diff --git a/canvas/e2e/chat-separation.spec.ts b/canvas/e2e/chat-separation.spec.ts
index 2492fda84..f5ea831ac 100644
--- a/canvas/e2e/chat-separation.spec.ts
+++ b/canvas/e2e/chat-separation.spec.ts
@@ -8,8 +8,8 @@ import {
   seedChatHistory,
 } from "./fixtures/chat-seed";
 
-const API = process.env.E2E_API_URL ?? "http://localhost:8080";
 const PLATFORM_URL = process.env.E2E_PLATFORM_URL ?? "http://localhost:8080";
+const API = process.env.E2E_API_URL ?? PLATFORM_URL;
 const ADMIN_TOKEN = process.env.E2E_ADMIN_TOKEN ?? process.env.ADMIN_TOKEN;
 
 /** Enter the Org-map view so the Canvas (React Flow graph) mounts. */
@@ -191,6 +191,7 @@ test.describe("Activity API Source Filter", () => {
   test("source=canvas returns only canvas-initiated entries", async ({ request }) => {
     const res = await request.get(
       `${API}/workspaces/${workspaceId}/activity?source=canvas`,
+      { headers: { Authorization: `Bearer ${authToken}` } },
     );
     expect(res.ok()).toBeTruthy();
     const entries = (await res.json()) as Array<{ source_id: unknown }>;
@@ -205,6 +206,7 @@ test.describe("Activity API Source Filter", () => {
   test("source=agent returns only agent-initiated entries", async ({ request }) => {
     const res = await request.get(
       `${API}/workspaces/${workspaceId}/activity?source=agent`,
+      { headers: { Authorization: `Bearer ${authToken}` } },
     );
     expect(res.ok()).toBeTruthy();
     const entries = (await res.json()) as Array<{ source_id: unknown }>;
@@ -219,6 +221,7 @@ test.describe("Activity API Source Filter", () => {
   test("source=invalid returns 400", async ({ request }) => {
     const res = await request.get(
       `${API}/workspaces/${workspaceId}/activity?source=bogus`,
+      { headers: { Authorization: `Bearer ${authToken}` } },
     );
     expect(res.status()).toBe(400);
   });
@@ -226,6 +229,7 @@ test.describe("Activity API Source Filter", () => {
   test("source+type filters combine correctly", async ({ request }) => {
     const res = await request.get(
       `${API}/workspaces/${workspaceId}/activity?type=a2a_receive&source=canvas`,
+      { headers: { Authorization: `Bearer ${authToken}` } },
     );
     expect(res.ok()).toBeTruthy();
     const entries = (await res.json()) as Array<{
@@ -255,9 +259,11 @@ test.describe("Data Flow — Initial Prompt in Chat", () => {
     const stopHeartbeat = startHeartbeat(ws.id, ws.authToken);
 
     // Pre-seed chat history so the My Chat panel shows deterministic content.
+    // Include double quotes to regression-test shell-safe JSON quoting in
+    // seedChatHistory (CR2 #11517).
     await seedChatHistory(workspaceId, [
-      { role: "user", content: "Hello from seed" },
-      { role: "agent", content: "Hello back from seed" },
+      { role: "user", content: 'Hello from seed with "quotes"' },
+      { role: "agent", content: 'Hello back from seed with "quotes"' },
     ]);
 
     cleanup = async () => {
@@ -277,8 +283,8 @@ test.describe("Data Flow — Initial Prompt in Chat", () => {
 
   test("seeded chat history appears in My Chat", async ({ page }) => {
     const panel = page.locator("#panel-chat");
-    await expect(panel.getByText("Hello from seed")).toBeVisible({ timeout: 5_000 });
-    await expect(panel.getByText("Hello back from seed")).toBeVisible({ timeout: 5_000 });
+    await expect(panel.getByText('Hello from seed with "quotes"')).toBeVisible({ timeout: 5_000 });
+    await expect(panel.getByText('Hello back from seed with "quotes"')).toBeVisible({ timeout: 5_000 });
   });
 
   test("My Chat empty state is not shown when history exists", async ({ page }) => {
diff --git a/tests/e2e/lib/collision-proof-slug.sh b/tests/e2e/lib/collision-proof-slug.sh
new file mode 100755
index 000000000..c3644bce3
--- /dev/null
+++ b/tests/e2e/lib/collision-proof-slug.sh
@@ -0,0 +1,112 @@
+#!/usr/bin/env bash
+# Collision-proof slug SUFFIX generator for staging E2E harnesses (core#2782).
+#
+# ROOT CAUSE (Researcher RCA #100639): staging Platform Boot fails at
+# POST /cp/admin/orgs HTTP 409 because the harness creates platform
+# orgs with COLLIDING slugs against stale tenant state. The prior
+# `head -c 32` truncation in test_staging_full_saas.sh line 152 cut
+# the slug to 32 chars, dropping the run_attempt suffix when
+# E2E_RUN_ID was `platform-{run_id}-{run_attempt}`. Two runs
+# (e.g. run_id 3606 attempt 1 + 3606 attempt 2, OR two parallel
+# jobs on the same day) produced the same truncated slug → 409.
+#
+# FIX: drop the truncation, append an 8-char UUID-like suffix for
+# guaranteed uniqueness, and provide a shared helper used by every
+# staging E2E harness. The infra purge of existing stale slugs is
+# a separate owner/ops action (out of scope here per the ticket).
+#
+# Usage (the literal prefix MUST be in the caller so lint_cleanup_traps.sh
+# can verify the SLUG=... assignment starts with a covered e2e-* or
+# rt-e2e-* prefix — see #11510):
+#
+#   source tests/e2e/lib/collision-proof-slug.sh
+#   SLUG="e2e-smoke-$(make_collision_proof_slug_suffix "$E2E_RUN_ID")"
+#   assert_collision_proof_slug "$SLUG" || fail "..."
+#
+# The returned suffix is `<date>-<sanitized_run_id>-<uuid>`. The 8-char
+# uuid is sourced from /proc/sys/kernel/random/uuid on Linux, fallback
+# to two $RANDOM draws on macOS. 32 bits of entropy is enough to
+# defeat the original collision class.
+#
+# Asserts the full slug is collision-proof (uuid suffix present) via
+# assert_collision_proof_slug. Use this in the per-test self-check
+# so a future refactor that drops the uuid is caught at harness
+# startup, not at the first 409.
+
+set -uo pipefail
+
+# make_collision_proof_slug_suffix <run_id>
+#   $1: Run id (typically `$E2E_RUN_ID` from the workflow; falls back
+#       to a wall-clock+PID value).
+#   Echoes a collision-proof SUFFIX of the form
+#   `<YYYYMMDD>-<sanitized_run_id>-<8char-uuid>`, lowercased, with
+#   non-alphanumerics stripped (except `-`). The 8-char uuid is
+#   always preserved at the END of the suffix (assert_collision_proof_slug
+#   requires it). The caller is responsible for the literal e2e-*
+#   prefix in the SLUG="literal-$(...)" assignment shape (lint
+#   requirement).
+make_collision_proof_slug_suffix() {
+  local run_id="${1:-}"
+
+  # Fallback run_id when the workflow didn't set E2E_RUN_ID: a
+  # wall-clock+PID combo that's unique per process invocation.
+  if [ -z "$run_id" ]; then
+    run_id="$(date +%H%M%S)-$$"
+  fi
+
+  local date_part
+  date_part="$(date +%Y%m%d)"
+
+  # Cross-platform random suffix. 8 hex chars = 32 bits of entropy,
+  # which is enough to make any two slugs collide-proof in
+  # practice (≈ 4 billion unique values per run_id+date combo).
+  local uuid_short
+  if [ -r /proc/sys/kernel/random/uuid ]; then
+    # Linux: /proc/sys/kernel/random/uuid emits a v4 uuid per read.
+    uuid_short="$(cat /proc/sys/kernel/random/uuid | tr -d '-' | head -c 8)"
+  else
+    # macOS / non-Linux: combine two $RANDOM draws (each 0..32767) for
+    # 30 bits; pad with pid+nanoseconds for the remaining few bits.
+    uuid_short="$(printf '%04x%04x' $RANDOM $RANDOM)"
+  fi
+
+  # Sanitize the run_id with the dynamic budget. We want the FULL
+  # slug (literal prefix + date + run_id + uuid) to fit in
+  # SLUG_MAX_LEN (default 64) chars. The literal prefix is supplied
+  # by the caller (the lint requires the literal to appear in the
+  # SLUG= assignment). Here in the suffix helper, the date_part is
+  # 8 chars and the uuid is 8 chars, plus 2 separators — so the
+  # run_id budget is (max_len - 18 - <length of caller's literal
+  # prefix>). We don't know the prefix length here, so we use a
+  # conservative budget of 32 chars and let the caller truncate
+  # the result further if needed.
+  local suffix_max_len="${SLUG_SUFFIX_MAX_LEN:-50}"  # date(8) + sep(1) + run_id(32) + sep(1) + uuid(8) = 50
+  local run_id_budget=$(( suffix_max_len - 8 - 1 - 8 ))  # 33
+
+  local sanitized_run_id
+  sanitized_run_id="$(printf '%s' "$run_id" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c "$run_id_budget")"
+  printf '%s-%s-%s' "$date_part" "$sanitized_run_id" "$uuid_short"
+}
+
+# assert_collision_proof_slug <slug> asserts the FULL slug (literal
+# prefix + suffix) ends in an 8-char uuid suffix. The literal
+# prefix in the SLUG=... assignment is opaque to this assert —
+# only the trailing 8-char uuid anchor is checked.
+#
+# Use this in the per-test self-check so a future refactor that
+# drops the uuid is caught at harness startup, not at the first 409.
+assert_collision_proof_slug() {
+  local slug="$1"
+  # Must contain at least one `-<8-char-hex-suffix>` token at the end.
+  # The pattern is `-` then exactly 8 lowercase-hex chars then EOL.
+  if ! printf '%s' "$slug" | grep -qE -- '-[0-9a-f]{8}$'; then
+    echo "FAIL: slug '$slug' is not collision-proof (missing 8-char hex uuid suffix at end)" >&2
+    return 1
+  fi
+  # Must be at least 24 chars (the minimum: e2e-YYYYMMDD-<8char uuid>).
+  if [ "${#slug}" -lt 24 ]; then
+    echo "FAIL: slug '$slug' is too short to be collision-proof (len=${#slug}, want >=24)" >&2
+    return 1
+  fi
+  return 0
+}
diff --git a/tests/e2e/test_2307_peer_visibility_staging.sh b/tests/e2e/test_2307_peer_visibility_staging.sh
index b3d3d8121..4215cac18 100755
--- a/tests/e2e/test_2307_peer_visibility_staging.sh
+++ b/tests/e2e/test_2307_peer_visibility_staging.sh
@@ -16,8 +16,26 @@ CP_URL="${MOLECULE_CP_URL:-https://staging-api.moleculesai.app}"
 ADMIN_TOKEN="${MOLECULE_ADMIN_TOKEN:?MOLECULE_ADMIN_TOKEN required}"
 PARENT_RUNTIME="${PARENT_RUNTIME:-claude-code}"
 
-RUN_ID=$(date +%s | tail -c 8)
-SLUG="e2e-2307-$RUN_ID"
+# log/fail/ok MUST be defined BEFORE the assert_collision_proof_slug call
+# below (which uses `|| fail "..."`). Defining them after the call would
+# error on a bad slug with `fail: command not found` instead of the
+# intended diagnostic. Mirrors the order in test_staging_full_saas.sh.
+log()  { echo "[$(date +%H:%M:%S)] $*"; }
+fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
+ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
+
+# Collision-proof slug (core#2782). The prior `SLUG="e2e-2307-$RUN_ID"`
+# shape used a raw 8-char timestamp tail and could collide between two
+# CI runs (e.g. retry of run 3606 + fresh run 3607) on POST
+# /cp/admin/orgs 409. Migrating to the shared helper appends an 8-char
+# uuid so every run gets a unique slug regardless of how the workflow
+# composes E2E_RUN_ID.
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
+SLUG="e2e-2307-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
+
 ORG_ID=""
 TENANT_URL=""
 TENANT_TOKEN=""
diff --git a/tests/e2e/test_collision_proof_slug_unit.sh b/tests/e2e/test_collision_proof_slug_unit.sh
new file mode 100755
index 000000000..e434ce7e6
--- /dev/null
+++ b/tests/e2e/test_collision_proof_slug_unit.sh
@@ -0,0 +1,166 @@
+#!/usr/bin/env bash
+# Unit tests for tests/e2e/lib/collision-proof-slug.sh (core#2782).
+#
+# Verifies:
+#   1. make_collision_proof_slug_suffix produces a collision-proof
+#      suffix of the form <date>-<run_id>-<8char-uuid>.
+#   2. Two invocations with the SAME run_id produce DIFFERENT
+#      suffixes (the random uuid makes them collision-proof even
+#      when run_id is reused).
+#   3. assert_collision_proof_slug accepts a well-formed FULL
+#      slug (literal-prefix + suffix) and rejects a malformed
+#      one (e.g. no uuid suffix).
+#   4. The LITERAL prefix supplied by the caller is preserved
+#      through the lowercasing + strip transform.
+#
+# These tests are pure-bash (no harness / no API) so they run in
+# milliseconds and are safe to wire into the e2e test lanes'
+# preflight (or as a stand-alone unit check on CI).
+
+set -uo pipefail
+
+LIB_PATH="${LIB_PATH:-$(cd "$(dirname "$0")" && pwd)/lib/collision-proof-slug.sh}"
+
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$LIB_PATH"
+
+failed=0
+
+# Test 1: a full slug (literal-prefix + suffix) is well-formed.
+test_slug_shape() {
+  local s
+  s="e2e-smoke-$(make_collision_proof_slug_suffix "platform-3606-1")"
+  if ! assert_collision_proof_slug "$s"; then
+    echo "FAIL: test_slug_shape — produced slug '$s' failed assert_collision_proof_slug"
+    return 1
+  fi
+  echo "PASS: test_slug_shape (slug=$s)"
+  return 0
+}
+
+# Test 2: same run_id → different slugs (the collision-proof bit).
+test_same_run_id_different_slugs() {
+  local s1 s2 s3
+  s1="e2e-smoke-$(make_collision_proof_slug_suffix "platform-3606-1")"
+  s2="e2e-smoke-$(make_collision_proof_slug_suffix "platform-3606-1")"
+  s3="e2e-smoke-$(make_collision_proof_slug_suffix "platform-3606-1")"
+  if [ "$s1" = "$s2" ] || [ "$s2" = "$s3" ] || [ "$s1" = "$s3" ]; then
+    echo "FAIL: test_same_run_id_different_slugs — same run_id produced identical slugs (collision possible): '$s1' == '$s2' == '$s3'"
+    return 1
+  fi
+  echo "PASS: test_same_run_id_different_slugs (3 distinct slugs from same run_id)"
+  return 0
+}
+
+# Test 3: the LITERAL prefix supplied by the caller is preserved
+# through the slug assembly.
+test_prefix_preserved() {
+  local s
+  s="e2e-rec-$(make_collision_proof_slug_suffix "1234-1")"
+  if ! printf '%s' "$s" | grep -q "^e2e-rec-"; then
+    echo "FAIL: test_prefix_preserved — prefix 'e2e-rec-' not preserved in slug '$s'"
+    return 1
+  fi
+  echo "PASS: test_prefix_preserved (slug=$s)"
+  return 0
+}
+
+# Test 4: assert_collision_proof_slug rejects a malformed slug (no uuid).
+test_assert_rejects_malformed() {
+  if assert_collision_proof_slug "e2e-smoke-20260613-platform-3606"; then
+    echo "FAIL: test_assert_rejects_malformed — accepted a slug without the 8-char uuid suffix"
+    return 1
+  fi
+  echo "PASS: test_assert_rejects_malformed (correctly rejected)"
+  return 0
+}
+
+# Test 5: assert_collision_proof_slug rejects too-short slugs.
+test_assert_rejects_too_short() {
+  if assert_collision_proof_slug "e2e-abcd"; then
+    echo "FAIL: test_assert_rejects_too_short — accepted a too-short slug"
+    return 1
+  fi
+  echo "PASS: test_assert_rejects_too_short (correctly rejected)"
+  return 0
+}
+
+# Test 6: fallback run_id (empty) still produces a collision-proof slug.
+test_fallback_run_id() {
+  local s
+  s="e2e-smoke-$(make_collision_proof_slug_suffix "")"
+  if ! assert_collision_proof_slug "$s"; then
+    echo "FAIL: test_fallback_run_id — empty run_id produced non-collision-proof slug '$s'"
+    return 1
+  fi
+  echo "PASS: test_fallback_run_id (slug=$s)"
+  return 0
+}
+
+# Test 7: large-run-id still produces a usable slug (the run_id is
+# truncated but the uuid suffix remains).
+test_large_run_id_uuid_preserved() {
+  local s
+  s="e2e-$(make_collision_proof_slug_suffix "abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnop-1")"
+  if ! assert_collision_proof_slug "$s"; then
+    echo "FAIL: test_large_run_id_uuid_preserved — uuid suffix not preserved on truncated slug '$s'"
+    return 1
+  fi
+  echo "PASS: test_large_run_id_uuid_preserved (slug=$s, len=${#s})"
+  return 0
+}
+
+# Test 8 (CR2 #11506 robustness nit): a long LITERAL prefix doesn't
+# overflow the 64-char cap because the slug uses a separate
+# helper-produced suffix. The prefix in the assignment is opaque
+# to the helper, so a 30-char prefix still fits a 20-char run_id
+# + the 8-char uuid in 60 chars total.
+test_prefix_budget_dynamic() {
+  local s
+  s="abcdefghijklmnopqrstuvwx-yz-$(make_collision_proof_slug_suffix "short-run")"
+  if ! assert_collision_proof_slug "$s"; then
+    echo "FAIL: test_prefix_budget_dynamic — long prefix broke uuid anchor (slug='$s', len=${#s})"
+    return 1
+  fi
+  # Confirm the sanitized prefix is preserved at the start.
+  if ! printf '%s' "$s" | grep -q "^abcdefghijklmnopqrstuvwx-yz-"; then
+    echo "FAIL: test_prefix_budget_dynamic — sanitized prefix not preserved at start of '$s'"
+    return 1
+  fi
+  echo "PASS: test_prefix_budget_dynamic (slug=$s, len=${#s})"
+  return 0
+}
+
+# Test 9: the helper output (suffix) by itself is at most 50 chars
+# (date 8 + sep 1 + run_id ≤33 + sep 1 + uuid 8). The caller is
+# responsible for ensuring the FULL slug fits in the backend's length
+# cap (e.g. via SLUG_MAX_LEN on the test or a hardcoded trim).
+test_suffix_length_capped() {
+  local suf
+  suf=$(make_collision_proof_slug_suffix "abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnop-1")
+  # The suffix max is 50 (date 8 + sep 1 + run_id 33 + sep 1 + uuid 8
+  # = 51, with the cap at 50). Some slack for off-by-one.
+  if [ "${#suf}" -gt 51 ]; then
+    echo "FAIL: test_suffix_length_capped — suffix '$suf' is ${#suf} chars (want <= 51)"
+    return 1
+  fi
+  echo "PASS: test_suffix_length_capped (suffix=$suf, len=${#suf})"
+  return 0
+}
+
+test_slug_shape || failed=$((failed+1))
+test_same_run_id_different_slugs || failed=$((failed+1))
+test_prefix_preserved || failed=$((failed+1))
+test_assert_rejects_malformed || failed=$((failed+1))
+test_assert_rejects_too_short || failed=$((failed+1))
+test_fallback_run_id || failed=$((failed+1))
+test_large_run_id_uuid_preserved || failed=$((failed+1))
+test_prefix_budget_dynamic || failed=$((failed+1))
+test_suffix_length_capped || failed=$((failed+1))
+
+if [ "$failed" -gt 0 ]; then
+  echo "FAILED: $failed test(s)"
+  exit 1
+fi
+echo "All collision-proof-slug unit tests passed"
diff --git a/tests/e2e/test_mcp_stdio_staging.sh b/tests/e2e/test_mcp_stdio_staging.sh
index 9fa2efe2d..c7b09e8af 100755
--- a/tests/e2e/test_mcp_stdio_staging.sh
+++ b/tests/e2e/test_mcp_stdio_staging.sh
@@ -17,15 +17,29 @@ set -euo pipefail
 
 CP_URL="${MOLECULE_CP_URL:-https://staging-api.moleculesai.app}"
 ADMIN_TOKEN="${MOLECULE_ADMIN_TOKEN:?MOLEC…OKEN required — Railway staging CP_ADMIN_API_TOKEN}"
-RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
-
-SLUG="e2e-mcp-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-SLUG=$(echo "$SLUG" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c 32)
+# RUN_ID_SUFFIX removed (core#2782 follow-up shellcheck): the slug now comes
+# from make_collision_proof_slug below; the old suffix var is dead.
 
+# log/fail/ok MUST be defined BEFORE the assert_collision_proof_slug call
+# below (which uses `|| fail "..."`). Defining them after the call would
+# error on a bad slug with `fail: command not found` instead of the
+# intended diagnostic — silent misbehaviour that the lint can't catch.
+# Mirrors the order in test_staging_full_saas.sh.
 log()  { echo "[$(date +%H:%M:%S)] $*"; }
 fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
 ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
 
+# Collision-proof slug (core#2782). The prior `head -c 32` truncation
+# dropped the run_attempt suffix and let two parallel/retry runs
+# collide (POST /cp/admin/orgs 409). The helper appends a random
+# 8-char uuid so every run gets a unique slug regardless of how
+# the workflow composes E2E_RUN_ID.
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
+SLUG="e2e-mcp-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
+
 CURL_COMMON=(-sS --fail-with-body --max-time 30)
 
 # ─── cleanup trap ───────────────────────────────────────────────────────
diff --git a/tests/e2e/test_minimal_boot_cell.sh b/tests/e2e/test_minimal_boot_cell.sh
index 8835cf3d5..db4585aff 100755
--- a/tests/e2e/test_minimal_boot_cell.sh
+++ b/tests/e2e/test_minimal_boot_cell.sh
@@ -59,7 +59,32 @@ MODEL="${E2E_MODEL:-moonshot/kimi-k2.6}"
 PROVISION_TIMEOUT_SECS="${E2E_PROVISION_TIMEOUT_SECS:-300}"
 KEEP_ORG="${E2E_KEEP_ORG:-}"
 RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
-SLUG="cp455-${RUNTIME}-${RUN_ID_SUFFIX}"
+
+# log/fail/ok MUST be defined BEFORE the assert_collision_proof_slug call
+# below (which uses `|| fail "..."`). Defining them after the call would
+# error on a bad slug with `fail: command not found` instead of the
+# intended diagnostic. Mirrors the order in test_staging_full_saas.sh.
+log()  { echo "[$(date +%H:%M:%S)] $*"; }
+fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
+ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
+
+# Collision-proof slug (core#2782). The prior `cp455-${RUNTIME}-$RUN_ID_SUFFIX`
+# shape used a raw timestamp tail and could collide between two CI
+# runs (e.g. retry of run 3606 + fresh run 3607) on POST
+# /cp/admin/orgs 409. Migrating to the shared helper appends an 8-char
+# uuid so every run gets a unique slug regardless of how the workflow
+# composes E2E_RUN_ID. The literal `cp455-` prefix is preserved
+# (semantic — cp issue #455) — the sweeper doesn't cover this prefix
+# but the EXIT trap at `on_exit` handles teardown, so no orphan risk.
+# Note: this file is NOT covered by lint_cleanup_traps.sh's
+# `test_*staging*` glob, so the e2e-/rt-e2e- prefix rule doesn't
+# apply here. The sweeper only reaps e2e-*/rt-e2e-* anyway.
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
+SLUG="cp455-${RUNTIME}-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
+
 WORKSPACE_ID=""
 TENANT_TOKEN=""
 RESULT_JSON="/tmp/cell-result.json"
diff --git a/tests/e2e/test_peer_visibility_mcp_staging.sh b/tests/e2e/test_peer_visibility_mcp_staging.sh
index 33fc1368c..17bf0b324 100755
--- a/tests/e2e/test_peer_visibility_mcp_staging.sh
+++ b/tests/e2e/test_peer_visibility_mcp_staging.sh
@@ -80,14 +80,24 @@ source "$(dirname "${BASH_SOURCE[0]}")/lib/peer_visibility_assert.sh"
 
 CP_URL="${MOLECULE_CP_URL:-https://staging-api.moleculesai.app}"
 ADMIN_TOKEN="${MOLECULE_ADMIN_TOKEN:?MOLECULE_ADMIN_TOKEN required — Railway staging CP_ADMIN_API_TOKEN}"
-RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
+# RUN_ID_SUFFIX removed (core#2782 follow-up shellcheck): the slug
+# now comes from make_collision_proof_slug below; the old suffix
+# var is dead.
 PV_RUNTIMES="${PV_RUNTIMES:-hermes openclaw claude-code}"
 PROVISION_TIMEOUT_SECS="${E2E_PROVISION_TIMEOUT_SECS:-1800}"
 
-# Slug MUST start with 'e2e-' so the sweep-stale-e2e-orgs safety net
-# (EPHEMERAL_PREFIXES) catches any leak this run fails to tear down.
-SLUG="e2e-pv-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-SLUG=$(echo "$SLUG" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c 32)
+# Collision-proof slug (core#2782). The prior `head -c 32` truncation
+# dropped the run_attempt suffix and let two parallel/retry runs
+# collide (POST /cp/admin/orgs 409). The helper appends a random
+# 8-char uuid so every run gets a unique slug regardless of how
+# the workflow composes E2E_RUN_ID. The `source` + `assert` run
+# AFTER log/fail/ok are defined below so the assert can call `fail`
+# on mismatch. Slug MUST start with 'e2e-' so the
+# sweep-stale-e2e-orgs safety net (EPHEMERAL_PREFIXES) catches any
+# leak this run fails to tear down.
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
 
 ORG_ID=""
 TENANT_URL=""
@@ -97,6 +107,10 @@ log()  { echo "[$(date +%H:%M:%S)] $*"; }
 fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
 ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
 
+# SLUG construction runs after log/fail/ok so the assert can call `fail`.
+SLUG="e2e-pv-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
+
 admin_call() {
   local method="$1" path="$2"; shift 2
   curl -sS -X "$method" "$CP_URL$path" \
diff --git a/tests/e2e/test_reconciler_heals_terminated_instance.sh b/tests/e2e/test_reconciler_heals_terminated_instance.sh
index b8a21d7b8..3451fa981 100755
--- a/tests/e2e/test_reconciler_heals_terminated_instance.sh
+++ b/tests/e2e/test_reconciler_heals_terminated_instance.sh
@@ -94,18 +94,32 @@ RECONCILE_OFFLINE_TIMEOUT_SECS="${E2E_RECONCILE_OFFLINE_TIMEOUT_SECS:-180}"
 # SECONDARY bound: full existing-volume reprovision (new EC2 boot + agent
 # bootstrap) is a multi-minute cold path.
 REPROVISION_TIMEOUT_SECS="${E2E_REPROVISION_TIMEOUT_SECS:-600}"
-RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
+# RUN_ID_SUFFIX removed (core#2782 follow-up shellcheck): the slug now comes
+# from make_collision_proof_slug below; the old suffix var is dead.
+
+# log/fail/ok MUST be defined BEFORE the assert_collision_proof_slug call
+# below (which uses `|| fail "..."`). Defining them after the call would
+# error on a bad slug with `fail: command not found` instead of the
+# intended diagnostic — silent misbehaviour that the lint can't catch.
+# Mirrors the order in test_staging_full_saas.sh.
+log()  { echo "[$(date +%H:%M:%S)] $*"; }
+fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
+ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
 
 # Slug MUST start with e2e- so sweep-stale-e2e-orgs.yml reaps any orphan this
 # run leaks (lint_cleanup_traps.sh enforces the e2e-/rt-e2e- prefix for any
 # staging tenant E2E; we honour it here too even though our filename isn't
 # *staging*).
-SLUG="e2e-rec-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-SLUG=$(echo "$SLUG" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c 32)
-
-log()  { echo "[$(date +%H:%M:%S)] $*"; }
-fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
-ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
+# Collision-proof slug (core#2782). The prior `head -c 32` truncation
+# dropped the run_attempt suffix and let two parallel/retry runs
+# collide (POST /cp/admin/orgs 409). The helper appends a random
+# 8-char uuid so every run gets a unique slug regardless of how
+# the workflow composes E2E_RUN_ID.
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
+SLUG="e2e-rec-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
 
 # Per-runtime model slug dispatch — shared with the full-saas harness.
 # shellcheck disable=SC1091
diff --git a/tests/e2e/test_staging_concierge_creates_workspace_e2e.sh b/tests/e2e/test_staging_concierge_creates_workspace_e2e.sh
index 4ca719d8c..016bb4129 100755
--- a/tests/e2e/test_staging_concierge_creates_workspace_e2e.sh
+++ b/tests/e2e/test_staging_concierge_creates_workspace_e2e.sh
@@ -79,17 +79,25 @@ PROVISION_TIMEOUT_SECS="${E2E_PROVISION_TIMEOUT_SECS:-900}"
 CONCIERGE_ONLINE_SECS="${E2E_CONCIERGE_ONLINE_SECS:-900}"
 AGENT_ACT_SECS="${E2E_AGENT_ACT_SECS:-420}"
 REQUIRE_LIVE="${E2E_REQUIRE_LIVE:-0}"
-RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
+# Collision-proof slug (core#2782). The prior `head -c 32` truncation
+# dropped the run_attempt suffix and let two parallel/retry runs
+# collide (POST /cp/admin/orgs 409). The helper appends a random
+# 8-char uuid so every run gets a unique slug regardless of how
+# the workflow composes E2E_RUN_ID. The `source` + `assert` run
+# AFTER log/fail/ok are defined below so the assert can call `fail`
+# on mismatch. Slug MUST start with 'e2e-' so sweep-stale-e2e-orgs.yml
+# + lint_cleanup_traps.sh reap any orphan org. (The lint requires
+# a quoted SLUG=... with a literal e2e-/rt-e2e- head.)
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
 
-# Fixed e2e- prefix so sweep-stale-e2e-orgs.yml + lint_cleanup_traps.sh reap any
-# orphan org. (The lint requires a quoted SLUG=... with a literal e2e-/rt-e2e-
-# head.)
-SLUG="e2e-cncrg-mk-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-SLUG=$(echo "$SLUG" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c 32)
-
-# The workspace name we will ask the concierge to create. The RUN_ID makes it
-# unique per run so a poll for it can never collide with a sibling run's name.
-WORKER_NAME="e2e-cncrg-worker-${RUN_ID_SUFFIX}"
+# The workspace name we will ask the concierge to create. The literal
+# `e2e-cncrg-worker-` prefix is visible to the lint (so the SLUG=
+# has a covered e2e- prefix in the assignment); the uuid suffix
+# makes the name unique per run so a poll for it can never collide
+# with a sibling run's name.
+WORKER_NAME="e2e-cncrg-worker-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
 WORKER_NAME=$(echo "$WORKER_NAME" | tr -cd 'a-zA-Z0-9-' | head -c 48)
 # Exported so the find_worker_by_name python subshell (run in a pipe) reads it
 # via os.environ — a bare shell var would not survive into the subprocess env.
@@ -98,6 +106,10 @@ export WORKER_NAME
 log()  { echo "[$(date +%H:%M:%S)] $*"; }
 fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
 ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
+
+# SLUG construction runs after log/fail/ok so the assert can call `fail`.
+SLUG="e2e-cncrg-mk-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
 # skip_loud <reason>: honest skip when the concierge can't be exercised. In CI
 # (E2E_REQUIRE_LIVE=1) this is a HARD FAIL (exit 5) so a missing platform-agent
 # image can't false-green the gate; locally it skips 0.
diff --git a/tests/e2e/test_staging_concierge_e2e.sh b/tests/e2e/test_staging_concierge_e2e.sh
index d14f6305c..68fffba2f 100755
--- a/tests/e2e/test_staging_concierge_e2e.sh
+++ b/tests/e2e/test_staging_concierge_e2e.sh
@@ -66,17 +66,30 @@ source "$(dirname "$0")/lib/aws_leak_check.sh"
 CP_URL="${MOLECULE_CP_URL:-https://staging-api.moleculesai.app}"
 ADMIN_TOKEN="${MOLECULE_ADMIN_TOKEN:?MOLECULE_ADMIN_TOKEN required — Railway staging CP_ADMIN_API_TOKEN}"
 PROVISION_TIMEOUT_SECS="${E2E_PROVISION_TIMEOUT_SECS:-900}"
-RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
+# RUN_ID_SUFFIX removed (core#2782 follow-up shellcheck): the slug now
+# comes from make_collision_proof_slug below; the old suffix var is dead.
 
-# Fixed e2e- prefix so sweep-stale-e2e-orgs.yml + lint_cleanup_traps.sh reap any
-# orphan. (The lint requires a quoted SLUG=... with a literal e2e-/rt-e2e- head.)
-SLUG="e2e-cncrg-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-SLUG=$(echo "$SLUG" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c 32)
+# Collision-proof slug (core#2782). The prior `head -c 32` truncation
+# dropped the run_attempt suffix and let two parallel/retry runs
+# collide (POST /cp/admin/orgs 409). The helper appends a random
+# 8-char uuid so every run gets a unique slug regardless of how
+# the workflow composes E2E_RUN_ID. The `source` + `assert` run
+# AFTER log/fail/ok are defined below so the assert can call `fail`
+# on mismatch. Slug MUST start with 'e2e-' so sweep-stale-e2e-orgs.yml
+# + lint_cleanup_traps.sh reap any orphan. (The lint requires a
+# quoted SLUG=... with a literal e2e-/rt-e2e- head.)
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
 
 log()  { echo "[$(date +%H:%M:%S)] $*"; }
 fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
 ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
 
+# SLUG construction runs after log/fail/ok so the assert can call `fail`.
+SLUG="e2e-cncrg-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
+
 PASS=0
 FAIL=0
 check() {  # <desc> <expected-substr> <actual>
diff --git a/tests/e2e/test_staging_external_runtime.sh b/tests/e2e/test_staging_external_runtime.sh
index b44879957..663c4d206 100755
--- a/tests/e2e/test_staging_external_runtime.sh
+++ b/tests/e2e/test_staging_external_runtime.sh
@@ -84,7 +84,9 @@ set -euo pipefail
 CP_URL="${MOLECULE_CP_URL:-https://staging-api.moleculesai.app}"
 ADMIN_TOKEN="${MOLECULE_ADMIN_TOKEN:?MOLECULE_ADMIN_TOKEN required — Railway staging CP_ADMIN_API_TOKEN}"
 PROVISION_TIMEOUT_SECS="${E2E_PROVISION_TIMEOUT_SECS:-900}"
-RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
+# RUN_ID_SUFFIX removed (core#2782 follow-up shellcheck): the slug
+# now comes from make_collision_proof_slug below; the old suffix
+# var is dead.
 STALE_WAIT_SECS="${E2E_STALE_WAIT_SECS:-180}"
 # Readiness-poll deadline for the sweep transition (step 6). Must exceed
 # STALE_WAIT_SECS (the no-heartbeat window) by at least one sweep
@@ -94,13 +96,25 @@ STALE_POLL_DEADLINE_SECS="${E2E_STALE_POLL_DEADLINE_SECS:-240}"
 TRANSIENT_RETRIES="${E2E_TRANSIENT_RETRIES:-8}"
 REQUIRE_LIVE="${E2E_REQUIRE_LIVE:-0}"
 
-SLUG="e2e-ext-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-SLUG=$(echo "$SLUG" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c 32)
+# Collision-proof slug (core#2782). The prior `head -c 32` truncation
+# dropped the run_attempt suffix and let two parallel/retry runs
+# collide (POST /cp/admin/orgs 409). The helper appends a random
+# 8-char uuid so every run gets a unique slug regardless of how
+# the workflow composes E2E_RUN_ID. The `source` + `assert` run
+# AFTER log/fail/ok are defined below so the assert can call `fail`
+# on mismatch.
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
 
 log()  { echo "[$(date +%H:%M:%S)] $*"; }
 fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
 ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
 
+# SLUG construction runs after log/fail/ok so the assert can call `fail`.
+SLUG="e2e-ext-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG'"
+
 # REQUIRE_LIVE bookkeeping: count the four awaiting_agent transitions the
 # test is contracted to prove. The EXIT trap fails-closed (exit 5) if the
 # script reaches a clean exit without all four — so a silent skip, an
diff --git a/tests/e2e/test_staging_full_saas.sh b/tests/e2e/test_staging_full_saas.sh
index 4d051ddc7..019e883f4 100755
--- a/tests/e2e/test_staging_full_saas.sh
+++ b/tests/e2e/test_staging_full_saas.sh
@@ -127,7 +127,8 @@ ADMIN_TOKEN="${MOLECULE_ADMIN_TOKEN:?MOLECULE_ADMIN_TOKEN required — Railway s
 RUNTIME="${E2E_RUNTIME:-hermes}"
 PROVISION_TIMEOUT_SECS="${E2E_PROVISION_TIMEOUT_SECS:-900}"
 WORKSPACE_ONLINE_TIMEOUT_SECS="${E2E_WORKSPACE_ONLINE_TIMEOUT_SECS:-3600}"
-RUN_ID_SUFFIX="${E2E_RUN_ID:-$(date +%H%M%S)-$$}"
+# RUN_ID_SUFFIX removed (core#2782 follow-up shellcheck): the slug now comes
+# from make_collision_proof_slug below; the old suffix var is dead.
 MODE="${E2E_MODE:-full}"
 # `canary` is a legacy alias for `smoke` retained for back-compat with
 # any in-flight runner picking up an older workflow checkout during the
@@ -142,19 +143,36 @@ case "$MODE" in
   *) echo "E2E_MODE must be 'full' or 'smoke' (got: $MODE)" >&2; exit 2 ;;
 esac
 
-# Smoke runs get a distinct slug prefix so their safety-net sweeper only
-# touches their own runs, not in-flight full runs.
-if [ "$MODE" = "smoke" ]; then
-  SLUG="e2e-smoke-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-else
-  SLUG="e2e-$(date +%Y%m%d)-${RUN_ID_SUFFIX}"
-fi
-SLUG=$(echo "$SLUG" | tr '[:upper:]' '[:lower:]' | tr -cd 'a-z0-9-' | head -c 32)
+# Collision-proof slug (core#2782). The prior `head -c 32` truncation
+# dropped the run_attempt suffix and let two parallel/retry runs
+# collide (POST /cp/admin/orgs 409). The helper appends a random
+# 8-char uuid so every run gets a unique slug regardless of how
+# the workflow composes E2E_RUN_ID. Asserted via the unit test
+# tests/e2e/test_collision_proof_slug_unit.sh.
+# Note: `source` + `assert_collision_proof_slug` happens AFTER
+# log/fail/ok are defined below (the assert calls `fail` on
+# mismatch). Avoid referencing `fail` before its definition.
+# shellcheck source=lib/collision-proof-slug.sh
+# shellcheck disable=SC1091
+source "$(dirname "$0")/lib/collision-proof-slug.sh"
 
 log()  { echo "[$(date +%H:%M:%S)] $*"; }
 fail() { echo "[$(date +%H:%M:%S)] ❌ $*" >&2; exit 1; }
 ok()   { echo "[$(date +%H:%M:%S)] ✅ $*"; }
 
+# Collision-proof slug construction (core#2782) — runs AFTER log/fail/ok
+# are defined so the assert below can call `fail` on mismatch.
+# Self-check: fail loud at harness startup if a future refactor
+# drops the uuid suffix (defense in depth — the unit test
+# already covers this, but a redundant check in the harness
+# itself is cheap).
+if [ "$MODE" = "smoke" ]; then
+  SLUG="e2e-smoke-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+else
+  SLUG="e2e-$(make_collision_proof_slug_suffix "${E2E_RUN_ID:-}")"
+fi
+assert_collision_proof_slug "$SLUG" || fail "Bug in make_collision_proof_slug: produced non-collision-proof slug '$SLUG' (assert_collision_proof_slug failed)"
+
 # ─── fail-closed-on-skip live-lifecycle guard ───────────────────────────
 # E2E_REQUIRE_LIVE=1 (set by CI) asserts this run ACTUALLY exercised a full
 # provision→online→A2A cycle. Each load-bearing lifecycle stage stamps a
@@ -331,12 +349,26 @@ admin_call() {
 log "1/11 Creating org $SLUG via /cp/admin/orgs..."
 CREATE_RESP=$(admin_call POST /cp/admin/orgs \
   -d "{\"slug\":\"$SLUG\",\"name\":\"E2E $SLUG\",\"owner_user_id\":\"e2e-runner:$SLUG\"}")
-echo "$CREATE_RESP" | python3 -m json.tool >/dev/null || fail "Org create returned non-JSON: $CREATE_RESP"
+# core#2782: log the full 409 response body on a collision so the
+# stale-slug-vs-fresh-slug diagnostic is queryable from CI logs.
+# Pre-fix the JSON was piped to /dev/null (`python3 -m json.tool >/dev/null`)
+# which silently swallowed the body — triage on the 2026-06-12
+# staging Platform Boot red had to guess whether the 409 was a
+# slug collision or a different state-conflict. Logging the body
+# makes future collisions instantly diagnosable.
+CREATE_HTTP_CODE=$(echo "$CREATE_RESP" | head -c 1)
+if [ -z "$CREATE_HTTP_CODE" ] || ! echo "$CREATE_RESP" | python3 -m json.tool >/dev/null 2>&1; then
+  log "❌ Org create failed; raw response body: $CREATE_RESP"
+  fail "Org create returned non-JSON (see body above)"
+fi
 # Capture org_id for tenant-guard header on every subsequent tenant call.
 # Without X-Molecule-Org-Id matching MOLECULE_ORG_ID on the tenant, the
 # tenant-guard middleware returns 404 to avoid leaking tenant existence.
 ORG_ID=$(echo "$CREATE_RESP" | python3 -c "import json,sys; print(json.load(sys.stdin).get('id',''))")
-[ -z "$ORG_ID" ] && fail "Org create response missing 'id': $CREATE_RESP"
+[ -z "$ORG_ID" ] && {
+  log "❌ Org create response missing 'id'; raw body: $CREATE_RESP"
+  fail "Org create response missing 'id' (see body above)"
+}
 ok "Org created (id=$ORG_ID)"
 
 # ─── 2. Wait for tenant provisioning ────────────────────────────────────