: "GPT Example", effective: 272000, value, onChange() {} })));
+}
+
+test("a login model's row gets one named input whose placeholder is the window pi resolves", () => {
+  const blank = render(undefined);
+  assert.match(blank, /^<input [^>]*\/>$/, "no label, button or note beside the input");
+  assert.match(blank, /value=""/);
+  assert.match(blank, /placeholder="272000"/);
+  assert.match(blank, /inputmode="numeric"/i);
+  assert.match(blank, /aria-label="Context window for GPT Example"/);
+  assert.match(render("500000"), /value="500000"/);
+});
+
+test("a typed draft that is not a whole number is marked without being truncated", () => {
+  const html = render("500k");
+  assert.match(html, /value="500k"/);
+  assert.match(html, /aria-invalid="true"/);
+  // A value pi accepts in models.json is not flagged, though the field would not take it typed.
+  assert.doesNotMatch(render(400000.5), /aria-invalid/);
+});

components/ModelContextWindow.tsx

@@ -0,0 +1,41 @@
+"use client";
+
+import { useI18n } from "@/hooks/useI18n";
+import { parseContextWindow } from "@/lib/model-context";
+
+export interface ModelContextSettings {
+  overrides?: Record<string, unknown>;
+  disabled: boolean;
+  onChange: (modelId: string, value: string | undefined) => void;
+}
+
+/**
+ * Like custom-model fields, this edits the Models panel's draft, not the file.
+ * Blank means no override; the placeholder is the window pi resolves now.
+ */
+export function ModelContextWindow({ modelName, effective, value, onChange, disabled = false, describedBy }: {
+  modelName: string;
+  effective?: number;
+  value: unknown;
+  onChange: (value: string | undefined) => void;
+  disabled?: boolean;
+  describedBy?: string;
+}) {
+  const { t } = useI18n();
+  const invalid = value !== undefined && parseContextWindow(value) === undefined;
+  return (
+    <input
+      type="text"
+      inputMode="numeric"
+      className="model-context-input"
+      value={value === undefined ? "" : String(value)}
+      placeholder={effective === undefined ? undefined : String(effective)}
+      title={t("models.contextWindow")}
+      aria-label={t("models.contextForModel", { model: modelName })}
+      aria-invalid={invalid || undefined}
+      aria-describedby={describedBy}
+      disabled={disabled}
+      onChange={(event) => onChange(event.target.value.trim() === "" ? undefined : event.target.value)}
+    />
+  );
+}