diff --git a/app/changelog.json b/app/changelog.json
index 31b33e0..f85c34f 100644
--- a/app/changelog.json
+++ b/app/changelog.json
@@ -1,4 +1,11 @@
 [
+  {
+    "id": "2026-09-04-share-my-node-name",
+    "date": "2026-09-04",
+    "where": "app",
+    "title": "Share my node name, off unless you turn it on",
+    "body": "A new setting shares your companion's name and key with nodes in direct range, each auto-discover cycle while a companion is your target. Off, the app never transmits who you are."
+  },
   {
     "id": "2026-08-29-theme-follows-your-device",
     "date": "2026-08-29",
diff --git a/app/src/__tests__/announce.test.js b/app/src/__tests__/announce.test.js
new file mode 100644
index 0000000..c6a4706
--- /dev/null
+++ b/app/src/__tests__/announce.test.js
@@ -0,0 +1,27 @@
+import { describe, it, expect } from 'vitest'
+import { buildSelfAdvertFrame, announceThisCycle } from '../announce.js'
+
+// The frame is CMD_SEND_SELF_ADVERT (7) with the route byte at 0, which the
+// firmware reads as zero-hop (examples/companion_radio/MyMesh.cpp:1258, "1 =
+// flood, 0 = zero hop"). A 1 there floods the mesh, so the byte is the test.
+describe('buildSelfAdvertFrame', () => {
+  it('asks the companion for one zero-hop advert, never a flood', () => {
+    expect([...buildSelfAdvertFrame()]).toEqual([7, 0])
+  })
+})
+
+// The advert rides the auto-ping cycle, and only while a selected target is a
+// companion: that is the node that has to hear us before it can answer. With
+// the setting off, or nothing selected that needs it, no cycle carries one.
+describe('announceThisCycle', () => {
+  it('is true only with the setting on, a companion connected, and a companion target', () => {
+    expect(announceThisCycle({ shareName: true, connected: true, companionTargets: 1 })).toBe(true)
+    expect(announceThisCycle({ shareName: false, connected: true, companionTargets: 1 })).toBe(false)
+    expect(announceThisCycle({ shareName: true, connected: false, companionTargets: 1 })).toBe(false)
+    expect(announceThisCycle({ shareName: true, connected: true, companionTargets: 0 })).toBe(false)
+  })
+  // Off by default means a missing or malformed value must read as off.
+  it('treats anything but an explicit true as off', () => {
+    for (const v of [undefined, null, 1, '1', 'true']) expect(announceThisCycle({ shareName: v, connected: true, companionTargets: 2 }), String(v)).toBe(false)
+  })
+})
diff --git a/app/src/__tests__/feed.test.js b/app/src/__tests__/feed.test.js
index ad72eac..235144a 100644
--- a/app/src/__tests__/feed.test.js
+++ b/app/src/__tests__/feed.test.js
@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest'
-import { relTime, senderList, topSenders, targetParts, selectedRepeaterIds, clusterKey, expandSelection, selectionKeyFor, idPrefix, matchesTarget, heardRepeaterIds } from '../feed.js'
+import { relTime, senderList, topSenders, targetParts, selectedRepeaterIds, clusterKey, expandSelection, selectionKeyFor, idPrefix, matchesTarget, heardRepeaterIds, selectedCompanionIds } from '../feed.js'
 
 const rec = (o) => ({ sender_kind: 'channel_name', sender_id: 'Spammer', rx_at: '2026-06-29T10:00:00Z', ...o })
 
@@ -602,3 +602,30 @@ describe('heardRepeaterIds (#479)', () => {
     expect(heardRepeaterIds(rows)).toEqual(['ab12cd'])
   })
 })
+
+// Which selected targets get the self-advert each cycle (#576): the ones a
+// trace-ping cannot reach. A companion answers only a sender it has as a
+// contact, and it adds us when it hears our advert; a repeater needs none of
+// that, so it stays with the trace-ping. Defined as the selection minus the
+// repeater reading, so the two never disagree about one node.
+describe('selectedCompanionIds', () => {
+  const rec = (o) => ({ rx_at: '2026-06-29T10:00:00Z', sender_kind: 'advert_pubkey', ...o })
+  it('returns the selected ids whose node does not behave as a repeater', () => {
+    const rows = [rec({ sender_id: 'aa', sender_role: 'ChatNode' }), rec({ sender_id: 'bb', sender_role: 'Repeater' })]
+    expect(selectedCompanionIds(rows, new Set(['aa', 'bb']))).toEqual(['aa'])
+  })
+  it('leaves out a node only ever heard relaying, and one that answered a trace', () => {
+    const rows = [rec({ sender_id: 'cc', sender_kind: 'relay', sender_role: null }), rec({ sender_id: 'dd', sender_kind: 'trace_reply', sender_role: null })]
+    expect(selectedCompanionIds(rows, new Set(['cc', 'dd']))).toEqual([])
+  })
+  it('is empty with nothing selected, or with a selection nothing was heard from', () => {
+    const rows = [rec({ sender_id: 'aa', sender_role: 'ChatNode' })]
+    expect(selectedCompanionIds(rows, new Set())).toEqual([])
+    expect(selectedCompanionIds(rows, null)).toEqual([])
+    expect(selectedCompanionIds(rows, new Set(['zz']))).toEqual([])
+  })
+  it('lists each node once, however many receptions it has', () => {
+    const rows = [rec({ sender_id: 'AA', sender_role: 'ChatNode' }), rec({ sender_id: 'aa', sender_role: 'ChatNode', rx_at: '2026-06-29T10:01:00Z' })]
+    expect(selectedCompanionIds(rows, new Set(['aa']))).toEqual(['aa'])
+  })
+})
diff --git a/app/src/__tests__/settings.test.js b/app/src/__tests__/settings.test.js
index 7706683..f428f34 100644
--- a/app/src/__tests__/settings.test.js
+++ b/app/src/__tests__/settings.test.js
@@ -1,5 +1,5 @@
 import { describe, it, expect, afterEach, vi } from 'vitest'
-import { isSettingsActive, initialSettingsTab, loadAttenuator, loadSoundMode, loadViewIndex, loadChangelogSeen, saveChangelogSeen, loadLegacyChangelogAck, loadThemePref } from '../settings.js'
+import { isSettingsActive, initialSettingsTab, loadAttenuator, loadSoundMode, loadViewIndex, loadChangelogSeen, saveChangelogSeen, loadLegacyChangelogAck, loadThemePref, loadShareName } from '../settings.js'
 
 // A storage stub whose getItem throws, standing in for the contexts where
 // localStorage access raises SecurityError (Safari with cookies blocked, a
@@ -173,3 +173,34 @@ describe('changelog acknowledgement (#284, #422)', () => {
     expect(() => saveChangelogSeen('2026-08-22-b')).not.toThrow()
   })
 })
+
+// The settings dot says "something behind this button is not at its default".
+// Sharing the node name is exactly that, and it is the one setting that
+// transmits, so it must reach the dot (#576).
+describe('isSettingsActive lights for Share my node name', () => {
+  it('is true with the name shared and everything else at default', () => {
+    expect(isSettingsActive({ attenuatorDb: 0, unseenChangelog: false, shareName: true })).toBe(true)
+    expect(isSettingsActive({ attenuatorDb: 0, unseenChangelog: false, shareName: false })).toBe(false)
+  })
+})
+
+// Share my node name (#576): the first setting that puts the hunter's own
+// identity on air, so it is off unless the stored value says on, exactly.
+describe('loadShareName', () => {
+  it('is on only for the stored on-value', () => {
+    vi.stubGlobal('localStorage', storageWith({ 'core-hunter-share-name': '1' }))
+    expect(loadShareName()).toBe(true)
+  })
+  it('is off for a missing or corrupt value', () => {
+    vi.stubGlobal('localStorage', storageWith({}))
+    expect(loadShareName()).toBe(false)
+    for (const v of ['0', 'true', 'yes', 'on']) {
+      vi.stubGlobal('localStorage', storageWith({ 'core-hunter-share-name': v }))
+      expect(loadShareName(), v).toBe(false)
+    }
+  })
+  it('is off when storage throws', () => {
+    vi.stubGlobal('localStorage', throwingStorage())
+    expect(loadShareName()).toBe(false)
+  })
+})
diff --git a/app/src/announce.js b/app/src/announce.js
new file mode 100644
index 0000000..23307a1
--- /dev/null
+++ b/app/src/announce.js
@@ -0,0 +1,29 @@
+// Share my node name (#576): the one frame that puts the hunter's own identity
+// on air. The companion sends its self-advert: its public key and name, plus a
+// position only if its owner set the location policy in the MeshCore app; this
+// module adds nothing to it. Off by default, and it rides the auto-ping cycle
+// only while a selected target is a companion, the node that has to hear us.
+//
+// Why it exists: MeshCore firmware answers a request only from a sender it can
+// look up in its contact list (src/Mesh.cpp:150-156, the shared secret comes
+// from the contact), and a node adds us to that list when it hears our advert
+// (src/helpers/BaseChatMesh.cpp:151-176). Without it, #553's telemetry request
+// reaches a companion that cannot decrypt it.
+
+// examples/companion_radio/MyMesh.cpp:1250-1268. Byte 1 selects the route:
+// 1 = flood, 0 (or absent) = zero hop. Always 0 here: the advert is for the
+// nodes that can hear us directly, which are the ones we can hunt.
+export const CMD_SEND_SELF_ADVERT = 7
+export const ADVERT_ZERO_HOP = 0
+
+export function buildSelfAdvertFrame() {
+  return Uint8Array.from([CMD_SEND_SELF_ADVERT, ADVERT_ZERO_HOP])
+}
+
+// announceThisCycle: does this auto-ping cycle carry the advert? Only with the
+// setting explicitly on, a companion to send it through, and at least one
+// selected target that needs it (selectedCompanionIds). Anything but an exact
+// true is off, since off is the default this setting protects.
+export function announceThisCycle({ shareName, connected, companionTargets } = {}) {
+  return shareName === true && connected === true && (Number(companionTargets) || 0) > 0
+}
diff --git a/app/src/app.js b/app/src/app.js
index 969edd0..1a7f88e 100644
--- a/app/src/app.js
+++ b/app/src/app.js
@@ -30,7 +30,8 @@ import { createHuntMap } from './huntmap.js'
 import { VIEW_STATES, VIEW_LABELS, nextViewIndex, viewKey } from './maplayers.js'
 import { makeFilter, isFilterActive, DEFAULT_FILTER, FILTER_PACKET_TYPES, SENDER_ID_CLASSES } from './filters.js'
 import { connectButton, connectFailureMessage } from './connectstate.js'
-import { isSettingsActive, initialSettingsTab, loadAttenuator, loadSoundMode, loadViewIndex, loadChangelogSeen, saveChangelogSeen, loadLegacyChangelogAck, loadThemePref } from './settings.js'
+import { isSettingsActive, initialSettingsTab, loadAttenuator, loadSoundMode, loadViewIndex, loadChangelogSeen, saveChangelogSeen, loadLegacyChangelogAck, loadThemePref, loadShareName } from './settings.js'
+import { buildSelfAdvertFrame, announceThisCycle } from './announce.js'
 import { THEME_PREFS, resolveTheme } from './theme.js'
 import { whereLabel, hasUnseenEntries, unseenEntryCount, migratedSeenId } from './changelog.js'
 import { sinceLabel } from './elapsed.js'
@@ -39,7 +40,7 @@ import { createReceptionLog } from './receptionlog.js'
 import { createTargetList } from './targetlist.js'
 import { resolveName, cachedName, resolvableKey } from './names.js'
 import { buildDiscoverFrame, buildTracePathFrame } from './discover.js'
-import { selectedRepeaterIds, heardRepeaterIds, senderList, expandSelection, idPrefix, selectionKeyFor } from './feed.js'
+import { selectedRepeaterIds, selectedCompanionIds, heardRepeaterIds, senderList, expandSelection, idPrefix, selectionKeyFor } from './feed.js'
 import { shouldAutoFire, staggerTargets } from './autoping.js'
 import { nextSweepBatch, noteAsk } from './sweep.js'
 import { createWakeLock } from './wakelock.js'
@@ -81,6 +82,15 @@ function saveAttenuator(db) {
   try { localStorage.setItem('core-hunter-attenuator', String(db)) } catch (_) {}
 }
 
+// Share my node name (#576). Stored as '1' or removed, so loadShareName's
+// exact-match read has one on-value and everything else is off.
+function saveShareName(on) {
+  try {
+    if (on) localStorage.setItem('core-hunter-share-name', '1')
+    else localStorage.removeItem('core-hunter-share-name')
+  } catch (_) {}
+}
+
 // Sound mode (#145): off / rxtx / full, cycled by the sound FAB. Persisted
 // like the attenuator; loader lives in settings.js (guarded + unit-tested, #338).
 function saveSoundMode(mode) {
@@ -165,6 +175,8 @@ const state = {
   published: new Set(),
   ignore: loadIgnore(),
   attenuatorDb: loadAttenuator(),
+  // Share my node name (#576): off by default, the hunter's own decision.
+  shareName: loadShareName(),
   soundMode: loadSoundMode(),
   themePref: loadThemePref(),
   // Unread release notes (#421). Lives on state so the settings button's dot
@@ -1033,6 +1045,11 @@ function autoPingTick() {
   sendDiscover()
   pulseDiscoverBtn()
   sound.txBlip('discover')   // audio twin of the FAB pulse (#145)
+  // With Share my node name on, a cycle that has a companion as target also
+  // carries our advert (#576): that is the node that has to hear us before it
+  // can answer, and one advert at switch-on could be sent while it is out of
+  // range. Zero-hop, so it costs the mesh nothing beyond this one airtime.
+  if (announceThisCycle({ shareName: state.shareName, connected: state.connected, companionTargets: selectedCompanionTargets().length })) sendSelfAdvert()
   // Each staggered trace-ping is also a real transmission — pulse the FAB and
   // sound the cue for it too, but only if the ping actually succeeds (#254).
   // The tx cue follows the same rule as the pulse: it must mean "a frame went
@@ -1091,6 +1108,23 @@ function toggleAutoPing() {
   updateDiscoverBtnVisual()
 }
 
+// The selected targets a trace-ping cannot reach (#576): companions, which
+// answer only a sender they have as a contact.
+function selectedCompanionTargets() {
+  const selected = selectedSet()
+  if (!selected) return []
+  return selectedCompanionIds(state.lastRows, selected)
+}
+
+// sendSelfAdvert asks the companion for one zero-hop advert. A real frame
+// going out, so it gets the FAB pulse and the tx cue like every other one.
+function sendSelfAdvert() {
+  if (!state.connected || !state.transport) return
+  state.transport.send(buildSelfAdvertFrame()).catch(() => {})
+  pulseDiscoverBtn()
+  sound.txBlip('discover')
+}
+
 // ---------------------------------------------------------------------------
 // Connect / disconnect
 // ---------------------------------------------------------------------------
@@ -1638,6 +1672,14 @@ function buildSettingsSheet() {
           </select>
         </label>
       </div>
+      <div class="ss-radio-section">
+        <h3>Identity</h3>
+        <label class="ss-check-row" id="ss-row-share-name">
+          <input type="checkbox" id="ss-share-name" />
+          <span>Share my node name</span>
+        </label>
+        <p class="ss-hint">Shares your companion's name and key with nodes in direct range, once per auto-discover cycle while a companion is your target. Off: the app never transmits who you are.</p>
+      </div>
       <div class="ss-theme-row">
         <span>Theme</span>
         <div id="ss-theme" class="ss-seg" role="group" aria-label="Theme">
@@ -1738,6 +1780,19 @@ function buildSettingsSheet() {
   })
   refreshConnState()
 
+  // Share my node name (#576): a checkbox, saved on change, and the row and
+  // the settings dot both say when it is on.
+  const share = el('ss-share-name')
+  share.checked = state.shareName
+  const syncShareRow = () => el('ss-row-share-name').classList.toggle('active', state.shareName)
+  syncShareRow()
+  share.addEventListener('change', () => {
+    state.shareName = share.checked
+    saveShareName(state.shareName)
+    syncShareRow()
+    refreshSettingsIndicator()
+  })
+
   const atten = el('ss-atten')
   atten.value = String(state.attenuatorDb)
   const syncAttenRow = () => el('ss-row-atten').classList.toggle('active', (Number(atten.value) || 0) !== 0)
diff --git a/app/src/feed.js b/app/src/feed.js
index 76f6d3f..77baa40 100644
--- a/app/src/feed.js
+++ b/app/src/feed.js
@@ -251,6 +251,25 @@ export function selectedRepeaterIds(records, selectedIds) {
   return repeaterIds(records, (id) => selectedIds.has(id))
 }
 
+// selectedCompanionIds is the other half of the selection (#576): the targets
+// a trace-ping cannot reach. A companion answers only a sender it has as a
+// contact, and it adds us when it hears our advert, so these are the nodes the
+// self-advert is for each cycle. Defined as the selection minus the repeater
+// reading, so the two readings never disagree about one node; a room server or
+// a sensor lands here too, which is right, since neither forwards a trace.
+export function selectedCompanionIds(records, selectedIds) {
+  if (!selectedIds || selectedIds.size === 0) return []
+  const repeaters = new Set(selectedRepeaterIds(records, selectedIds).map((id) => id.slice(0, 2)))
+  const out = []
+  for (const r of records || []) {
+    if (r.sender_id == null) continue
+    const id = String(r.sender_id).toLowerCase()
+    if (!selectedIds.has(id) || out.includes(id) || repeaters.has(id.slice(0, 2))) continue
+    out.push(id)
+  }
+  return out
+}
+
 // heardRepeaterIds is the same reading over everything heard rather than over a
 // selection: the nodes worth trace-pinging when no target is chosen (#479). Same
 // per-frame collapse, so the sweep never spends two transmissions on one frame.
diff --git a/app/src/settings.js b/app/src/settings.js
index 48ba000..aba4f72 100644
--- a/app/src/settings.js
+++ b/app/src/settings.js
@@ -45,6 +45,13 @@ export function loadThemePref() {
   return THEME_PREFS.includes(v) ? v : 'system'
 }
 
+// Share my node name (#576): the first setting that puts the hunter's own
+// identity on air. Off unless the stored value says on, exactly: a missing or
+// malformed slot must never read as "share".
+export function loadShareName() {
+  return readStored('core-hunter-share-name') === '1'
+}
+
 // Index into VIEW_STATES for the persisted view (#258). No/corrupt stored
 // value falls back to both/2D — the app's cold default before that merge
 // (huntmap.js's own mode/mode3D defaults), not index 0.
@@ -86,9 +93,12 @@ export function loadLegacyChangelogAck() {
 // button reads as noise, and the two mean the same thing to the person looking
 // at it — there is something behind this button you have not dealt with. What
 // it is, is one tap away, and the tab carries its own dot to say which.
-export function isSettingsActive({ attenuatorDb, unseenChangelog } = {}) {
+export function isSettingsActive({ attenuatorDb, unseenChangelog, shareName } = {}) {
   if (attenuatorDb) return true
   if (unseenChangelog) return true
+  // Sharing the node name is a non-default that transmits (#576), so it is
+  // exactly what the dot is for.
+  if (shareName === true) return true
   return false
 }
 
diff --git a/app/src/styles/app.css b/app/src/styles/app.css
index 729c654..6116a91 100644
--- a/app/src/styles/app.css
+++ b/app/src/styles/app.css
@@ -398,6 +398,11 @@ html, body { margin: 0; height: 100%; background: var(--ch-bg); color: var(--ch-
 .ss-acc-msg.ok { color: var(--ch-sig-cool); }
 .ss-radio-section { margin-top: 16px; }
 .ss-radio-row { display: flex; align-items: center; gap: 8px; margin-top: 8px; font-size: 14px; color: var(--ch-text); }
+/* A checkbox row in Settings (#576): the list-row shape, checkbox first, and
+   the label in accent while the setting is on, like the select rows. */
+.ss-check-row { display: flex; align-items: center; gap: 8px; margin-top: 8px; font-size: 14px; color: var(--ch-text); }
+.ss-check-row.active > span { color: var(--ch-accent); }
+.ss-hint { margin: 4px 0 0; font-size: 12px; line-height: 1.4; color: var(--ch-muted); }
 .ss-radio-row select { padding: 4px 8px; border-radius: 6px; border: 1px solid var(--ch-muted);
   background: transparent; color: var(--ch-text); font-size: 14px; }
 .ss-version-row { display: flex; align-items: center; gap: 8px; }
diff --git a/web/changelog.json b/web/changelog.json
index 31b33e0..f85c34f 100644
--- a/web/changelog.json
+++ b/web/changelog.json
@@ -1,4 +1,11 @@
 [
+  {
+    "id": "2026-09-04-share-my-node-name",
+    "date": "2026-09-04",
+    "where": "app",
+    "title": "Share my node name, off unless you turn it on",
+    "body": "A new setting shares your companion's name and key with nodes in direct range, each auto-discover cycle while a companion is your target. Off, the app never transmits who you are."
+  },
   {
     "id": "2026-08-29-theme-follows-your-device",
     "date": "2026-08-29",