#793 Add a kb set-default command for the default knowledge base

packages/kb/README.md

@@ -54,7 +54,7 @@ kbs:
     description: Shared team knowledge base
 ```
 
-The top-level `default_kb` key names the machine's default knowledge base — the single KB that search and writes fall back on when no store is named or discovered. It must name an entry under `kbs`; a value that matches none fails the load.
+The top-level `default_kb` key names the machine's default knowledge base: the single KB that search and writes fall back on when no store is named or discovered. It must name an entry under `kbs`; a value that matches none fails the load. Set, change, or clear it from the command line with `kb set-default`.
 
 Configuration keys, per KB entry under `kbs.<name>`:
 
@@ -186,7 +186,7 @@ Matching uses dotfile-insensitive globbing, so dot-directories (`.kb`, `.git`, `
 
 ## The `kb` command
 
-The package ships a `kb` bin with two subcommands: `create` and `check`.
+The package ships a `kb` bin with three subcommands: `create`, `set-default`, and `check`.
 
 ### kb create
 
@@ -211,6 +211,18 @@ The schema and config seeds are serialized from the in-package `defaultSchema` a
 
 The name defaults to the directory's base name; `--name` overrides it and `--no-register` scaffolds without writing the registry. The registry write preserves any existing comments in `kb.yaml`. `kb create` refuses to clobber: it exits 2 if the directory already contains a `.kb/` store, or if the chosen name is already registered.
 
+### kb set-default
+
+`kb set-default` sets, clears, or interactively chooses the user-global default knowledge base: the top-level `default_kb` pointer in `~/.agents/kb.yaml`.
+
+```bash
+kb set-default coding   # set default_kb to the registered KB "coding"
+kb set-default --none   # clear default_kb
+kb set-default          # list the registered KBs and choose interactively
+```
+
+With a name, it sets `default_kb` to that KB, exiting 2 if the name is not registered. With `--none`, it clears the pointer. With no arguments on an interactive terminal, it lists the registered KBs — marking the current default and offering a `(none)` option — and writes the choice; cancelling with an empty line leaves the registry unchanged. With no arguments on a non-interactive stdin, it exits 2 rather than hanging. Writes resolve against and target the user-global registry only, and preserve existing comments and formatting.
+
 ### kb check
 
 `kb check` validates a store's notes and reports the findings. With no path arguments it checks every note; path arguments or `--vs` scope the run to a subset.

packages/kb/src/cli/__tests__/select-kb-prompt.test.ts

@@ -0,0 +1,54 @@
+import { describe, expect, it } from 'vitest';
+
+import type { KbRegistryEntry } from '../../types.ts';
+import { formatKbSelection, parseSelection } from '../select-kb-prompt.ts';
+
+const entries: KbRegistryEntry[] = [
+  { name: 'coding', path: '/abs/coding', source: 'user' },
+  { name: 'notes', path: '/abs/notes', source: 'user' },
+];
+
+describe(formatKbSelection, () => {
+  it('numbers each KB and appends a (none) option', () => {
+    const text = formatKbSelection(entries);
+
+    expect(text).toContain('1) coding');
+    expect(text).toContain('2) notes');
+    expect(text).toContain('3) (none) — no default');
+  });
+
+  it('marks the current default', () => {
+    const text = formatKbSelection(entries, 'notes');
+
+    expect(text).toContain('2) notes  (current default)');
+    expect(text).not.toContain('coding  (current default)');
+  });
+
+  it('marks (none) as current when no default is set', () => {
+    const text = formatKbSelection(entries, undefined);
+
+    expect(text).toContain('(none) — no default  (current)');
+  });
+});
+
+describe(parseSelection, () => {
+  it('treats an empty answer as cancel', () => {
+    expect(parseSelection('', 2)).toEqual({ kind: 'cancel' });
+  });
+
+  it('maps an in-range number to a 0-based KB index', () => {
+    expect(parseSelection('1', 2)).toEqual({ kind: 'kb', index: 0 });
+    expect(parseSelection('2', 2)).toEqual({ kind: 'kb', index: 1 });
+  });
+
+  it('maps the trailing number to none', () => {
+    expect(parseSelection('3', 2)).toEqual({ kind: 'none' });
+  });
+
+  it('returns null for out-of-range or non-numeric input', () => {
+    expect(parseSelection('0', 2)).toBeNull();
+    expect(parseSelection('4', 2)).toBeNull();
+    expect(parseSelection('abc', 2)).toBeNull();
+    expect(parseSelection('1.5', 2)).toBeNull();
+  });
+});

packages/kb/src/cli/__tests__/set-default.test.ts

@@ -0,0 +1,182 @@
+import { describe, expect, it } from 'vitest';
+
+import { loadKbRegistry } from '../../discovery/load-registry.ts';
+import { getRegistryPathFor, makeTempDir, seedRegistry } from '../../test-utils/scaffolding.ts';
+import { run } from '../run.ts';
+import type { SelectKbChoice, SelectKbPrompt } from '../select-kb-prompt.ts';
+
+const TWO_KBS = 'kbs:\n  coding:\n    path: /abs/coding\n  notes:\n    path: /abs/notes\n';
+
+describe('kb set-default <name>', () => {
+  it('sets default_kb to the named KB and confirms', async () => {
+    const home = await makeSeededHome(TWO_KBS);
+
+    const result = await run({ argv: ['set-default', 'notes'], cwd: home, home });
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stdout).toBe('Default knowledge base has been set to "notes".\n');
+    const config = await loadKbRegistry({ userConfigPath: getRegistryPathFor(home) });
+    expect(config.defaultKb?.name).toBe('notes');
+  });
+
+  it('exits 2 and leaves the registry unchanged when the name is not registered', async () => {
+    const home = await makeSeededHome(`default_kb: coding\n${TWO_KBS}`);
+
+    const result = await run({ argv: ['set-default', 'missing'], cwd: home, home });
+
+    expect(result.exitCode).toBe(2);
+    expect(result.stderr).toContain('not a registered knowledge base');
+    const config = await loadKbRegistry({ userConfigPath: getRegistryPathFor(home) });
+    expect(config.defaultKb?.name).toBe('coding');
+  });
+
+  it('sets the current default again idempotently', async () => {
+    const home = await makeSeededHome(`default_kb: coding\n${TWO_KBS}`);
+
+    const result = await run({ argv: ['set-default', 'coding'], cwd: home, home });
+
+    expect(result.exitCode).toBe(0);
+    const config = await loadKbRegistry({ userConfigPath: getRegistryPathFor(home) });
+    expect(config.defaultKb?.name).toBe('coding');
+  });
+});
+
+describe('kb set-default --none', () => {
+  it('clears default_kb and confirms', async () => {
+    const home = await makeSeededHome(`default_kb: coding\n${TWO_KBS}`);
+
+    const result = await run({ argv: ['set-default', '--none'], cwd: home, home });
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stdout).toBe('The default knowledge base has been cleared.\n');
+    const config = await loadKbRegistry({ userConfigPath: getRegistryPathFor(home) });
+    expect(config.defaultKb).toBeUndefined();
+  });
+
+  it('succeeds when no default is set', async () => {
+    const home = await makeSeededHome(TWO_KBS);
+
+    const result = await run({ argv: ['set-default', '--none'], cwd: home, home });
+
+    expect(result.exitCode).toBe(0);
+  });
+
+  it('exits 2 when combined with a name', async () => {
+    const home = await makeSeededHome(TWO_KBS);
+
+    const result = await run({ argv: ['set-default', 'coding', '--none'], cwd: home, home });
+
+    expect(result.exitCode).toBe(2);
+  });
+});
+
+describe('kb set-default (interactive)', () => {
+  it('sets the picked KB and reports the current default to the picker', async () => {
+    const home = await makeSeededHome(`default_kb: coding\n${TWO_KBS}`);
+    const { prompt, calledWith } = stubPrompt({ kind: 'kb', index: 1 });
+
+    const result = await run({ argv: ['set-default'], cwd: home, home, selectKb: prompt });
+
+    expect(result.exitCode).toBe(0);
+    expect(calledWith[0]?.currentDefaultName).toBe('coding');
+    const config = await loadKbRegistry({ userConfigPath: getRegistryPathFor(home) });
+    expect(config.defaultKb?.name).toBe('notes');
+  });
+
+  it('clears the default when (none) is chosen', async () => {
+    const home = await makeSeededHome(`default_kb: coding\n${TWO_KBS}`);
+    const { prompt } = stubPrompt({ kind: 'none' });
+
+    const result = await run({ argv: ['set-default'], cwd: home, home, selectKb: prompt });
+
+    expect(result.exitCode).toBe(0);
+    const config = await loadKbRegistry({ userConfigPath: getRegistryPathFor(home) });
+    expect(config.defaultKb).toBeUndefined();
+  });
+
+  it('leaves the registry unchanged when cancelled', async () => {
+    const home = await makeSeededHome(`default_kb: coding\n${TWO_KBS}`);
+    const { prompt } = stubPrompt({ kind: 'cancel' });
+
+    const result = await run({ argv: ['set-default'], cwd: home, home, selectKb: prompt });
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stdout).toBe('No changes made.\n');
+    const config = await loadKbRegistry({ userConfigPath: getRegistryPathFor(home) });
+    expect(config.defaultKb?.name).toBe('coding');
+  });
+
+  it('exits 2 when stdin is not interactive (no picker supplied)', async () => {
+    const home = await makeSeededHome(TWO_KBS);
+
+    const result = await run({ argv: ['set-default'], cwd: home, home });
+
+    expect(result.exitCode).toBe(2);
+    expect(result.stderr).toContain('not interactive');
+  });
+});
+
+describe('kb set-default error and help paths', () => {
+  it('exits 2 directing to kb create when no KBs are registered (name form)', async () => {
+    const home = await makeTempDir('kb-setdefault-home-');
+
+    const result = await run({ argv: ['set-default', 'coding'], cwd: home, home });
+
+    expect(result.exitCode).toBe(2);
+    expect(result.stderr).toContain('kb create');
+  });
+
+  it('exits 2 directing to kb create when no KBs are registered (interactive form)', async () => {
+    const home = await makeTempDir('kb-setdefault-home-');
+    const { prompt } = stubPrompt({ kind: 'cancel' });
+
+    const result = await run({ argv: ['set-default'], cwd: home, home, selectKb: prompt });
+
+    expect(result.exitCode).toBe(2);
+    expect(result.stderr).toContain('kb create');
+  });
+
+  it('exits 2 on an unknown flag', async () => {
+    const home = await makeSeededHome(TWO_KBS);
+
+    const result = await run({ argv: ['set-default', '--bogus'], cwd: home, home });
+
+    expect(result.exitCode).toBe(2);
+  });
+
+  it('prints command help with --help', async () => {
+    const result = await run({ argv: ['set-default', '--help'], cwd: '/tmp', home: '/tmp' });
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stdout).toContain('kb set-default');
+  });
+
+  it('lists set-default in the top-level help', async () => {
+    const result = await run({ argv: [], cwd: '/tmp', home: '/tmp' });
+
+    expect(result.stdout).toContain('set-default');
+  });
+});
+
+// region | Helpers
+
+/** Creates a temp home directory whose `kb.yaml` registry is seeded with `content`, and returns its path. */
+async function makeSeededHome(content: string): Promise<string> {
+  const home = await makeTempDir('kb-setdefault-home-');
+  await seedRegistry(getRegistryPathFor(home), content);
+  return home;
+}
+
+/** A stub picker that returns a fixed choice and records the input it was called with. */
+function stubPrompt(choice: SelectKbChoice): { prompt: SelectKbPrompt; calledWith: { currentDefaultName?: string }[] } {
+  const calledWith: { currentDefaultName?: string }[] = [];
+  const prompt: SelectKbPrompt = (input) => {
+    calledWith.push({
+      ...(input.currentDefaultName !== undefined && { currentDefaultName: input.currentDefaultName }),
+    });
+    return Promise.resolve(choice);
+  };
+  return { prompt, calledWith };
+}
+
+// endregion | Helpers