fix(install): preserve hooks and recover from installation failures

.github/workflows/test.yaml

@@ -21,6 +21,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Test installer regressions without network access
+        run: python3 -m unittest discover -s tests -v
+
       - name: Install Zsh and Fish on Ubuntu
         if: matrix.os == 'ubuntu-latest'
         run: |
@@ -36,7 +39,7 @@ jobs:
         run: |
           mkdir -p ~/.config/fish
           mkdir -p ~/.zsh
-          touch ~/.bashrc
+          touch ~/.bashrc ~/.zshrc ~/.config/fish/config.fish
 
       - name: Test install script in Zsh
         if: matrix.shell == 'zsh'
@@ -49,6 +52,10 @@ jobs:
           bash ./install.bash
         shell: fish {0}
 
+      - name: Test install script in Bash
+        if: matrix.shell == 'bash'
+        run: bash ./install.bash
+
       - name: Verify installation
         run: |
           if [ "${{ matrix.shell }}" = "zsh" ]; then

.gitignore

@@ -128,3 +128,6 @@ dist
 .yarn/build-state.yml
 .yarn/install-state.gz
 .pnp.*
+
+# Python installer regression tests
+__pycache__/

CLAUDE.md

@@ -16,7 +16,12 @@ This is the **shelltime installation** repository - a collection of shell script
 
 ## Testing
 
-Run the CI workflow locally or on GitHub Actions:
+Run the isolated regression suite with Python 3 (also run by CI):
+```bash
+python3 -m unittest discover -s tests -v
+```
+
+Run the shell installation workflow locally or on GitHub Actions:
 ```bash
 # The test workflow runs on ubuntu-latest and macos-latest
 # Testing shells: zsh, fish, bash

README.md

@@ -4,6 +4,12 @@ Welcome to shelltime! This guide will help you install the necessary tools using
 
 ## Quick Install
 
+The installer supports macOS and Linux (including WSL). A failed binary download
+stops installation. If a hook download fails, its existing hook and backup are
+preserved while the remaining hooks and daemon setup continue. The installer
+then exits with an error so you can retry. Upgrades migrate existing source lines
+without loading hooks twice.
+
 You can install shelltime tools by running the following command in your terminal:
 
 ```bash
@@ -16,6 +22,12 @@ Once the installation script finishes successfully, you should be able to track
 
 Visit [shelltime.xyz](https://shelltime.xyz) for guides and usage documentation.
 
+## Testing
+
+Run `python3 -m unittest discover -s tests` to check upgrades, download failures,
+paths containing spaces, and platform detection without network requests or
+changes to your shell configuration. CI runs these tests on Linux and macOS.
+
 ## Having Issues?
 
 If you encounter any problems during the installation or have any questions, please: