diff --git a/keel/web/static/css/keel.css b/keel/web/static/css/keel.css
index 7cd0770..a3daee6 100644
--- a/keel/web/static/css/keel.css
+++ b/keel/web/static/css/keel.css
@@ -245,6 +245,48 @@ header .mode {
  * pill is a stray mark, and an unreadable config should cost the badge rather than guess a
  * mode. Same pairing as `#build` in the footer, which is also empty until the same read. */
 header .mode:empty { display: none; }
+
+/* ── the deployment card (#755) ───────────────────────────────────────────────────────────────
+ *
+ * The badge is the `<summary>` of a native disclosure, so the identifying `--db`/`--config` pair
+ * -- which `modeBadge` also writes into a `title`, and `title` is hover-only -- is reachable by
+ * tap on a device that has no pointer.
+ *
+ * The whole disclosure hides when the badge is empty, matching `header .mode:empty`: a config
+ * that could not be read is not a deployment called "unknown", and an empty pill with a
+ * disclosure triangle beside it would be worse than nothing. */
+header #deployment:has(> summary:empty) { display: none; }
+
+header #deployment { position: relative; }
+
+/* The default triangle is removed on BOTH spellings -- `::-webkit-details-marker` for older
+ * WebKit, `list-style` for everything current -- because the badge is a pill and a marker glued
+ * to it reads as a chevron on a button, which is the dropdown this is deliberately not. */
+header #deployment > summary { cursor: pointer; list-style: none; }
+header #deployment > summary::-webkit-details-marker { display: none; }
+
+/* Anchored to the badge and OUT of flow: opening it must not reflow the header, which on a narrow
+ * screen would push the nav around under the reader's finger mid-tap. */
+header #deployment > #deployment-card {
+  position: absolute;
+  right: 0;
+  top: calc(100% + 0.4rem);
+  z-index: 2;
+  min-width: min(22rem, 88vw);
+  background: var(--bg);
+  border: 1px solid var(--control-line);
+  border-radius: 6px;
+  padding: 0.6rem;
+  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.18);
+  text-align: left;
+}
+
+/* The paths are the point of the card and they are long. Wrapping beats a horizontal scrollbar
+ * inside a popover no wider than a phone. */
+header #deployment > #deployment-card .v {
+  overflow-wrap: anywhere;
+  font-size: 0.85em;
+}
 /* The emphasis table `render.js::MODE_CLASS` places: paper is the quiet one (muted, like any
  * label), confirm and live carry the accent, because a deployment that can place orders should
  * sit up in the header. NOT `--good`/`--bad` -- those are `state`'s vocabulary and there is no
diff --git a/keel/web/static/index.html b/keel/web/static/index.html
index 09b3273..eaebd03 100644
--- a/keel/web/static/index.html
+++ b/keel/web/static/index.html
@@ -178,7 +178,7 @@
     (`:empty` in `keel.css`), because an empty pill is a stray mark, and an unreadable config
     should cost the badge rather than guess a mode.
   -->
-<span class="right">
+<div class="right">
     <!--
       THE SESSION CHIP (#704): profile · mode · equity state, on every view.
 
@@ -195,11 +195,30 @@
       Both halves empty in the markup and hidden while empty (`:empty` in `keel.css`), like
       `#mode-badge` and `#build`: a deployment with no readable name is not one called "unknown".
     -->
-    <span id="session-chip">
+    <!--
+      THE DEPLOYMENT CARD (#755): the badge is the SUMMARY of a native disclosure.
+
+      `modeBadge` writes the identifying `--db`/`--config` pair into a `title`, which is a HOVER
+      tooltip -- and there is no hover on a phone, the exact device Phase B is for. So the same
+      facts get a tap-to-reveal path here.
+
+      `<details>` and NOT a button with a handler: it is keyboard-operable, touch-operable and
+      announced with nothing bound, which is what lets the card pass the same no-interactive-node
+      test the chip and the banner answer to (`venueCard` uses the element the same way). Nothing
+      inside it changes anything; switching mode or profile stays a terminal ceremony.
+
+      `#session-chip` and `.right` are DIVs rather than spans because `<details>` is flow content
+      and a `<span>` may only hold phrasing content. Both already set their own `display` in
+      `keel.css`, so the layout is unchanged by the tag.
+    -->
+    <div id="session-chip">
       <span id="session-profile" class="sessionpart"></span>
-      <span id="mode-badge" class="pill mode"></span>
+      <details id="deployment">
+        <summary id="mode-badge" class="pill mode"></summary>
+        <div id="deployment-card"></div>
+      </details>
       <span id="session-equity" class="sessionpart"></span>
-    </span>
+    </div>
   
     <!--
       THE THEME TOGGLE (#597): two states, and the stylesheet is the state machine.
@@ -236,7 +255,7 @@
         <path d="M20.2 13.2A8.2 8.2 0 1 1 10.8 3.8a6.5 6.5 0 0 0 9.4 9.4Z"/>
       </svg>
     </button>
-  </span>
+  </div><!-- .right -->
 </header>
 
 <!--
diff --git a/keel/web/static/js/main.js b/keel/web/static/js/main.js
index fd7b6c3..4c6f04b 100644
--- a/keel/web/static/js/main.js
+++ b/keel/web/static/js/main.js
@@ -44,6 +44,7 @@ import {
   gatesView,
   plansView,
   insightsView,
+  deploymentCard,
   modeBadge,
   paperBanner,
   sessionChip,
@@ -153,6 +154,8 @@ const updateNode = must("update");
 const modeNode = must("mode-badge");
 /** The session chip's profile half (#704) -- the database's own name, filled from the boot read. */
 const sessionProfileNode = must("session-profile");
+//: #755. The badge is the disclosure's summary; this is what the disclosure reveals.
+const deploymentCardNode = must("deployment-card");
 /** The session chip's equity-state half (#704). Genuinely absent on a deployment that has never
  * flipped modes, which is why it is a `Field` and not a bare word. */
 const sessionEquityNode = must("session-equity");
@@ -1537,6 +1540,10 @@ void read("config").then((reading) => {
   // process serves cannot change without a restart, and filling the chip here is what puts it on
   // every view rather than only where a status report happens to load.
   sessionChip(sessionProfileNode, sessionEquityNode, config);
+  // #755: the same boot read, for the same reason -- and the card must be filled even
+  // though it is closed, because a `<details>` opens with no JavaScript involved and
+  // there is no event to fill it on.
+  deploymentCard(deploymentCardNode, config);
   paperBanner(modeBannerNode, config);
   registerWorker(config);
   show(booted, false);
diff --git a/keel/web/static/js/render.js b/keel/web/static/js/render.js
index 233411c..8caf579 100644
--- a/keel/web/static/js/render.js
+++ b/keel/web/static/js/render.js
@@ -3355,6 +3355,57 @@ export function modeBadge(node, config) {
   node.title = (config.db_path || "").concat(" · config ", config.config_path || "");
 }
 
+//: What the card says where a control would be. Static copy, not payload prose: `paperBanner`'s
+//: sentence arrives from Python because that function CHOOSES between sentences on the basis of a
+//: config, which is a judgement. This one is the same words on every deployment, so it is UI copy
+//: in the class of `plansView`'s subtitle, and Rule 2 has nothing to say about it.
+const SWITCHING_NOTE = "Mode and profile switching are terminal ceremonies with a runbook. ".concat(
+  "This console reports the deployment it was pointed at and cannot change it.",
+);
+
+/**
+ * The deployment identity card (#755) -- the `title` tooltip's contents, reachable by touch.
+ *
+ * `modeBadge` writes `--db` and `--config` into a `title`, and `title` is a HOVER tooltip. There
+ * is no hover on a phone, which is the device #648/#656 exist for, so the half of the badge that
+ * actually IDENTIFIES a deployment was unreachable exactly where the terminal is least available.
+ * The mode word alone identifies nothing: two paper deployments both say `paper`, and a live
+ * sandbox and a paper-equities profile can both say `confirm`.
+ *
+ * **It reveals and it does not offer.** The disclosure is `<details>` in the shell, so there is no
+ * handler to bind and no button to build, and this function is held to the same
+ * no-interactive-node test as `sessionChip` and `paperBanner` rather than exempted from it. A
+ * "switch to live" affordance arriving through a door marked accessibility is still the growth
+ * funnel the chip's docstring refuses.
+ *
+ * The origin comes from `window.location`, not the payload -- it is a fact about where this
+ * browser is, and in an installed app there is no address bar to read it from. `timelineView`
+ * takes it from the same place for the same reason.
+ *
+ * Empty when the config could not be read, matching `modeBadge`: an absent answer is not `paper`,
+ * and a card naming a deployment nothing could identify would be inventing one.
+ *
+ * @param {HTMLElement} node
+ * @param {any} config  `/api/config`'s `data`, or `null`.
+ */
+export function deploymentCard(node, config) {
+  const mode = config && typeof config.mode === "string" ? config.mode : "";
+  if (!mode) {
+    node.replaceChildren();
+    return;
+  }
+  node.replaceChildren(
+    gridCard([
+      kv("deployment", config.profile || "\u2014"),
+      kv("mode", mode),
+      kv("config", config.config_path || "\u2014"),
+      kv("database", config.db_path || "\u2014"),
+      kv("origin", window.location.origin),
+    ]),
+    el("p", "muted", SWITCHING_NOTE),
+  );
+}
+
 /**
  * The session chip's two halves, from `/api/config` (#704).
  *
diff --git a/tests/web/test_client_assets.py b/tests/web/test_client_assets.py
index 785e264..6ad85cc 100644
--- a/tests/web/test_client_assets.py
+++ b/tests/web/test_client_assets.py
@@ -898,7 +898,11 @@ def test_the_header_carries_a_theme_toggle_and_a_mode_badge() -> None:
             f"an icon that is not token-coloured or is self-announcing: {icon}"
         )
 
-    assert '<span id="mode-badge" class="pill mode"' in html, "the mode badge is missing"
+    # A `<summary>` since #755, not a `<span>`: the badge is the summary of the deployment card's
+    # native disclosure, which is what gives a touch device a path to the `--db`/`--config` pair
+    # that `modeBadge` also writes into a hover-only `title`. The id and both classes are
+    # unchanged, and they are what `modeBadge` and `header .mode:empty` actually key on.
+    assert '<summary id="mode-badge" class="pill mode"' in html, "the mode badge is missing"
     # Empty in the markup, like #build: filled from the boot config read, hidden until it is.
     assert html.count('id="mode-badge"') == 1
 
@@ -935,6 +939,9 @@ def test_the_theme_choice_is_spelled_where_it_is_stored() -> None:
     # empty forever, which is precisely the failure named below.
     ("sessionChip", "config"),
     ("paperBanner", "config"),
+    # #755's card, registered in the same commit that adds it, for the reason above: it reads
+    # four config keys and a rename on either side would leave it rendering em-dashes forever.
+    ("deploymentCard", "config"),
 )
 
 
@@ -2084,7 +2091,9 @@ def test_neither_the_chip_nor_the_banner_builds_anything_clickable() -> None:
     either. So neither function may create an interactive node or bind a handler.
     """
     source = _source("render.js")
-    for name in ("sessionChip", "paperBanner"):
+    # #755's `deploymentCard` joins them rather than getting an exemption: it is the surface where
+    # a reader looks for the control, which makes it the likeliest place for one to be added.
+    for name in ("sessionChip", "paperBanner", "deploymentCard"):
         body = _function_body(source, name)
         for forbidden in _INTERACTIVE_TOKENS:
             assert forbidden not in body, f"{name} builds something interactive: {forbidden}"
diff --git a/tests/web/test_deployment_card.py b/tests/web/test_deployment_card.py
new file mode 100644
index 0000000..469c50f
--- /dev/null
+++ b/tests/web/test_deployment_card.py
@@ -0,0 +1,112 @@
+"""The deployment identity card: "which deployment is this" without a pointer (#755).
+
+`modeBadge` puts the mode WORD in the badge and the identifying `--db`/`--config` pair in a
+`title` attribute. `title` renders as a hover tooltip, and there is no hover on a touch device --
+so on the exact device Phase B (#648, #656) is built for, the half of the badge that distinguishes
+two paper deployments, or paper from live when both read `confirm`, is unreachable.
+
+**This adds no way to CHANGE anything, and the tests below are mostly about that.** Switching mode
+or profile is a config-file edit plus a typed terminal ceremony; `render.js`'s own chip docstring
+refuses the control and `test_neither_the_chip_nor_the_banner_builds_anything_clickable` pins the
+refusal. A disclosure that reveals read-only facts is not that control, and the tests here hold it
+to the same standard rather than exempting it.
+
+A browser cannot run here, so these are source assertions -- see `test_client_assets`'s docstring
+for the standing argument, and note the same comment-stripping discipline: a scan that a docstring
+can satisfy is a scan that proves nothing.
+"""
+
+from __future__ import annotations
+
+import re
+
+from keel.web import staticfiles
+from tests.web.test_client_assets import _INTERACTIVE_TOKENS, _function_body, _source
+
+_RENDER = _source("render.js")
+_MAIN = (staticfiles.STATIC_ROOT / "js" / "main.js").read_text()
+_INDEX = (staticfiles.STATIC_ROOT / "index.html").read_text()
+_CSS = (staticfiles.STATIC_ROOT / "css" / "keel.css").read_text()
+_CSS_RULES = re.sub(r"/\*.*?\*/", "", _CSS, flags=re.S)
+
+
+def test_the_card_exists_and_is_exported() -> None:
+    assert "export function deploymentCard(" in _RENDER
+
+
+def test_the_shell_actually_calls_it() -> None:
+    """An uncalled renderer still READS the keys it reads, so the config-parity scan passes over
+    one that nothing mounts. #704's lesson, applied on the way in rather than after a review."""
+    assert "deploymentCard" in _MAIN, "render.js exports it and the shell never mounts it"
+    assert _MAIN.count("deploymentCard(") >= 1
+
+
+def test_the_card_names_every_fact_that_identifies_a_deployment() -> None:
+    """The mode word alone does not identify anything: two paper deployments both say `paper`,
+    and a live sandbox and a paper-equities profile can both say `confirm`. The pair that
+    distinguishes them is the point of the card."""
+    body = _function_body(_RENDER, "deploymentCard")
+    for key in ("config.db_path", "config.config_path", "config.mode", "config.profile"):
+        assert key in body, f"the card does not name {key}"
+
+
+def test_the_card_builds_nothing_that_could_change_anything() -> None:
+    """Held to the SAME list as the chip and the banner, deliberately.
+
+    A card that reveals facts is the whole request; a card that grew a "switch to live" affordance
+    would be the growth funnel `sessionChip`'s docstring refuses, arriving through a door marked
+    accessibility.
+    """
+    body = _function_body(_RENDER, "deploymentCard")
+    for forbidden in _INTERACTIVE_TOKENS:
+        assert forbidden not in body, f"deploymentCard builds something interactive: {forbidden}"
+
+
+def test_the_disclosure_is_native_and_needs_no_handler() -> None:
+    """`<details>`/`<summary>` is keyboard-operable, touch-operable and announced, with no
+    listener to bind and no button to build -- which is what lets this pass the test above.
+
+    `venueCard` already uses the same element for the same reason, so this is the established
+    pattern here rather than a new one."""
+    assert 'id="deployment"' in _INDEX
+    assert "<details" in _INDEX, "the card is not a native disclosure"
+    assert "<summary" in _INDEX
+
+
+def test_the_badge_still_owns_the_mode_word_and_keeps_its_tooltip() -> None:
+    """#755 asks for the touch path and says not to remove the pointer one: `title` works for
+    keyboard and desktop and costs nothing to keep."""
+    badge = _function_body(_RENDER, "modeBadge")
+    assert "node.title" in badge, "the hover tooltip was removed rather than supplemented"
+    assert "config.mode" in badge or "config && typeof config.mode" in badge
+
+
+def test_the_card_survives_navigation_because_it_sits_outside_the_view() -> None:
+    """`#view` is replaced wholesale on every route change. The same argument the chip and the
+    banner already answer to."""
+    view_at = _INDEX.index('id="view"')
+    assert _INDEX.index('id="deployment"') < view_at, "the card is inside #view and gets repainted"
+
+
+def test_the_card_says_that_switching_is_not_available_here() -> None:
+    """The one sentence that turns an absence into a statement. Without it the card reads as an
+    unfinished settings panel; with it, the refusal is legible where someone would look for the
+    control."""
+    body = _function_body(_RENDER, "deploymentCard")
+    assert "SWITCHING_NOTE" in body, "the card places no such sentence"
+
+    # And the constant it places actually says it. Asserting the reference alone would pass over
+    # a `SWITCHING_NOTE` that had been emptied or reworded into an invitation -- the same gap
+    # `test_a_click_is_acknowledged_without_claiming_arrival` closes for `markPending`.
+    note = re.search(r"const SWITCHING_NOTE =(.+?);", _RENDER, flags=re.S)
+    assert note, "SWITCHING_NOTE is not defined in render.js"
+    words = note.group(1)
+    assert "terminal" in words and "cannot change" in words, words
+    for invitation in ("upgrade", "Go live", "switch to live", "Open Live"):
+        assert invitation.lower() not in words.lower(), (
+            "the refusal sentence has become an invitation: " + invitation
+        )
+
+
+def test_the_card_is_styled() -> None:
+    assert "#deployment" in _CSS_RULES, "nothing styles the card"