fix: shellcheck errors in start.sh; add code-quality CI workflow

.github/workflows/CODE_QUALITY.md

@@ -0,0 +1,51 @@
+# Code Quality Workflow
+
+## What it does
+
+Lints Markdown files and shell scripts on every pull request to `main`. Also runnable manually via `workflow_dispatch`.
+
+## When it runs
+
+- Pull requests to `main` (opened, reopened, or synchronized) when any of the following paths change:
+  - `**/*.md`
+  - `**/.markdownlint*`
+  - `*.sh`
+  - `.github/workflows/code-quality.yml`
+- Manual trigger via the GitHub Actions UI
+
+## Markdown linting
+
+**Tool:** [`DavidAnson/markdownlint-cli2-action`](https://github.com/DavidAnson/markdownlint-cli2-action)
+
+**Config file:** `.markdownlint-cli2.jsonc` (max line length 240, allowed inline HTML, excludes `CLAUDE.md` and `.github/copilot-instructions.md`)
+
+**Run locally:**
+
+```sh
+markdownlint-cli2 '**/*.md'
+```
+
+## Shell script linting
+
+**Tool:** [`reviewdog/action-shellcheck`](https://github.com/reviewdog/action-shellcheck) — posts inline PR review comments via `github-pr-review` reporter.
+
+**Run locally:**
+
+```sh
+shellcheck start.sh stop.sh reset_env_variables.sh
+```
+
+**`.shellcheckrc` suppressions** (project-wide):
+
+| Rule | Reason |
+| --- | --- |
+| `SC1091` | Not following sourced files (`reset_env_variables.sh`) |
+| `SC2153` | False positives on variable name misspelling |
+| `SC2317` | False positive on unreachable commands in trap/signal handlers |
+
+## Adding new checks
+
+1. Add a "Get changed files" step using `tj-actions/changed-files@v47` scoped to the relevant paths.
+2. Add a "Should lint X" step that writes the `any_changed` output to `$GITHUB_OUTPUT`.
+3. Add the lint step gated on `if: steps.should_lint_x.outputs.run == 'true'`.
+4. Update the paths filter under `on.pull_request.paths` to include the new file patterns.

.github/workflows/code-quality.yml

@@ -0,0 +1,71 @@
+name: Code Quality
+on:
+  pull_request:
+    branches: [main]
+    types: [opened, reopened, synchronize]
+    paths:
+      - '**/*.md'
+      - '**/.markdownlint*'
+      - '*.sh'
+      - '.github/workflows/code-quality.yml'
+  workflow_dispatch:
+jobs:
+  quality:
+    name: Lint and test
+    timeout-minutes: 15
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+          submodules: false
+
+      - name: Get changed markdown files
+        id: changed_md
+        uses: tj-actions/changed-files@v47
+        with:
+          files: |
+            **/*.md
+
+      - name: Get changed shell scripts
+        id: changed_sh
+        uses: tj-actions/changed-files@v47
+        with:
+          files: |
+            *.sh
+
+      - name: Should lint docs
+        id: should_lint_docs
+        shell: bash
+        run: |
+          run=${{ steps.changed_md.outputs.any_changed }}
+          echo "run=${run}" >> $GITHUB_OUTPUT
+
+      - name: Should lint shell
+        id: should_lint_shell
+        shell: bash
+        run: |
+          run=${{ steps.changed_sh.outputs.any_changed }}
+          echo "run=${run}" >> $GITHUB_OUTPUT
+
+      - name: Lint markdown
+        if: steps.should_lint_docs.outputs.run == 'true'
+        uses: DavidAnson/markdownlint-cli2-action@v22
+        with:
+          globs: '**/*.md'
+
+      - name: Lint shell scripts
+        if: steps.should_lint_shell.outputs.run == 'true'
+        uses: reviewdog/action-shellcheck@v1
+        with:
+          reporter: github-pr-review
+          fail_on_error: true
+          path: '.'
+          pattern: '*.sh'
+          exclude: './.git/*'
+
+      - name: Default Job Success
+        if: steps.should_lint_docs.outputs.run != 'true' && steps.should_lint_shell.outputs.run != 'true'
+        shell: bash
+        run: exit 0

.tool-versions

@@ -1 +1,2 @@
 markdownlint-cli2 0.21.0
+shellcheck 0.11.0

README.md

@@ -118,3 +118,7 @@ Example usage:
 ### Linting
 
 See [LINTING.md](./documentation/LINTING.md)
+
+## Other Documentation
+
+See [documentation](./documentation/)

documentation/CICD.md

@@ -0,0 +1,3 @@
+# Ci/Cd
+
+See [CODE_QUALITY.md](../.github/workflows/CODE_QUALITY.md)

documentation/LINTING.md

@@ -6,18 +6,45 @@
 
   - Markdownlint must be installed as an extension (extension id: `DavidAnson.vscode-markdownlint`) for local markdown linting to work within VS Code or Cursor on save.
   - Or run in directly using [markdownlint-cli2](https://github.com/DavidAnson/markdownlint-cli2).
-  - `markdownlint-cli2` is included in the asdf tool versions file.
+  - `markdownlint-cli2` is included in the asdf [`.tool-versions`](../.tool-versions) file.
     See <https://github.com/paulo-ferraz-oliveira/asdf-markdownlint-cli2>.
 
     ```sh
     markdownlint-cli2 '**/*.md'
     ```
 
+- [ShellCheck](https://github.com/koalaman/shellcheck) `timonwong.shellcheck`
+
+  - ShellCheck must be installed as an extension (extension id: `timonwong.shellcheck`) for local shell script linting to work within VS Code or Cursor on save.
+  - Or run it directly using the [ShellCheck CLI](https://github.com/koalaman/shellcheck#installing).
+  - `shellcheck` is included in the asdf [`.tool-versions`](../.tool-versions) file.
+
+    ```sh
+    shellcheck *.sh
+    ```
+
 ## Configuration
 
+### Markdown
+
 MarkdownLint uses [`.markdownlint-cli2.jsonc`](../..markdownlint-cli2.jsonc) to configure the markdown linting rules and to ignore linting for specific files and paths.
 See <https://github.com/DavidAnson/markdownlint-cli2/tree/main?tab=readme-ov-file#markdownlint-cli2jsonc>
 
+### Shell
+
+ShellCheck uses [`.shellcheckrc`](../.shellcheckrc) to configure linting rules.
+The following rules are disabled project-wide:
+
+| Rule | Reason |
+| --- | --- |
+| `SC1091` | Suppresses "not following" warnings for sourced files (e.g. `reset_env_variables.sh`) |
+| `SC2153` | Suppresses false-positive variable name misspelling warnings |
+| `SC2317` | Suppresses unreachable-command false positives in trap/signal handlers |
+
+`external-sources=true` is also set to allow ShellCheck to follow sourced files when they are available.
+
+See <https://github.com/koalaman/shellcheck/wiki/Checks>
+
 ## Continuous Integration
 
 Linting is automatically run in CI/CD via the [Code Quality workflow](../.github/workflows/code-quality.yml) on pull requests to `main`.

start.sh

@@ -91,7 +91,7 @@ function start() {
         # Cursor invisible
         tput civis
         while sleep 0.1; do
-            i=$(((i + $charwidth) % ${#char}))
+            i=$(((i + charwidth) % ${#char}))
             printf "%s" "${char:$i:$charwidth}"
             echo -en "\033[1D"
         done
@@ -120,7 +120,7 @@ function start() {
     function check_status() {
         local max_num_tries=35
         local status_code
-        status_code=$(curl --write-out %{http_code} --silent --output /dev/null localhost:"${pga_port}")
+        status_code=$(curl --write-out '%{http_code}' --silent --output /dev/null localhost:"${pga_port}")
         if [[ ${iterator} -lt ${max_num_tries} && ${status_code} -eq 200 || ${status_code} -eq 302 ]]
         then
             # Stop the progress indicator.
@@ -140,7 +140,7 @@ function start() {
             tput cnorm
             >&2 echo -e "${yellow}Did not work. Perhaps the server is taking a long time to start?${nc}"
         else
-            echo -en "${chars:$iterator:1}" "\r"
+            echo -en "${char:$iterator:1}" "\r"
             sleep 1
             ((iterator++))
             check_status