diff --git a/server/__tests__/lane-features.test.js b/server/__tests__/lane-features.test.js
new file mode 100644
index 0000000..1b610fd
--- /dev/null
+++ b/server/__tests__/lane-features.test.js
@@ -0,0 +1,133 @@
+/**
+ * @file Tests for server/lib/lane-features.js: slug canonicalization,
+ * activate/archive semantics, and read access to a lane's feature history.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+const os = require("node:os");
+const path = require("node:path");
+const fs = require("node:fs");
+
+const SUITE_ROOT = fs.mkdtempSync(path.join(os.tmpdir(), "ccam-lane-features-"));
+process.env.DASHBOARD_DB_PATH = path.join(SUITE_ROOT, "dashboard.db");
+process.env.LANES_ROOT = path.join(SUITE_ROOT, "lanes");
+
+const { describe, it, after } = require("node:test");
+const assert = require("node:assert/strict");
+
+const lanesLib = require("../lib/lanes");
+const features = require("../lib/lane-features");
+
+after(() => fs.rmSync(SUITE_ROOT, { recursive: true, force: true }));
+
+let laneSeq = 0;
+function makeLane() {
+  laneSeq += 1;
+  const cwd = path.join(SUITE_ROOT, `lane-cwd-${laneSeq}`);
+  fs.mkdirSync(cwd, { recursive: true });
+  return lanesLib.createLane({ title: `lane ${laneSeq}`, cwd, kind: "managed" });
+}
+
+describe("canonicalizeSlug", () => {
+  it("drops a leading feat/ prefix", () => {
+    assert.equal(features.canonicalizeSlug("feat/my-thing"), "my-thing");
+  });
+
+  it("turns slashes and spaces into a single flat dash-separated segment", () => {
+    assert.equal(features.canonicalizeSlug("feat/some thing/ nested"), "some-thing-nested");
+  });
+
+  it("keeps dots, underscores, and case as-is (unlike worktree.js:slugify)", () => {
+    assert.equal(features.canonicalizeSlug("My_Feature.v2"), "My_Feature.v2");
+  });
+
+  it("collapses repeated separators and trims leading/trailing dashes", () => {
+    assert.equal(features.canonicalizeSlug("feat//too  many///slashes/"), "too-many-slashes");
+  });
+
+  it("refuses an empty result", () => {
+    assert.throws(
+      () => features.canonicalizeSlug("feat/"),
+      (err) => err.code === "EBADSLUG"
+    );
+    assert.throws(
+      () => features.canonicalizeSlug("   "),
+      (err) => err.code === "EBADSLUG"
+    );
+  });
+});
+
+describe("activateFeature / archiveActiveFeature", () => {
+  it("activating a brand-new slug creates a live (unarchived) feature row and points the lane at it", () => {
+    const lane = makeLane();
+    const { lane: updated, feature } = features.activateFeature(lane.id, "feat/one");
+    assert.equal(feature.slug, "one");
+    assert.equal(feature.archived_at, null);
+    assert.equal(updated.active_feature_id, feature.id);
+  });
+
+  it("activating a second slug archives the first with its final stage intact", () => {
+    const lane = makeLane();
+    features.activateFeature(lane.id, "one");
+    lanesLib.setStage(lane.id, { stage: "review", evidence: "looks good" });
+
+    const { feature: second } = features.activateFeature(lane.id, "two");
+    assert.equal(second.slug, "two");
+    assert.equal(second.archived_at, null);
+
+    const first = features.getFeature(lane.id, "one");
+    assert.notEqual(first.archived_at, null);
+    assert.equal(first.stage, "review");
+    assert.deepEqual(first.stages.review.evidence, "looks good");
+  });
+
+  it("re-activating an archived slug restores its saved stage onto the live lane row", () => {
+    const lane = makeLane();
+    features.activateFeature(lane.id, "one");
+    lanesLib.setStage(lane.id, { stage: "implement" });
+    features.activateFeature(lane.id, "two"); // archives "one" at stage=implement
+
+    const { lane: reactivated } = features.activateFeature(lane.id, "one");
+    assert.equal(reactivated.stage, "implement");
+    assert.equal(features.getFeature(lane.id, "one").archived_at, null);
+    assert.notEqual(features.getFeature(lane.id, "two").archived_at, null);
+  });
+
+  it("re-activating the CURRENTLY active slug is a no-op, not a self-archive", () => {
+    const lane = makeLane();
+    features.activateFeature(lane.id, "one");
+    lanesLib.setStage(lane.id, { stage: "review" });
+    const { lane: updated } = features.activateFeature(lane.id, "one");
+    assert.equal(updated.stage, "review");
+    assert.equal(features.getFeature(lane.id, "one").archived_at, null);
+  });
+
+  it("archiveActiveFeature returns null and touches nothing when no feature is active", () => {
+    const lane = makeLane();
+    assert.equal(features.archiveActiveFeature(lane.id), null);
+  });
+
+  it("echoes back the canonicalized slug, not the caller's raw input", () => {
+    const lane = makeLane();
+    const { feature } = features.activateFeature(lane.id, "feat/Weird Input/");
+    assert.equal(feature.slug, "Weird-Input");
+  });
+});
+
+describe("listFeatures / getFeature", () => {
+  it("lists every feature for a lane, most recently touched first", () => {
+    const lane = makeLane();
+    features.activateFeature(lane.id, "one");
+    features.activateFeature(lane.id, "two");
+    const list = features.listFeatures(lane.id);
+    assert.deepEqual(
+      list.map((f) => f.slug),
+      ["two", "one"]
+    );
+  });
+
+  it("getFeature returns null for an unknown slug", () => {
+    const lane = makeLane();
+    assert.equal(features.getFeature(lane.id, "never-activated"), null);
+  });
+});
diff --git a/server/db.js b/server/db.js
index 7f67d1b..a209222 100644
--- a/server/db.js
+++ b/server/db.js
@@ -432,6 +432,31 @@ db.exec(`
     updated_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now'))
   );
 
+  CREATE TABLE IF NOT EXISTS lane_features (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    lane_id INTEGER NOT NULL,
+    slug TEXT NOT NULL,
+    title TEXT NOT NULL DEFAULT '',
+    branch TEXT,
+    pipeline TEXT NOT NULL DEFAULT 'default',
+    stage TEXT NOT NULL DEFAULT 'idle',
+    stage_since TEXT,
+    status TEXT NOT NULL DEFAULT 'idle',
+    gate_decision TEXT,
+    ci_status TEXT,
+    qc_dev TEXT,
+    stages TEXT NOT NULL DEFAULT '{}',
+    links TEXT NOT NULL DEFAULT '{}',
+    notes TEXT,
+    archived_at TEXT,
+    created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now')),
+    updated_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now')),
+    UNIQUE (lane_id, slug),
+    FOREIGN KEY (lane_id) REFERENCES lanes(id) ON DELETE CASCADE
+  );
+
+  CREATE INDEX IF NOT EXISTS idx_lane_features_lane ON lane_features(lane_id);
+
   CREATE INDEX IF NOT EXISTS idx_lanes_session ON lanes(session_id);
 `);
 
@@ -519,6 +544,22 @@ db.prepare(
   "CREATE UNIQUE INDEX IF NOT EXISTS idx_lanes_slot ON lanes(slot) WHERE slot IS NOT NULL"
 ).run();
 
+// Migrate: per-feature state (B). `active_feature_id` points at the
+// lane_features row currently "live" (unarchived) for this lane — null for a
+// lane that has never called `ccam feature activate`, which is why this
+// column is nullable and every downstream reader of a lane row is unaffected
+// by its addition. ON DELETE SET NULL, not CASCADE: deleting the ACTIVE
+// feature row (which normally only happens via cascade when the LANE itself
+// is deleted, at which point this column is moot anyway) must never leave a
+// dangling id on a lane row that still exists.
+try {
+  db.prepare("SELECT active_feature_id FROM lanes LIMIT 1").get();
+} catch {
+  db.prepare(
+    "ALTER TABLE lanes ADD COLUMN active_feature_id INTEGER REFERENCES lane_features(id) ON DELETE SET NULL"
+  ).run();
+}
+
 // Migrate: link agent rows to a workflow run. Workflow inner-agents are already
 // ingested as subagents (same subagents/ dir); these columns add the grouping +
 // phase that the run journal provides. Additive, safe on existing DBs.
diff --git a/server/lib/lane-features.js b/server/lib/lane-features.js
new file mode 100644
index 0000000..8d77b1a
--- /dev/null
+++ b/server/lib/lane-features.js
@@ -0,0 +1,199 @@
+/**
+ * @file Per-feature state and archive (B). A lane's `stage`/`status`/etc. is
+ * the LIVE view of whichever feature it's currently working on; this module
+ * lets a lane carry many features across its lifetime by snapshotting the
+ * live row into `lane_features` whenever the lane switches (or is cleared),
+ * and restoring a feature's saved state when it's switched back to.
+ *
+ * The `lanes` row itself never changes shape — every existing reader of a
+ * lane keeps working unmodified. Only `lanes.active_feature_id` (nullable)
+ * is new there, pointing at the currently-live (unarchived) feature row, or
+ * null for a lane that has never called `activate`.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+const { db } = require("../db");
+const lanesLib = require("./lanes");
+
+const nowIso = () => new Date().toISOString();
+
+/**
+ * Canonicalize a feature slug: drop a leading `feat/`, turn `/` and
+ * whitespace runs into a single `-`, keep only `[A-Za-z0-9._-]`, collapse
+ * repeated `-`, trim leading/trailing `-`. Deliberately does NOT lowercase —
+ * a separate function from `worktree.js:slugify` (that one exists for git
+ * branch names and lowercases everything), never reused here, never let the
+ * two drift onto the same rule by accident.
+ *
+ * @param {string} input
+ * @returns {string}
+ * @throws {Error} EBADSLUG when the result is empty.
+ */
+function canonicalizeSlug(input) {
+  const withoutPrefix = String(input || "").replace(/^feat\//, "");
+  const result = withoutPrefix
+    .replace(/[\s/]+/g, "-")
+    .replace(/[^A-Za-z0-9._-]/g, "")
+    .replace(/-+/g, "-")
+    .replace(/^-+|-+$/g, "");
+  if (!result) {
+    throw Object.assign(new Error("slug is empty"), { code: "EBADSLUG" });
+  }
+  return result;
+}
+
+function hydrate(row) {
+  if (!row) return null;
+  let stages = {};
+  let links = {};
+  try {
+    stages = JSON.parse(row.stages || "{}");
+  } catch {
+    /* corrupt blob -> empty */
+  }
+  try {
+    links = JSON.parse(row.links || "{}");
+  } catch {
+    /* corrupt blob -> empty */
+  }
+  return { ...row, stages, links };
+}
+
+/** Every feature a lane has ever activated, most recently touched first. */
+function listFeatures(laneId) {
+  return db
+    .prepare("SELECT * FROM lane_features WHERE lane_id = ? ORDER BY updated_at DESC, id DESC")
+    .all(laneId)
+    .map(hydrate);
+}
+
+/** One feature by slug, or null. */
+function getFeature(laneId, slug) {
+  return hydrate(
+    db.prepare("SELECT * FROM lane_features WHERE lane_id = ? AND slug = ?").get(laneId, slug)
+  );
+}
+
+function getFeatureById(id) {
+  return hydrate(db.prepare("SELECT * FROM lane_features WHERE id = ?").get(id));
+}
+
+/**
+ * Snapshot a lane's CURRENT live bookkeeping into its active feature row
+ * (if it has one) and mark that row archived. Returns the archived row, or
+ * null when the lane has no active feature — archiving is opt-in, so a lane
+ * that never called `activate` is untouched.
+ *
+ * Does NOT reset the live `lanes` row — that stays the caller's job
+ * (`clearLane` resets after archiving; `activateFeature` overwrites the live
+ * row with the newly-activated feature's saved state instead of resetting).
+ *
+ * @param {number} laneId
+ * @returns {object|null} The archived feature row.
+ */
+function archiveActiveFeature(laneId) {
+  const lane = lanesLib.getLane(laneId);
+  if (!lane || !lane.active_feature_id) return null;
+  const active = getFeatureById(lane.active_feature_id);
+  if (!active) return null;
+
+  db.prepare(
+    `UPDATE lane_features SET
+       title = ?, branch = ?, pipeline = ?, stage = ?, stage_since = ?, status = ?,
+       gate_decision = ?, ci_status = ?, qc_dev = ?, stages = ?, links = ?, notes = ?,
+       archived_at = ?, updated_at = ?
+     WHERE id = ?`
+  ).run(
+    lane.title,
+    lane.branch,
+    lane.pipeline,
+    lane.stage,
+    lane.stage_since,
+    lane.status,
+    lane.gate_decision,
+    lane.ci_status,
+    active.qc_dev, // qc_dev has no equivalent on `lanes` — carried over from the feature row itself, untouched by the live lane
+    JSON.stringify(lane.stages || {}),
+    JSON.stringify(lane.links || {}),
+    lane.notes,
+    nowIso(),
+    nowIso(),
+    active.id
+  );
+  return getFeatureById(active.id);
+}
+
+/**
+ * Activate a feature by slug: archive the currently-active feature (if any,
+ * and if it isn't this same slug), find-or-create the target feature row,
+ * copy ITS saved bookkeeping onto the live `lanes` row (so switching back to
+ * a past feature resumes where it left off — a brand-new slug copies in
+ * fresh defaults), and point `lanes.active_feature_id` at it.
+ *
+ * Re-activating the CURRENTLY active slug is a no-op on the archive step —
+ * the live row already IS that feature's state, so there's nothing to
+ * restore and nothing to archive.
+ *
+ * @param {number} laneId
+ * @param {string} rawSlug - Canonicalized internally; the caller's raw input is never stored.
+ * @param {{title?: string}} [options]
+ * @returns {{lane: object, feature: object}}
+ */
+function activateFeature(laneId, rawSlug, options = {}) {
+  const slug = canonicalizeSlug(rawSlug);
+  const lane = lanesLib.getLane(laneId);
+  if (!lane) throw Object.assign(new Error(`no lane ${laneId}`), { code: "ENOLANE" });
+
+  const current = lane.active_feature_id ? getFeatureById(lane.active_feature_id) : null;
+  if (current && current.slug === slug) {
+    return { lane, feature: current };
+  }
+
+  if (current) archiveActiveFeature(laneId);
+
+  let target = getFeature(laneId, slug);
+  if (!target) {
+    const info = db
+      .prepare(
+        `INSERT INTO lane_features (lane_id, slug, title, branch, pipeline, stage, stage_since, status, stages, links, notes)
+         VALUES (?, ?, ?, ?, ?, 'idle', ?, 'idle', '{}', '{}', NULL)`
+      )
+      .run(laneId, slug, options.title || slug, lane.branch, lane.pipeline, nowIso());
+    target = getFeatureById(info.lastInsertRowid);
+  } else {
+    // Un-archive it — it's about to become the live view again.
+    db.prepare("UPDATE lane_features SET archived_at = NULL, updated_at = ? WHERE id = ?").run(
+      nowIso(),
+      target.id
+    );
+    target = getFeatureById(target.id);
+  }
+
+  db.prepare(
+    `UPDATE lanes SET
+       stage = ?, stage_since = ?, status = ?, gate_decision = ?, ci_status = ?,
+       stages = ?, notes = ?, active_feature_id = ?, updated_at = ?
+     WHERE id = ?`
+  ).run(
+    target.stage,
+    target.stage_since,
+    target.status,
+    target.gate_decision,
+    target.ci_status,
+    JSON.stringify(target.stages || {}),
+    target.notes,
+    target.id,
+    nowIso(),
+    laneId
+  );
+
+  return { lane: lanesLib.getLane(laneId), feature: getFeatureById(target.id) };
+}
+
+module.exports = {
+  canonicalizeSlug,
+  listFeatures,
+  getFeature,
+  activateFeature,
+  archiveActiveFeature,
+};