diff --git a/.github/workflows/colour-demo.yml b/.github/workflows/colour-demo.yml
deleted file mode 100644
index 3963d71b..00000000
--- a/.github/workflows/colour-demo.yml
+++ /dev/null
@@ -1,268 +0,0 @@
-# Demonstration workflow for #506 / #622. Builds the CLI at three points in
-# history and prints `octopus --help` under a matrix of colour environment
-# variables, so the behaviour can be seen in a real CI log rather than described.
-#
-# GitHub Actions renders ANSI colour in logs but does not attach a TTY, which is
-# exactly the situation #506 is about. The second job re-runs the cases that only
-# apply to a terminal under a pty allocated with `script`.
-#
-# This is a demo, not part of the build. It only runs on this branch and on
-# manual dispatch, and can be deleted before merge.
-name: Colour output demo (#506)
-
-on:
-  workflow_dispatch:
-  push:
-    branches: [nj/fix-506]
-
-env:
-  # The commit the reviewer tested: the PR before the FORCE_COLOR=0 fix.
-  PR_V1_SHA: ab6d3b5f2dd2d5ebaa4d16a8408ab18085e61516
-
-jobs:
-  build:
-    name: Build the three binaries
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v5
-        with:
-          fetch-depth: 0
-
-      - name: Set up Go
-        uses: actions/setup-go@v6
-        with:
-          go-version-file: go.mod
-
-      - name: Build main (before the PR)
-        run: |
-          git worktree add /tmp/src-main origin/main
-          cd /tmp/src-main && go build -o /tmp/octopus-main ./cmd/octopus
-
-      - name: Build the PR as reviewed
-        run: |
-          git worktree add /tmp/src-pr-v1 "$PR_V1_SHA"
-          cd /tmp/src-pr-v1 && go build -o /tmp/octopus-pr-v1 ./cmd/octopus
-
-      - name: Build the PR with the review fix
-        run: go build -o /tmp/octopus-pr-v2 ./cmd/octopus
-
-      - uses: actions/upload-artifact@v4
-        with:
-          name: binaries
-          path: /tmp/octopus-*
-          retention-days: 1
-
-  no-tty:
-    name: 'Issue #506: colour in CI (no TTY)'
-    needs: build
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/download-artifact@v4
-        with:
-          name: binaries
-          path: /tmp
-      - run: chmod +x /tmp/octopus-*
-
-      # Look at the logo in each step below. Cyan means colour is on.
-
-      - name: 'BEFORE (main) — no env vars — plain, correct'
-        run: /tmp/octopus-main --help | head -22
-
-      - name: 'BEFORE (main) — FORCE_COLOR=1 — still plain, THIS IS THE BUG'
-        env:
-          FORCE_COLOR: '1'
-        run: /tmp/octopus-main --help | head -22
-
-      # GitHub's log viewer resets SGR state at every line break. The PR as
-      # reviewed wrapped the whole logo in one escape, so the codes were present
-      # but nothing rendered. Compare the next two steps.
-      - name: 'AS REVIEWED — FORCE_COLOR=1 — escapes emitted, but renders white here'
-        env:
-          FORCE_COLOR: '1'
-        run: /tmp/octopus-pr-v1 --help | head -22
-
-      - name: 'AFTER (PR) — no env vars — plain, deliberately unchanged'
-        run: /tmp/octopus-pr-v2 --help | head -22
-
-      - name: 'AFTER (PR) — FORCE_COLOR=1 — cyan, THIS IS THE FIX'
-        env:
-          FORCE_COLOR: '1'
-        run: /tmp/octopus-pr-v2 --help | head -22
-
-      - name: 'AFTER (PR) — CLICOLOR_FORCE=1 — cyan, equivalent opt-in'
-        env:
-          CLICOLOR_FORCE: '1'
-        run: /tmp/octopus-pr-v2 --help | head -22
-
-      - name: 'AFTER (PR) — FORCE_COLOR=1 + NO_COLOR=1 — plain, NO_COLOR wins'
-        env:
-          FORCE_COLOR: '1'
-          NO_COLOR: '1'
-        run: /tmp/octopus-pr-v2 --help | head -22
-
-      # The step above is only convincing if the colour is actually per line, so
-      # check that rather than trusting the screenshot.
-      - name: 'Assert the logo is coloured line by line'
-        env:
-          FORCE_COLOR: '1'
-        run: |
-          esc=$'\033['
-          for label in pr-v1 pr-v2; do
-            total=$(/tmp/octopus-$label --help | grep -cF '####')
-            bare=$(/tmp/octopus-$label --help | grep -F '####' | grep -cvF "$esc" || true)
-            echo "$label: $total logo lines, $bare without an escape of their own"
-          done
-
-          bare=$(/tmp/octopus-pr-v2 --help | grep -F '####' | grep -cvF "$esc" || true)
-          if [ "$bare" -ne 0 ]; then
-            echo "::error::$bare logo lines carry no escape; they will render plain in this log"
-            exit 1
-          fi
-
-      - name: Assert and summarise
-        run: |
-          esc=$'\033['
-          fail=0
-
-          # colour_of <binary> [VAR=VALUE ...] -> "colour" | "plain"
-          colour_of() {
-            local bin="$1"; shift
-            if env "$@" "$bin" --help 2>&1 | grep -qF "$esc"; then
-              echo colour
-            else
-              echo plain
-            fi
-          }
-
-          # expect <expected> <label> <binary> [VAR=VALUE ...]
-          expect() {
-            local want="$1" label="$2"; shift 2
-            local got
-            got=$(colour_of "$@")
-            if [ "$got" = "$want" ]; then
-              echo "  ok   $label -> $got"
-            else
-              echo "  FAIL $label -> $got (expected $want)"
-              fail=1
-            fi
-          }
-
-          expect plain  'main, no env vars'                 /tmp/octopus-main
-          expect plain  'main, FORCE_COLOR=1 (bug #506)'    /tmp/octopus-main   FORCE_COLOR=1
-          expect plain  'PR, no env vars'                   /tmp/octopus-pr-v2
-          expect colour 'PR, FORCE_COLOR=1'                 /tmp/octopus-pr-v2  FORCE_COLOR=1
-          expect colour 'PR, CLICOLOR_FORCE=1'              /tmp/octopus-pr-v2  CLICOLOR_FORCE=1
-          expect plain  'PR, FORCE_COLOR=0'                 /tmp/octopus-pr-v2  FORCE_COLOR=0
-          expect plain  'PR, FORCE_COLOR=1 + NO_COLOR=1'    /tmp/octopus-pr-v2  FORCE_COLOR=1 NO_COLOR=1
-
-          {
-            echo '## Colour in CI (no TTY) — issue #506'
-            echo
-            echo '| environment | `main` | this PR |'
-            echo '|---|---|---|'
-            echo "| _(none)_ | $(colour_of /tmp/octopus-main) | $(colour_of /tmp/octopus-pr-v2) |"
-            echo "| \`FORCE_COLOR=1\` | **$(colour_of /tmp/octopus-main FORCE_COLOR=1)** :point_left: the bug | **$(colour_of /tmp/octopus-pr-v2 FORCE_COLOR=1)** :point_left: the fix |"
-            echo "| \`CLICOLOR_FORCE=1\` | $(colour_of /tmp/octopus-main CLICOLOR_FORCE=1) | $(colour_of /tmp/octopus-pr-v2 CLICOLOR_FORCE=1) |"
-            echo "| \`FORCE_COLOR=0\` | $(colour_of /tmp/octopus-main FORCE_COLOR=0) | $(colour_of /tmp/octopus-pr-v2 FORCE_COLOR=0) |"
-            echo "| \`NO_COLOR=1\` + \`FORCE_COLOR=1\` | $(colour_of /tmp/octopus-main NO_COLOR=1 FORCE_COLOR=1) | $(colour_of /tmp/octopus-pr-v2 NO_COLOR=1 FORCE_COLOR=1) |"
-            echo
-            echo 'Default behaviour is unchanged: CI output stays plain unless you opt in.'
-            echo
-            echo 'This log viewer resets colour at every line break, so colour has to be'
-            echo 'emitted per line to render. Logo lines carrying their own escape:'
-            echo
-            echo '| build | logo lines tinted |'
-            echo '|---|---|'
-            for label in pr-v1 pr-v2; do
-              total=$(FORCE_COLOR=1 /tmp/octopus-$label --help | grep -cF '####')
-              bare=$(FORCE_COLOR=1 /tmp/octopus-$label --help | grep -F '####' | grep -cvF "$esc" || true)
-              echo "| \`$label\` | $((total - bare)) of $total |"
-            done
-          } >> "$GITHUB_STEP_SUMMARY"
-
-          exit $fail
-
-  tty:
-    name: 'Review comment: turning colour off in a terminal'
-    needs: build
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/download-artifact@v4
-        with:
-          name: binaries
-          path: /tmp
-      - run: chmod +x /tmp/octopus-*
-
-      # `script` allocates a pty, so terminal detection reports true. This is the
-      # situation the review comment describes, which CI cannot otherwise reach.
-
-      - name: 'IN A TERMINAL — PR as reviewed, no env vars — cyan, correct'
-        run: script -qec '/tmp/octopus-pr-v1 --help' /dev/null | head -22
-
-      - name: 'IN A TERMINAL — PR as reviewed, FORCE_COLOR=0 — still cyan, THE REPORTED BUG'
-        env:
-          FORCE_COLOR: '0'
-        run: script -qec '/tmp/octopus-pr-v1 --help' /dev/null | head -22
-
-      - name: 'IN A TERMINAL — with review fix, FORCE_COLOR=0 — plain, FIXED'
-        env:
-          FORCE_COLOR: '0'
-        run: script -qec '/tmp/octopus-pr-v2 --help' /dev/null | head -22
-
-      - name: 'IN A TERMINAL — with review fix, CLICOLOR=0 — plain, FIXED'
-        env:
-          CLICOLOR: '0'
-        run: script -qec '/tmp/octopus-pr-v2 --help' /dev/null | head -22
-
-      - name: 'IN A TERMINAL — with review fix, no env vars — cyan, unchanged'
-        run: script -qec '/tmp/octopus-pr-v2 --help' /dev/null | head -22
-
-      - name: Assert and summarise
-        run: |
-          esc=$'\033['
-          fail=0
-
-          colour_of() {
-            local bin="$1"; shift
-            if env "$@" script -qec "$bin --help" /dev/null 2>&1 | grep -qF "$esc"; then
-              echo colour
-            else
-              echo plain
-            fi
-          }
-
-          expect() {
-            local want="$1" label="$2"; shift 2
-            local got
-            got=$(colour_of "$@")
-            if [ "$got" = "$want" ]; then
-              echo "  ok   $label -> $got"
-            else
-              echo "  FAIL $label -> $got (expected $want)"
-              fail=1
-            fi
-          }
-
-          expect colour 'as reviewed, no env vars'          /tmp/octopus-pr-v1
-          expect colour 'as reviewed, FORCE_COLOR=0 (bug)'  /tmp/octopus-pr-v1  FORCE_COLOR=0
-          expect colour 'with fix, no env vars'             /tmp/octopus-pr-v2
-          expect plain  'with fix, FORCE_COLOR=0'           /tmp/octopus-pr-v2  FORCE_COLOR=0
-          expect plain  'with fix, CLICOLOR_FORCE=0'        /tmp/octopus-pr-v2  CLICOLOR_FORCE=0
-          expect plain  'with fix, CLICOLOR=0'              /tmp/octopus-pr-v2  CLICOLOR=0
-          expect plain  'with fix, NO_COLOR=1'              /tmp/octopus-pr-v2  NO_COLOR=1
-
-          {
-            echo '## Turning colour off in a terminal — the review comment'
-            echo
-            echo 'Run under a pty, so terminal detection reports true.'
-            echo
-            echo '| environment | PR as reviewed | with review fix |'
-            echo '|---|---|---|'
-            echo "| _(none)_ | $(colour_of /tmp/octopus-pr-v1) | $(colour_of /tmp/octopus-pr-v2) |"
-            echo "| \`FORCE_COLOR=0\` | **$(colour_of /tmp/octopus-pr-v1 FORCE_COLOR=0)** :point_left: the reported bug | **$(colour_of /tmp/octopus-pr-v2 FORCE_COLOR=0)** |"
-            echo "| \`CLICOLOR_FORCE=0\` | $(colour_of /tmp/octopus-pr-v1 CLICOLOR_FORCE=0) | $(colour_of /tmp/octopus-pr-v2 CLICOLOR_FORCE=0) |"
-            echo "| \`CLICOLOR=0\` | $(colour_of /tmp/octopus-pr-v1 CLICOLOR=0) | $(colour_of /tmp/octopus-pr-v2 CLICOLOR=0) |"
-            echo "| \`NO_COLOR=1\` | $(colour_of /tmp/octopus-pr-v1 NO_COLOR=1) | $(colour_of /tmp/octopus-pr-v2 NO_COLOR=1) |"
-          } >> "$GITHUB_STEP_SUMMARY"
-
-          exit $fail