Release v0.3.1 [skip release] [skip actions]

The user's declaration is keyed by session id, and a session spawned or forked
from a scoped one has none of its own — so its facet was its own working
directory, one level above its parent's. Delegation was therefore a way around
the scope rather than work inside it: the parent could not read the file itself
and could have a subagent read it.

A session now inherits the root resolved for the session named by its
`parentSession` header, which the harness already records durably for both a
spawned child and a fork. The inherited root is the parent's *effective* root, so
it already includes any narrowing the parent made for itself: delegating is not
a way back out of a self-imposed focus either. Because each session records its
own root as it resolves a scope, and a scope is resolved for every model request
and every tool call, inheritance holds at any depth of delegation rather than for
one hop.

Two boundaries are deliberate. A declaration the user made *for the child* is a
more specific statement about that session and stands — inheritance only answers
the case where they made none. And a parent's recorded root outlives its session
while any child that inherited it is still running, because disposing a parent
must not quietly widen a subagent that is still working.

CHANGELOG.md

@@ -2,6 +2,15 @@
 
 Every release, newest first, generated from the commits in each release.
 
+## v0.3.1 — 2026-09-27
+
+### Fixed
+
+- a delegated session inherits the facet it was spawned under
+- judge a search that names no path against the directory it would use
+- name the allowed-paths action for what it adds, a path or a file
+
+
 ## v0.3.0 — 2026-09-27
 
 ### Added

README.md

@@ -48,6 +48,15 @@ wrong, and an agent that cannot reach a shared type does not stop needing it.
 So an out-of-scope file call is put to you, and saying yes records the grant for
 the rest of the conversation.
 
+**A tool that names no path is judged on the path it would use.** `grep`, `glob`
+and `recall` all default to a directory when the model omits one — the session
+directory for the first two, a marker-chosen one for the third — and on a session
+whose facet is narrower than its directory, that default reads outside the facet.
+An absent argument is not an absent path, so those three are judged against the
+default they would have searched, and the refusal says which argument to add.
+`lib/scope.js` holds the list; a tool with no path argument at all is still left
+alone, because it has no default that could leave.
+
 ### The `facet` tool
 
 | action | effect |
@@ -145,6 +154,15 @@ and your root otherwise. So an agent that goes wrong cannot widen its own scope,
 and `facet action=reset` returns it to what you declared rather than to the
 session directory — landing on the directory would have made `reset` a widening.
 
+**A session spawned or forked from a scoped one inherits its root.** Your
+declaration is keyed by session id, and a subagent or a fork has none of its own,
+so without this its facet would be its own working directory — one level up, and
+a way to delegate around the scope rather than work inside it. The inherited root
+already includes the parent's own narrowing, so delegating is not a way back out
+of a focus the agent set for itself either, and it is recorded per level, so it
+holds at any depth of delegation. It applies only where you made no statement:
+a declaration for the child session is the more specific answer and stands.
+
 You set the declaration from the **crosshair button on the composer tool row**,
 which appears only in sessions running the `facet` preset. It shows the focus and
 the allowed paths, adds and removes them, and carries the mode details and usage
@@ -161,7 +179,8 @@ a breadcrumb trail, a hidden-entries toggle — driven through
 stored in the form that keeps its meaning: `/work/root/src/shared` becomes
 `src/shared` when the session started in `/work/root`. The picker's own path field
 stays editable, because the Host lists folders and an extra may legitimately name
-a file.
+a file — which is why that action reads **Add path or file** and its field **Path
+or file**, rather than promising a folder the list would then fail to show.
 
 Because the panel owns widening, `facet action=add` is the *other* path and the
 narrower one: it is gated on an approval channel, and a deployment with none — the
@@ -207,7 +226,10 @@ Honest boundaries, because each one is a decision rather than an oversight:
 - **`bash` is not guarded.** A shell command cannot be judged reliably from
   argv, so the facet is enforced on the file tools and `bash` remains a
   legitimate way out. The prompt tells the model this rather than pretending
-  otherwise.
+  otherwise. It is not a theoretical hole: the first deployment to run this had
+  an agent scoped to one module use a shell command to parse a config file
+  outside its facet, having been told in the same prompt not to. A prompt is not
+  a guard, which is what the rest of this plugin is for.
 - **Tools that name a path in a shape the table cannot read are not guessed at** —
   including MCP tools. See `PATH_ARGUMENTS` in `lib/scope.js`; it is a list of
   tools whose path argument is a plain top-level string.
@@ -224,26 +246,31 @@ Honest boundaries, because each one is a decision rather than an oversight:
 
 Verified:
 
-- 73 tests (`npm test`) over the scope algebra, the policy state, the guard, and
+- 88 tests (`npm test`) over the scope algebra, the policy state, the guard, and
   the browser half — including that containment is decided on canonical targets
   (a symlink inside the facet pointing outside it is refused), that a prefix is
   not a parent (`/a/room` does not contain `/a/roommate`), that a malformed tool
   call never makes the guard throw, that a live `mode` edit decides the next call
   without the guard being remounted, that an agent narrowing the user has since
   narrowed past is dropped rather than honoured, that `reset` lands on the
-  declared scope rather than the session directory, and that every `facet` result
+  declared scope rather than the session directory, that a search naming no path
-  satisfies the tool's own declared output schema.
+  is refused when the directory it defaults to is outside the facet, that a
+  delegated session inherits its parent's root at any depth and is not a way back
+  out of a self-narrowing, and that every `facet` result satisfies the tool's own
+  declared output schema.
 - The bundle's patch layers parse, merge and land correctly against the real
   profile: `dsh --profile web --patch ./cordis.patch.yml --patch
   ./presets/facet.patch.yml --dump-config` shows `facet-policy`, `preset-facet`,
   the `facet-guard` row and the compaction config, with `preset-standard`
   untouched. The optional `standard-compaction` overlay was checked the same way.
 
-**Not yet verified: a live session.** The plugin has not been loaded by a running
+**Verified live.** The bundle is installed in a `web` profile and composing
-harness, because that needs the bundle installed. The first thing to check after
+sessions: the runtime binding is in the running session's context, the crosshair
-installing is that `preset-facet` is not `broken` — a preset whose child row
+panel writes the declaration, and the guard decides the calls it names. That is
-fails to resolve still appears on the roster, with its diagnostic, and cannot
+also where the `bash` boundary above was confirmed the hard way. The first thing
-compose a session:
+to check after any change is still that `preset-facet` is not `broken` — a preset
+whose child row fails to resolve still appears on the roster, with its
+diagnostic, and cannot compose a session:
 
 ```sh
 dsh --profile web --dump-config | grep -A 3 preset-facet
@@ -308,7 +335,7 @@ lib/scope.js                 the pure half — argument extraction, text, reason
 lib/guard.js                 preset row: rule, binding, tool, pre-execute guard
 presets/facet.patch.yml      the `facet` agent preset
 presets/standard-compaction.patch.yml   optional: the same budget for `standard`
-test/                        78 tests
+test/                        88 tests
 ```
 
 `client/client.js` is a browser half rather than a module the host imports, and

client/client.js

@@ -680,7 +680,7 @@ window.__ModuleLoader__.load({
       return h(Modal, {
         open: true,
         onClose,
-        title: target === 'focus' ? 'Choose the focus folder' : 'Add a folder or a path',
+        title: target === 'focus' ? 'Choose the focus folder' : 'Add a path or a file',
         closeLabel: 'Close',
         className: PICKER_CLASS,
         // One scroll region around everything but the footer, so the card is
@@ -694,7 +694,7 @@ window.__ModuleLoader__.load({
           h(
             'div',
             { key: 'path' },
-            h('label', { style: labelStyle, htmlFor: 'facet-picker-path' }, target === 'focus' ? 'Folder' : 'Path'),
+            h('label', { style: labelStyle, htmlFor: 'facet-picker-path' }, target === 'focus' ? 'Folder' : 'Path or file'),
             h('input', {
               id: 'facet-picker-path',
               type: 'text',
@@ -713,7 +713,16 @@ window.__ModuleLoader__.load({
                 model.open(typed)
               },
             }),
-            h('p', { style: hintStyle }, 'Relative to the session folder, or absolute. Enter lists whatever is there.'),
+            h(
+              'p',
+              { style: hintStyle },
+              target === 'focus'
+                ? 'Relative to the session folder, or absolute. Enter lists whatever is there.'
+                : // The list holds folders only — the Host's browse primitive has no
+                  // file rows — so the box is where a file is named, and saying so
+                  // is the difference between a dead end and an instruction.
+                  'Relative to the session folder, or absolute. The list holds folders; type a file\u2019s name to add the file itself.',
+            ),
           ),
           h(
             'div',
@@ -1015,7 +1024,7 @@ window.__ModuleLoader__.load({
                 h(
                   'button',
                   { type: 'button', style: quietButtonStyle, disabled: !canBrowse, onClick: () => openPicker('extra') },
-                  '+ Add folder or path\u2026',
+                  '+ Add path or file\u2026',
                 ),
               ),
               h(

lib/guard.js

@@ -37,6 +37,8 @@ import {
   FACET_TOOL,
   facetContextText,
   facetRuleText,
+  IMPLICIT_SESSION_PATHS,
+  implicitSearchReason,
   isWideningCall,
   outsideReason,
   pathArgumentsFor,
@@ -181,7 +183,20 @@ export function apply(ctx, config) {
     if (scope === undefined) return undefined
 
     const paths = pathArgumentsFor(exec.name, exec.arguments)
-    if (paths.length === 0) return undefined
+    if (paths.length === 0) {
+      // A tool that names no path is judged against the path it will actually
+      // use. For most of them that is nothing — a tool with no path argument
+      // cannot leave the facet. For the ones whose own default is a directory it
+      // is the session directory, which a narrowed facet does not contain, and
+      // "no opinion" there would hand the model a read the guard exists to
+      // refuse. The containment test is the same one; only the path is ours
+      // rather than the model's.
+      if (!IMPLICIT_SESSION_PATHS.includes(exec.name)) return undefined
+      const verdict = await inside(scope, scope.cwd, exec.signal)
+      if (verdict.inside) return undefined
+      const kind = mode === 'deny' ? 'deny' : 'ask'
+      return { kind, reason: implicitSearchReason({ cwd: scope.cwd, root: scope.root }) }
+    }
 
     for (const raw of paths) {
       const verdict = await inside(scope, raw, exec.signal)

lib/policy.js

@@ -97,6 +97,29 @@ export function createFacetPolicy(config) {
   const grants = new Map()
   /** @type {Map<string, string>} session id → the agent's narrowing focus, absolute. */
   const narrowed = new Map()
+  /**
+   * The root resolved for each session, recorded as it is computed.
+   *
+   * A session spawned or forked from this one has no declaration of its own, so
+   * without this its facet would be its own working directory — wider than the
+   * conversation it came from, which is the one direction this whole plugin
+   * promises cannot happen. The recorded root already includes the parent's own
+   * narrowing, so a child is never wider than the parent is *now*, and the
+   * record's existence is what makes the inheritance work per level rather than
+   * for one hop.
+   *
+   * @type {Map<string, string>} session id → the root in force for it.
+   */
+  const roots = new Map()
+  /**
+   * Child session id → the session it inherited from, for as long as both live.
+   *
+   * Kept so {@link forget} can tell a root nobody needs any more from one a
+   * delegated child is still answering to.
+   *
+   * @type {Map<string, string>}
+   */
+  const spawnedFrom = new Map()
 
   /**
    * What the user declared for one session, read fresh.
@@ -112,6 +135,23 @@ export function createFacetPolicy(config) {
     return entry !== null && typeof entry === 'object' ? entry : undefined
   }
 
+  /**
+   * The session this one was spawned or forked from, when the header says so.
+   *
+   * The harness's own durable lineage field, so the link survives a restart and
+   * a child whose parent is no longer running is still contained. `fork` records
+   * the session it was seeded from and a subagent its direct parent; both are
+   * one conversation's work continuing, which is what makes inheriting the right
+   * answer for either.
+   *
+   * @param {{session?: {header?: {parentSession?: unknown}}}|undefined} agent - the calling agent.
+   * @returns {string|undefined} the parent's session id.
+   */
+  function parentOf(agent) {
+    const parent = agent?.session?.header?.parentSession
+    return typeof parent === 'string' && parent !== '' ? parent : undefined
+  }
+
   /**
    * The root in force for one session.
    *
@@ -123,16 +163,22 @@ export function createFacetPolicy(config) {
    * place — this one only has to notice a root that has since moved out from
    * under it.
    *
+   * Inheritance is the same kind of test, and it is skipped when the user made a
+   * declaration of their own: that is their decision about *this* session, and
+   * the point of inheriting is to answer the case where they made none.
+   *
    * @param {string|undefined} sessionId - the session.
    * @param {string} sessionCwd - its resolved working directory.
+   * @param {string} [inherited] - the root of the session it came from, if known.
    * @returns {string} the absolute facet root.
    */
-  function rootFor(sessionId, sessionCwd) {
+  function rootFor(sessionId, sessionCwd, inherited) {
     const declared = declaredScope(sessionId)?.focus
-    const base = typeof declared === 'string' && declared.trim() !== '' ? resolve(sessionCwd, declared) : sessionCwd
+    const stated = typeof declared === 'string' && declared.trim() !== ''
+    const own = stated ? resolve(sessionCwd, declared) : sessionCwd
+    const base = !stated && inherited !== undefined && within(inherited, own) ? inherited : own
     const agentFocus = sessionId === undefined ? undefined : narrowed.get(sessionId)
-    if (agentFocus === undefined) return base
+    if (agentFocus !== undefined && within(agentFocus, base)) return agentFocus
-    if (agentFocus === base || agentFocus.startsWith(base.endsWith(sep) ? base : `${base}${sep}`)) return agentFocus
     return base
   }
 
@@ -162,7 +208,13 @@ export function createFacetPolicy(config) {
    * resolve against. A declaration written relative to the session keeps the
    * same meaning whatever the session is focused on.
    *
-   * @param {{session?: {header?: {cwd?: unknown}, id?: unknown}}|undefined} agent - the calling agent.
+   * Resolving a scope is also where a session's own root is *recorded*, which is
+   * what a session spawned from it later inherits. Every session resolves a
+   * scope before it can call anything — the binding is assembled for each model
+   * request, and the guard classifies each tool call — so a parent's root is
+   * always on the record by the time it can spawn or fork.
+   *
+   * @param {{session?: {header?: {cwd?: unknown, parentSession?: unknown}, id?: unknown}}|undefined} agent - the calling agent.
    * @returns {FacetScope|undefined} the scope.
    */
   function scopeFor(agent) {
@@ -170,9 +222,13 @@ export function createFacetPolicy(config) {
     if (typeof cwd !== 'string' || cwd.trim() === '') return undefined
     const sessionCwd = resolve(cwd)
     const sessionId = idOf(agent)
+    const parent = parentOf(agent)
+    if (sessionId !== undefined && parent !== undefined) spawnedFrom.set(sessionId, parent)
+    const root = rootFor(sessionId, sessionCwd, parent === undefined ? undefined : roots.get(parent))
+    if (sessionId !== undefined) roots.set(sessionId, root)
     return {
       cwd: sessionCwd,
-      root: rootFor(sessionId, sessionCwd),
+      root,
       extras: extrasFor(agent, sessionCwd),
     }
   }
@@ -284,10 +340,22 @@ export function createFacetPolicy(config) {
     return [...(grants.get(sessionId) ?? [])]
   }
 
-  /** Drop a finished session's grants. Called on `session/disposed`. */
+  /**
+   * Drop a finished session's state. Called on `session/disposed`.
+   *
+   * The root is the one entry that is not simply dropped: a session spawned from
+   * this one may still be running, and it answers to the facet it was spawned
+   * under. So the record is kept while any live session still records this one
+   * as its parent, and released the moment none does. Without that, disposing a
+   * parent would quietly widen its children back to their own directory.
+   *
+   * @param {string} sessionId - the session being disposed.
+   */
   function forget(sessionId) {
     grants.delete(sessionId)
     narrowed.delete(sessionId)
+    spawnedFrom.delete(sessionId)
+    if (![...spawnedFrom.values()].includes(sessionId)) roots.delete(sessionId)
   }
 
   return {
@@ -325,6 +393,25 @@ function isPath(value) {
   return typeof value === 'string' && value.trim() !== ''
 }
 
+/**
+ * Whether one absolute path is the other, or sits inside it.
+ *
+ * A string test, deliberately, and the only one in this module. The guard's
+ * containment check — the one that decides whether a *call* may proceed — runs
+ * on canonical filesystem targets, because a symlink inside the facet must not
+ * open it. This one only compares two roots the plugin itself derived from the
+ * session directory, where there is nothing to resolve and a symlink would have
+ * had to be introduced by the declaration.
+ *
+ * @param {string} inner - the path that may be inside.
+ * @param {string} outer - the path that may contain it.
+ * @returns {boolean} whether it is inside.
+ */
+function within(inner, outer) {
+  if (inner === outer) return true
+  return inner.startsWith(outer.endsWith(sep) ? outer : `${outer}${sep}`)
+}
+
 /**
  * The session id of a calling agent, when it has one.
  *

lib/scope.js

@@ -54,6 +54,28 @@ export const PATH_ARGUMENTS = Object.freeze({
   recall: ['path', 'focus'],
 })
 
+/**
+ * Tools that will search the session directory when the model names no path.
+ *
+ * The guard's rule is that a call naming no path is not judged, because a tool
+ * that names no path cannot leave the facet. That holds for a tool with no path
+ * argument at all, and fails for these three: their *own* default is the session
+ * workspace. `grep` and `glob` document both their path arguments as "Defaults to
+ * the session workspace", and `recall` falls back to a directory its own marker
+ * search picks — an ancestor of the facet whenever the facet carries no
+ * `CONTROLLER.md` of its own.
+ *
+ * So on any session whose facet is narrower than its directory — every session
+ * whose focus was set from the panel rather than by starting the conversation in
+ * the folder — a bare `grep` reads outside the facet. An absent argument is not
+ * an absent path; it is the default one, and that is the path the guard judges.
+ *
+ * `recall` is another package's tool and is named here because the coupling to
+ * its two path arguments already exists in {@link PATH_ARGUMENTS}: leaving it
+ * out would keep a read path the table claims to cover.
+ */
+export const IMPLICIT_SESSION_PATHS = Object.freeze(['grep', 'glob', 'recall'])
+
 /** The tool this plugin registers, and the action on it that widens the scope. */
 export const FACET_TOOL = 'facet'
 export const WIDENING_ACTION = 'add'
@@ -66,7 +88,10 @@ export const WIDENING_ACTION = 'add'
  * Anything that is not a non-empty string is skipped.
  *
  * An empty result means "no opinion" — either the tool names no path (so it
- * cannot leave the facet) or it names one in a shape we refuse to guess at.
+ * cannot leave the facet) or it names one in a shape we refuse to guess at. The
+ * first half of that is not true of every tool: the ones whose own default is a
+ * directory are listed in {@link IMPLICIT_SESSION_PATHS}, and the guard judges
+ * them against the directory they will actually search.
  *
  * @param {string} toolName - the tool being called.
  * @param {unknown} args - the raw model arguments.
@@ -236,6 +261,29 @@ export function outsideReason(input) {
   return `${what} is ${verb} — this session's facet is ${root}. Ask the user to grant it (\`facet action=add\`), or work within the facet.`
 }
 
+/**
+ * Why a search that named no directory is being questioned.
+ *
+ * A separate sentence from {@link outsideReason} because the fault is different.
+ * There, the model named a path outside the facet and is told which one. Here it
+ * named nothing, so the path at issue is one it never wrote: the tool's own
+ * default. Saying so is the whole remedy — the fix is a second argument, not a
+ * grant — so the reason names the directory the search would have covered and
+ * the one it had to stay in.
+ *
+ * @param {object} input
+ * @param {string} input.cwd - the session working directory the tool defaults to.
+ * @param {string} input.root - the facet root.
+ * @returns {string} the reason.
+ */
+export function implicitSearchReason(input) {
+  const { cwd, root } = input
+  return (
+    `This search names no \`path\`, so it would cover this session's directory ${cwd} — and this session's ` +
+    `facet is ${root}. Name a folder inside the facet, or ask the user to grant the one you need.`
+  )
+}
+
 /**
  * Why widening the scope is being put to the user.
  *

package.json

@@ -1,6 +1,6 @@
 {
   "name": "dsh-facet",
-  "version": "0.3.0",
+  "version": "0.3.1",
   "private": true,
   "type": "module",
   "description": "Scope an agent session to one facet of a multi-faceted system: the session's own folder, plus whatever files the user grants it.",

test/client.test.js

@@ -423,7 +423,7 @@ test('the panel renders the scope, the guidance, and a way to add and remove', a
   // already did.
   assert.ok(buttons.some((button) => labelOf(button) === 'Browse\u2026'))
   assert.ok(buttons.some((button) => labelOf(button) === 'Clear'))
-  assert.ok(buttons.some((button) => labelOf(button) === '+ Add folder or path\u2026'))
+  assert.ok(buttons.some((button) => labelOf(button) === '+ Add path or file\u2026'))
   assert.ok(!buttons.some((button) => labelOf(button) === 'Set'))
   assert.deepEqual(inputs, [], 'the panel itself has no free-text box left')
 })
@@ -456,7 +456,7 @@ test('a deployment with no directory browser keeps the panel and says so', async
   )
   assert.deepEqual(
     buttonsOf(tree)
-      .filter((button) => label(button) === '+ Add folder or path\u2026')
+      .filter((button) => label(button) === '+ Add path or file\u2026')
       .map((button) => button.props.disabled),
     [true],
   )
@@ -520,7 +520,10 @@ function walkTree(node, visit) {
   }
   visit(node)
   if (Array.isArray(node.children)) node.children.forEach((child) => walkTree(child, visit))
+  // `footer` is a prop rather than a child, and it is rendered: a control there
+  // is as much part of the tree as one in the body.
   walkTree(node.props?.children, visit)
+  walkTree(node.props?.footer, visit)
 }
 
 test('a path is declared relative to the session folder wherever it can be', async () => {
@@ -661,3 +664,37 @@ test('the picker lists folders, hides hidden ones until asked, and answers in de
   await settle()
 })
 
+test('the extras picker names what it accepts and says what the list holds', async () => {
+  const { module: mod } = await loadClient()
+
+  const model = new mod.DirectoryPickerModel({
+    list: () => Promise.resolve(listingFixture()),
+    root: '/work/root',
+    start: '/work/root/src',
+  })
+  await settle()
+
+  const tree = mod.DirectoryPicker({
+    model,
+    root: '/work/root',
+    target: 'extra',
+    disabled: false,
+    onClose: () => {},
+    onPick: () => {},
+  })
+
+  // "folder or path" promised one thing and offered another: the rows are
+  // folders, and a file is added by naming it. The copy says both.
+  assert.equal(tree.props.title, 'Add a path or a file')
+  const texts = textsOf(tree)
+  assert.ok(texts.includes('Path or file'), 'the field is named for what it accepts')
+  assert.ok(
+    texts.some((text) => text.includes('The list holds folders')),
+    'the copy explains why no file rows are shown',
+  )
+  assert.ok(
+    buttonsOf(tree).some((button) => (button.children ?? [])[0] === 'Add'),
+    'the action is Add for an extra, not Set focus',
+  )
+})
+

test/guard.test.js

@@ -170,13 +170,59 @@ test('a prefix is not a parent', async () => {
   assert.equal(decision.kind, 'ask')
 })
 
-test('an omitted path means the session directory, which is in scope', async () => {
+test('an omitted path means the session directory, which here is the facet', async () => {
   const { captured } = harness()
+  // Allowed because the default and the facet are the same folder — not because
+  // the call named nothing. The next test is the case where they differ.
   assert.deepEqual(await dispatch(captured, { name: 'glob', args: { pattern: '**/*.ts' }, agent: agent() }), {
     kind: 'allow',
   })
 })
 
+test('a search that names no path is judged against the directory it would cover', async () => {
+  // The session directory is the facet's parent here: the user narrowed this
+  // conversation to `inner`, while the search tools still default to the whole
+  // session directory. An absent argument is not an absent path — it is the
+  // default one, and the default one leaves the facet.
+  const { captured } = harness({ config: { mode: 'ask', scopes: { 'session-1': { focus: 'inner' } } } })
+
+  const decision = await dispatch(captured, { name: 'grep', args: { pattern: 'motion_learning' }, agent: agent() })
+  assert.equal(decision.kind, 'ask')
+  assert.match(decision.reason, /names no `path`/)
+  assert.match(decision.reason, /inner/, 'the reason names the boundary the call crossed')
+
+  // Naming the folder is the whole remedy, and it costs no grant.
+  assert.deepEqual(
+    await dispatch(captured, { name: 'grep', args: { pattern: 'x', path: 'inner' }, agent: agent() }),
+    { kind: 'allow' },
+  )
+  // The same rule reaches the other two tools whose default is a directory.
+  assert.equal(
+    (await dispatch(captured, { name: 'glob', args: { pattern: '**/*.ts' }, agent: agent() })).kind,
+    'ask',
+  )
+  assert.equal(
+    (await dispatch(captured, { name: 'recall', args: { query: 'motion learning' }, agent: agent() })).kind,
+    'ask',
+  )
+  // A tool with no path argument at all is still left alone: it has no default
+  // that could leave the facet.
+  assert.deepEqual(await dispatch(captured, { name: 'todo_write', args: { todos: [] }, agent: agent() }), {
+    kind: 'allow',
+  })
+})
+
+test('recall is judged on the scope it names, because that is what it will search', async () => {
+  const { captured } = harness({ config: { mode: 'deny', scopes: { 'session-1': { focus: 'inner' } } } })
+  assert.deepEqual(await dispatch(captured, { name: 'recall', args: { query: 'x', focus: 'inner' }, agent: agent() }), {
+    kind: 'allow',
+  })
+  assert.equal(
+    (await dispatch(captured, { name: 'recall', args: { query: 'x', path: '..' }, agent: agent() })).kind,
+    'deny',
+  )
+})
+
 test('tools the guard cannot judge are left alone, deliberately', async () => {
   const { captured } = harness()
   // A shell command cannot be read reliably from argv, so the facet is enforced
@@ -195,6 +241,84 @@ test('an agent with no working directory is not scoped', async () => {
   assert.deepEqual(await dispatch(captured, { name: 'read', args: { file_path: '/etc/hosts' } }), { kind: 'allow' })
 })
 
+// ── delegated sessions ───────────────────────────────────────────────────────
+//
+// A session spawned or forked from a scoped one has no declaration of its own,
+// and the user's declaration is keyed by session id. Without inheritance its
+// facet would be its own working directory — wider than the conversation it came
+// from, which is the one direction this plugin promises cannot happen.
+
+/** A session that was spawned from another, as the harness records lineage. */
+const childOf = (parentId, id = 'child-1', cwd = facet) => ({
+  session: { id, header: { cwd, parentSession: parentId } },
+})
+
+test('a session spawned from a scoped one starts inside the same facet', async () => {
+  const { captured } = harness({ config: { mode: 'ask', scopes: { 'session-1': { focus: 'inner' } } } })
+
+  // The parent's root is on the record as soon as it resolves a scope, which
+  // happens for every model request and every tool call — so before it can
+  // spawn anything.
+  assert.deepEqual(
+    await dispatch(captured, { name: 'read', args: { file_path: 'inner/index.ts' }, agent: agent() }),
+    { kind: 'allow' },
+  )
+
+  const child = childOf('session-1')
+  // Without inheritance this would be ordinary work for the child: its root
+  // would be the session directory, one level up from its parent's facet.
+  const decision = await dispatch(captured, { name: 'read', args: { file_path: 'index.ts' }, agent: child })
+  assert.equal(decision.kind, 'ask')
+  assert.match(decision.reason, /inner/)
+  // Inside the inherited facet is inside the child's scope, as it should be.
+  assert.deepEqual(
+    await dispatch(captured, { name: 'read', args: { file_path: 'inner/index.ts' }, agent: child }),
+    { kind: 'allow' },
+  )
+})
+
+test('inheritance holds at depth, and is not a way around a self-narrowing', async () => {
+  // No declaration: the user left the session at its directory, and the only
+  // thing that will keep a child inside `inner` is the inherited root.
+  const { captured } = harness({ config: { mode: 'deny' } })
+  await captured.tool.execute({ action: 'focus', paths: ['inner'] }, { agent: agent() })
+
+  const child = childOf('session-1')
+  const grandchild = childOf('child-1', 'grand-1')
+  // The child's own scope is resolved by its first call, which is what puts its
+  // root on the record for the grandchild to inherit.
+  for (const descendant of [child, grandchild]) {
+    assert.equal(
+      (await dispatch(captured, { name: 'read', args: { file_path: 'inner/index.ts' }, agent: descendant })).kind,
+      'allow',
+      `${descendant.session.id} is inside the inherited facet`,
+    )
+    assert.equal(
+      (await dispatch(captured, { name: 'read', args: { file_path: 'index.ts' }, agent: descendant })).kind,
+      'deny',
+      `${descendant.session.id} cannot delegate its way back out of the narrowing`,
+    )
+  }
+})
+
+test('a declaration for the child itself stands over what it would inherit', async () => {
+  const { captured } = harness({
+    config: { mode: 'ask', scopes: { 'session-1': { focus: 'inner' }, 'child-1': { focus: '.' } } },
+  })
+  assert.deepEqual(
+    await dispatch(captured, { name: 'read', args: { file_path: 'inner/index.ts' }, agent: agent() }),
+    { kind: 'allow' },
+  )
+
+  // The user is the authority on this session too: a declaration made for the
+  // child is a statement about the child, and inheritance only answers the case
+  // where they made none.
+  assert.deepEqual(
+    await dispatch(captured, { name: 'read', args: { file_path: 'index.ts' }, agent: childOf('session-1') }),
+    { kind: 'allow' },
+  )
+})
+
 test('a standing grant and a session grant both open the scope', async () => {
   const standing = harness({ extraRoots: ['../../shared'] })
   assert.deepEqual(

test/policy.test.js

@@ -187,3 +187,61 @@ test('junk in a declaration is ignored rather than thrown on', () => {
   assert.deepEqual(policy.scopeFor(agentAt('/w', 's1')).extras, ['/w/ok'])
   assert.equal(policy.scopeFor(agentAt('/w', 's2')).root, '/w')
 })
+
+// ── delegated sessions ───────────────────────────────────────────────────────
+//
+// A session spawned or forked from this one has no declaration of its own, and
+// the user's declaration is keyed by session id. What stops it starting wider
+// than its parent is the parent's own resolved root, recorded as the parent
+// resolves a scope — which it does for every model request and every tool call,
+// so the record is always there before it can spawn anything.
+
+/** An agent whose header carries the lineage the harness writes for a child. */
+const spawned = (id, parentSession, cwd = '/w') => ({
+  session: { id, header: { cwd, parentSession } },
+})
+
+test('a session spawned from a scoped one inherits its root, at any depth', () => {
+  const policy = createFacetPolicy({ mode: 'deny', scopes: { s1: { focus: 'src/room' } } })
+  assert.equal(policy.scopeFor(agentAt('/w', 's1')).root, '/w/src/room')
+
+  const child = spawned('c1', 's1')
+  assert.equal(policy.scopeFor(child).root, '/w/src/room')
+  // Relative paths still resolve from the child's own directory, as for anyone.
+  assert.equal(policy.scopeFor(child).cwd, '/w')
+  assert.equal(policy.scopeFor(spawned('g1', 'c1')).root, '/w/src/room')
+})
+
+test('a child is never wider than its parent is now, narrowing included', () => {
+  const policy = createFacetPolicy({ mode: 'deny' })
+  policy.narrowTo('s1', '/w/src/room')
+
+  // The narrowing is the agent's own decision; spawning a child is not a way to
+  // undo it, because the root the child inherits already includes it.
+  assert.equal(policy.scopeFor(agentAt('/w', 's1')).root, '/w/src/room')
+  assert.equal(policy.scopeFor(spawned('c1', 's1')).root, '/w/src/room')
+})
+
+test('a declaration for the child itself stands over what it would inherit', () => {
+  const policy = createFacetPolicy({ mode: 'deny', scopes: { s1: { focus: 'src/room' }, c1: { focus: '.' } } })
+  policy.scopeFor(agentAt('/w', 's1'))
+
+  // Inheritance answers the case where the user made no statement about this
+  // session; a statement they did make is the more specific one and stands.
+  assert.equal(policy.scopeFor(spawned('c1', 's1')).root, '/w')
+})
+
+test('a root is kept while a session that inherited it is still alive', () => {
+  const policy = createFacetPolicy({ mode: 'deny', scopes: { s1: { focus: 'src/room' } } })
+  const child = spawned('c1', 's1')
+  policy.scopeFor(agentAt('/w', 's1'))
+  policy.scopeFor(child)
+
+  // Disposing the parent must not quietly widen the child that is still running.
+  policy.forget('s1')
+  assert.equal(policy.scopeFor(child).root, '/w/src/room')
+
+  // With nothing left to inherit it, the record goes too.
+  policy.forget('c1')
+  assert.equal(policy.scopeFor(agentAt('/w', 's1')).root, '/w/src/room')
+})