diff --git a/.github/workflows/gate.yml b/.github/workflows/gate.yml
index 13afe21..910c69f 100644
--- a/.github/workflows/gate.yml
+++ b/.github/workflows/gate.yml
@@ -47,11 +47,44 @@ jobs:
       - run: mix deps.get
 
       # Developer Certificate of Origin: every commit carries a sign-off (ADR-0012).
-      - name: DCO sign-off present on every commit
+      # Slice 128. This used to concatenate every message in the range and grep for one
+      # `Signed-off-by:` anywhere, under this same name: a range of five commits where one was
+      # signed passed a step called "on every commit". Now it asks per commit and prints the ones
+      # that fail.
+      #
+      # `--no-merges` for the reason `test/dco_test.exs` gives at length: a sign-off certifies the
+      # right to submit work, and a forge's merge commit introduces none. That test checks the whole
+      # history and runs on every leg; this step is the fast one that fails a pull request early,
+      # and the two agree on what they mean by "every commit".
+      # Slice 128. The owner's rule is that no assistant attribution appears anywhere, and a pull
+      # request description is somewhere: it is the first thing a reader of this project sees, and
+      # seven of them carried one on 2026-09-26 before a person noticed. The hook covers commit
+      # messages and plan_check covers history; both look at the tree, and a description is not in
+      # it.
+      #
+      # The body goes through `env` rather than into the script: `${{ }}` interpolated into a shell
+      # command is a script injection, and a pull request description is attacker-controlled text.
+      - name: No assistant attribution in the pull request description
+        if: github.event_name == 'pull_request'
+        env:
+          PR_BODY: ${{ github.event.pull_request.body }}
+        run: |
+          if printf '%s' "$PR_BODY" | grep -qiE 'Co-Authored-By: Claude|Claude-Session:|Generated with \[Claude'; then
+            echo "::error::the pull request description carries an assistant attribution; remove it"
+            exit 1
+          fi
+
+      - name: DCO sign-off on every commit that carries work
         run: |
-          git log --format=%B ${{ github.event.pull_request.base.sha || 'HEAD~1' }}..HEAD 2>/dev/null \
-            | grep -q '^Signed-off-by: ' || {
-              echo "::error::a commit in this range has no Signed-off-by line"; exit 1; }
+          range="${{ github.event.pull_request.base.sha || 'HEAD~1' }}..HEAD"
+          unsigned=$(git log --no-merges --format='%H%x09%(trailers:key=Signed-off-by,valueonly)' "$range" \
+            | awk -F'\t' '$2 == "" { print $1 }')
+          if [ -n "$unsigned" ]; then
+            for c in $unsigned; do
+              echo "::error::commit $c has no Signed-off-by line: $(git log -1 --format=%s "$c")"
+            done
+            exit 1
+          fi
 
       - run: mix gate
 
@@ -252,11 +285,44 @@ jobs:
           ERL_AFLAGS: "-eval application:load(crypto)"
         run: elixir scripts/crypto_supports.exs | diff - docs/fips-leg/supports-default.txt
 
-      - name: DCO sign-off present on every commit
+      # Slice 128. This used to concatenate every message in the range and grep for one
+      # `Signed-off-by:` anywhere, under this same name: a range of five commits where one was
+      # signed passed a step called "on every commit". Now it asks per commit and prints the ones
+      # that fail.
+      #
+      # `--no-merges` for the reason `test/dco_test.exs` gives at length: a sign-off certifies the
+      # right to submit work, and a forge's merge commit introduces none. That test checks the whole
+      # history and runs on every leg; this step is the fast one that fails a pull request early,
+      # and the two agree on what they mean by "every commit".
+      # Slice 128. The owner's rule is that no assistant attribution appears anywhere, and a pull
+      # request description is somewhere: it is the first thing a reader of this project sees, and
+      # seven of them carried one on 2026-09-26 before a person noticed. The hook covers commit
+      # messages and plan_check covers history; both look at the tree, and a description is not in
+      # it.
+      #
+      # The body goes through `env` rather than into the script: `${{ }}` interpolated into a shell
+      # command is a script injection, and a pull request description is attacker-controlled text.
+      - name: No assistant attribution in the pull request description
+        if: github.event_name == 'pull_request'
+        env:
+          PR_BODY: ${{ github.event.pull_request.body }}
+        run: |
+          if printf '%s' "$PR_BODY" | grep -qiE 'Co-Authored-By: Claude|Claude-Session:|Generated with \[Claude'; then
+            echo "::error::the pull request description carries an assistant attribution; remove it"
+            exit 1
+          fi
+
+      - name: DCO sign-off on every commit that carries work
         run: |
-          git log --format=%B ${{ github.event.pull_request.base.sha || 'HEAD~1' }}..HEAD 2>/dev/null \
-            | grep -q '^Signed-off-by: ' || {
-              echo "::error::a commit in this range has no Signed-off-by line"; exit 1; }
+          range="${{ github.event.pull_request.base.sha || 'HEAD~1' }}..HEAD"
+          unsigned=$(git log --no-merges --format='%H%x09%(trailers:key=Signed-off-by,valueonly)' "$range" \
+            | awk -F'\t' '$2 == "" { print $1 }')
+          if [ -n "$unsigned" ]; then
+            for c in $unsigned; do
+              echo "::error::commit $c has no Signed-off-by line: $(git log -1 --format=%s "$c")"
+            done
+            exit 1
+          fi
 
       - run: mix gate
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3404a7b..5d5f19a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,49 @@ evidence for each increment is retained by the maintainers and summarised here.
 
 ## 2026-09-26
 
+### `slice/128`: the checks that guard attribution now say what they check
+
+Three checks guard two rules: that no assistant attribution appears anywhere in this project's
+history, and that every commit carrying work is signed off by the person who wrote it. One was named
+for something it did not do, one contained an exception it could never reach, and none of them
+looked at a pull request description, which is the first thing a reader of this project sees.
+
+The first concatenated every message in a range and looked for a single sign-off anywhere, under a
+name that said it checked every commit. It now asks per commit and names each one that fails. The
+second consulted a list of excused commits from inside a loop that could never contain one, telling
+every reader that something was checked and excused when neither was true; the list is gone and the
+reason it is gone is written where it was. The third did not exist: descriptions are now checked,
+with the text passed to the check as data rather than spliced into a command, because a description
+is written by whoever opens the request.
+
+This does not change the project's position on merge commits, which is that a sign-off certifies the
+right to submit work and an automated merge introduces none. That was decided earlier and is left
+alone; what changed is that the checks now describe themselves accurately.
+
+Verified: gate green at exit 0; 914 tests passing; coverage 80.31%.
+
+### `slice/127`: a test that gives up waiting now says so
+
+A test helper that waits for something to happen returned the same answer whether it saw what it was
+waiting for or ran out of time. Every check written on top of it therefore reported a missing value
+rather than a wait that expired, which sends a reader looking for a fault that is not there. It did
+exactly that twice in one day: once as an intermittent failure on the slowest continuous-integration
+machine, and once by prompting an investigation into a defect that turned out not to exist.
+
+Waiting now raises when it gives up, and says how long it waited and everything it did see, because
+"waited and saw the work happening" and "waited and saw nothing at all" point at opposite causes.
+Twenty places that check what came back were moved onto it, and a check makes the old shape
+impossible to write again.
+
+The one deadline that had been missed was re-set from a measurement rather than a guess: the wait
+takes about 4.8 seconds locally, the previous limit was three times that and the slowest machine
+still missed it, so it is now twelve times. A generous limit costs nothing when the thing arrives,
+because the wait ends the moment it does.
+
+No change to the application itself; this is entirely about how the suite reports.
+
+Verified: gate green at exit 0; 910 tests passing; coverage 80.31%.
+
 ### `slice/026`: Trinity keeps working when the link goes down
 
 A site that loses its connection keeps operating, and the record of what it did survives the gap intact.
diff --git a/test/dco_range_test.exs b/test/dco_range_test.exs
new file mode 100644
index 0000000..be0da68
--- /dev/null
+++ b/test/dco_range_test.exs
@@ -0,0 +1,161 @@
+# SPDX-FileCopyrightText: Sudo Apt Holdings LLC
+# SPDX-License-Identifier: Apache-2.0
+defmodule DcoRangeTest do
+  @moduledoc """
+  Slice 128: the workflow's range check says "every commit" and checks "at least one".
+
+  `.github/workflows/gate.yml` carries a step named **DCO sign-off present on every commit** whose
+  body concatenates every message in the range and greps for one `Signed-off-by:` anywhere:
+
+      git log --format=%B BASE..HEAD | grep -q '^Signed-off-by: '
+
+  A range of five commits where one is signed passes it. `test/dco_test.exs` does check every
+  non-merge commit, over the whole history, on every leg, so the practical exposure is small. The
+  defect is that a step's name is a claim, and this one is false: a reader of the workflow, or of a
+  donation review, is told something the file does not do.
+
+  This test is about the logic rather than about the workflow's YAML, so it runs the same shape
+  against a range it builds itself.
+  """
+  use ExUnit.Case, async: true
+
+  @moduletag :tmp_dir
+
+  # The shape the workflow uses today, extracted so it can be run against a known range.
+  defp concatenated_grep(dir, range) do
+    {out, _} = System.cmd("git", ["log", "--format=%B", range], cd: dir)
+    if String.match?(out, ~r/^Signed-off-by: /m), do: :pass, else: :fail
+  end
+
+  # What the name promises: every commit in the range, individually.
+  defp every_commit(dir, range) do
+    {out, 0} =
+      System.cmd(
+        "git",
+        ["log", "--no-merges", "--format=%H%x09%(trailers:key=Signed-off-by,valueonly)", range],
+        cd: dir
+      )
+
+    unsigned =
+      out
+      |> String.split("\n", trim: true)
+      |> Enum.filter(fn line ->
+        case String.split(line, "\t") do
+          [_sha, trailer] -> String.trim(trailer) == ""
+          [_sha] -> true
+          _ -> false
+        end
+      end)
+
+    if unsigned == [], do: :pass, else: :fail
+  end
+
+  defp git(dir, args), do: {_, 0} = System.cmd("git", args, cd: dir)
+
+  defp repo_with_one_signed_one_not(dir) do
+    git(dir, ["init", "-q"])
+    git(dir, ["config", "user.name", "Test"])
+    git(dir, ["config", "user.email", "test@example.com"])
+    # This machine signs commits globally; a scratch repository has no key and would fail at 128.
+    git(dir, ["config", "commit.gpgsign", "false"])
+
+    git(dir, [
+      "commit",
+      "-q",
+      "--allow-empty",
+      "-m",
+      "base\n\nSigned-off-by: Test <test@example.com>"
+    ])
+
+    base = String.trim(elem(System.cmd("git", ["rev-parse", "HEAD"], cd: dir), 0))
+
+    git(dir, [
+      "commit",
+      "-q",
+      "--allow-empty",
+      "-m",
+      "signed\n\nSigned-off-by: Test <test@example.com>"
+    ])
+
+    git(dir, ["commit", "-q", "--allow-empty", "-m", "unsigned, no trailer at all"])
+    base
+  end
+
+  test "AC1: the step's current logic accepts a range containing an unsigned commit", %{
+    tmp_dir: dir
+  } do
+    base = repo_with_one_signed_one_not(dir)
+
+    assert concatenated_grep(dir, "#{base}..HEAD") == :pass,
+           "the concatenating grep rejected this range, so the premise of this slice is wrong"
+
+    assert every_commit(dir, "#{base}..HEAD") == :fail,
+           "a per-commit check should reject a range with an unsigned commit"
+  end
+
+  test "AC2: the workflow step now checks every commit, and both copies agree" do
+    yaml = File.read!(".github/workflows/gate.yml")
+
+    steps =
+      yaml
+      |> String.split("\n")
+      |> Enum.chunk_every(12, 1, :discard)
+      |> Enum.filter(fn chunk -> String.contains?(hd(chunk), "DCO sign-off") end)
+
+    assert length(steps) == 2,
+           "expected the DCO step in two legs, found #{length(steps)}"
+
+    for chunk <- steps do
+      body = Enum.join(chunk, "\n")
+
+      refute body =~ "grep -q '^Signed-off-by: '",
+             """
+             the step still concatenates the range and greps for one sign-off anywhere, which is \
+             not what its name says:
+
+             #{body}
+             """
+    end
+  end
+
+  describe "AC5: a pull request description is checked too" do
+    test "the workflow carries the step, in both legs, and passes the body through env" do
+      yaml = File.read!(".github/workflows/gate.yml")
+
+      assert length(
+               String.split(yaml, "No assistant attribution in the pull request description")
+             ) - 1 == 2,
+             "the PR-description check is not present in both legs"
+
+      assert yaml =~ "PR_BODY: ${{ github.event.pull_request.body }}",
+             "the body is not passed through env, which means it is interpolated into a shell " <>
+               "command; a pull request description is attacker-controlled text"
+
+      refute yaml =~ ~r/grep -qiE '[^']*'\s*<<<\s*"\$\{\{/,
+             "the body is interpolated directly into the script"
+    end
+
+    test "the pattern it uses catches the shapes that were found in the wild" do
+      # The seven descriptions on #99 to #105 carried the first of these. The others are the
+      # trailers the commit hook already strips, included so one check knows every shape.
+      pattern = ~r/Co-Authored-By: Claude|Claude-Session:|Generated with \[Claude/i
+
+      for body <- [
+            "some text\n\n🤖 Generated with [Claude Code](https://claude.com/claude-code)\n",
+            "Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>",
+            "Claude-Session: abc123",
+            "GENERATED WITH [CLAUDE CODE]"
+          ] do
+        assert Regex.match?(pattern, body), "the pattern misses: #{inspect(body)}"
+      end
+
+      for body <- [
+            "a normal description mentioning claude in prose",
+            "Signed-off-by: Ayla Croft <aylacroft@proton.me>",
+            "This slice was generated from a template"
+          ] do
+        refute Regex.match?(pattern, body), "the pattern over-matches: #{inspect(body)}"
+      end
+    end
+  end
+end
diff --git a/test/trinity_web/live/compaction_live_test.exs b/test/trinity_web/live/compaction_live_test.exs
index 7500ebd..7fd3773 100644
--- a/test/trinity_web/live/compaction_live_test.exs
+++ b/test/trinity_web/live/compaction_live_test.exs
@@ -6,7 +6,7 @@ defmodule TrinityWeb.CompactionLiveTest do
   @moduletag :capture_log
 
   import Phoenix.LiveViewTest
-  import Trinity.SessionCase, only: [script_deltas: 2, collect: 3, await_event: 3]
+  import Trinity.SessionCase, only: [script_deltas: 2, collect: 3]
 
   alias Trinity.Factory
   alias Trinity.LLM.Providers.Fake
diff --git a/test/trinity_web/live/session_live_test.exs b/test/trinity_web/live/session_live_test.exs
index 986e47d..ad06313 100644
--- a/test/trinity_web/live/session_live_test.exs
+++ b/test/trinity_web/live/session_live_test.exs
@@ -11,7 +11,7 @@ defmodule TrinityWeb.SessionLiveTest do
   @moduletag :capture_log
 
   import Phoenix.LiveViewTest
-  import Trinity.SessionCase, only: [script_deltas: 2, collect: 3, await_event: 3]
+  import Trinity.SessionCase, only: [script_deltas: 2, await_event: 3]
 
   alias Trinity.Factory
   alias Trinity.LLM.Providers.Fake