chore: import upstream snapshot with attribution

docs/install/air-gapped.md

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+# Enterprise / Air-Gapped Installation
+
+If your environment blocks access to PyPI or GitHub, you can create a portable wheel bundle on a connected machine and transfer it to the air-gapped target.
+
+## Step 1: Build the wheel on a connected machine
+
+> **Important:** `pip download` resolves platform-specific wheels (e.g., PyYAML includes native extensions). You must run this step on a machine with the **same OS and Python version** as the air-gapped target. If you need to support multiple platforms, repeat this step on each target OS (Linux, macOS, Windows) and Python version.
+
+```bash
+# Clone the repository
+git clone https://github.com/github/spec-kit.git
+cd spec-kit
+
+# Build the wheel
+pip install build
+python -m build --wheel --outdir dist/
+
+# Download the wheel and all its runtime dependencies
+pip download -d dist/ dist/specify_cli-*.whl
+```
+
+## Step 2: Transfer the `dist/` directory
+
+Copy the entire `dist/` directory (which contains the `specify-cli` wheel and all dependency wheels) to the target machine via USB, network share, or other approved transfer method.
+
+## Step 3: Install on the air-gapped machine
+
+```bash
+pip install --no-index --find-links=./dist specify-cli
+```
+
+## Step 4: Initialize a project
+
+No network access is required — bundled assets are used by default:
+
+```bash
+specify init my-project --integration copilot
+```
+
+> **Note:** Python 3.11+ is required.
+
+> **Windows note:** Offline scaffolding requires PowerShell 7+ (`pwsh`), not Windows PowerShell 5.x (`powershell.exe`). Install from https://aka.ms/powershell.
+
+## Git Credential Manager on Linux
+
+If you're having issues with Git authentication on Linux, you can install Git Credential Manager:
+
+```bash
+#!/usr/bin/env bash
+set -e
+echo "Downloading Git Credential Manager v2.6.1..."
+wget https://github.com/git-ecosystem/git-credential-manager/releases/download/v2.6.1/gcm-linux_amd64.2.6.1.deb
+echo "Installing Git Credential Manager..."
+sudo dpkg -i gcm-linux_amd64.2.6.1.deb
+echo "Configuring Git to use GCM..."
+git config --global credential.helper manager
+echo "Cleaning up..."
+rm gcm-linux_amd64.2.6.1.deb
+```

docs/install/one-time.md

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+# One-time Usage (uvx)
+
+If you want to try Spec Kit without installing it permanently, use `uvx` to run it directly. This downloads the tool into a temporary environment that is discarded after the command finishes.
+
+> [!NOTE]
+> The commands below require **[uv](https://docs.astral.sh/uv/)**. If you see `command not found: uvx`, [install uv first](uv.md).
+
+## Run Specify CLI
+
+```bash
+# Create a new project (latest from main)
+uvx --from git+https://github.com/github/spec-kit.git specify init <PROJECT_NAME>
+
+# Or target a specific release (replace vX.Y.Z with a tag from Releases)
+uvx --from git+https://github.com/github/spec-kit.git@vX.Y.Z specify init <PROJECT_NAME>
+
+# Initialize in the current directory
+uvx --from git+https://github.com/github/spec-kit.git specify init . --integration copilot
+
+# Or use the --here flag
+uvx --from git+https://github.com/github/spec-kit.git specify init --here --integration copilot
+```
+
+## When to use persistent installation instead
+
+If you plan to use Spec Kit regularly, a persistent installation is recommended:
+
+- Tool stays installed and available in PATH
+- No re-download on every invocation
+- Better tool management with `uv tool list`, `uv tool upgrade`, `uv tool uninstall`
+
+See the main [Installation Guide](../installation.md) for persistent installation instructions.

docs/install/pipx.md

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+# Installing with pipx
+
+[pipx](https://pipx.pypa.io/) is a tool for installing Python CLI applications in isolated environments. It does not require [uv](https://docs.astral.sh/uv/).
+
+## Install Specify CLI
+
+Pin a specific release tag for stability (check [Releases](https://github.com/github/spec-kit/releases) for the latest):
+
+```bash
+# Install a specific stable release (recommended — replace vX.Y.Z with the latest tag)
+pipx install git+https://github.com/github/spec-kit.git@vX.Y.Z
+
+# Or install latest from main (may include unreleased changes)
+pipx install git+https://github.com/github/spec-kit.git
+```
+
+## Verify
+
+```bash
+specify version
+```
+
+## Upgrade
+
+```bash
+pipx install --force git+https://github.com/github/spec-kit.git@vX.Y.Z
+```
+
+## Uninstall
+
+```bash
+pipx uninstall specify-cli
+```
+
+## Next steps
+
+Head to the [Quick Start](../quickstart.md) to initialize your first project.

docs/install/uv.md

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+# Installing uv
+
+[uv](https://docs.astral.sh/uv/) is a fast Python package manager by [Astral](https://astral.sh/). Spec Kit uses `uv` (via `uvx` or `uv tool install`) to run the `specify` CLI without polluting your global Python environment.
+
+> [!NOTE]
+> **Already have uv?** Run `uv --version` to confirm it is installed, then head back to the [Installation Guide](../installation.md).
+
+## Installation
+
+### macOS and Linux — Standalone Installer
+
+The quickest way to install uv on macOS or Linux is the official shell script:
+
+```bash
+curl -LsSf https://astral.sh/uv/install.sh | sh
+```
+
+After the script finishes, follow any instructions printed by the installer to add uv to your `PATH`, then open a new terminal.
+
+### Windows — Standalone Installer
+
+Run the following in **Command Prompt or PowerShell**:
+
+```powershell
+powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
+```
+
+After the script finishes, open a new terminal so the `uv` binary is on your `PATH`.
+
+### macOS — Homebrew
+
+```bash
+brew install uv
+```
+
+### Windows — WinGet
+
+```powershell
+winget install --id=astral-sh.uv -e
+```
+
+### Windows — Scoop
+
+```powershell
+scoop install uv
+```
+
+## Verification
+
+Confirm that uv is installed and on your `PATH`:
+
+```bash
+uv --version
+```
+
+You should see output similar to `uv 0.x.y (...)`.
+
+## Further Reading
+
+For advanced options (self-update, proxy settings, uninstall, etc.) see the official [uv installation docs](https://docs.astral.sh/uv/getting-started/installation/).