- Add control_flow.rs module with execution for if/while/for/case statements
- Add Statement::Script variant for multi-line scripts
- Fix grammar to reserve keywords (if, then, fi, while, do, done, for, in, case, esac)
- Fix bare_word_part to exclude semicolons
- Make NEWLINE silent to prevent parse tree pollution
- Update command_line grammar to support multiple commands
- Add keyword_boundary rule for proper keyword matching
- Update CLI to handle Statement::Script and execute all control flow types
- Add parser tests for if statements and multiline scripts

If statements are fully working. While/for/case loops need additional testing and fixes.

Add comprehensive test builtin with support for:
- String tests: -z (empty), -n (non-empty), = (equal), != (not equal)
- Numeric comparisons: -eq, -ne, -lt, -le, -gt, -ge
- File tests: -e (exists), -f (file), -d (directory), -r (readable), -w (writable), -x (executable), -s (has size)
- Logical operators: ! (negation), -a (and), -o (or)
- Both 'test' and '[' command aliases

Also fix grammar to allow '=' in bare words (needed for test expressions).

Grammar fix:
- Exclude & from bare_word_part to allow && and || operators to parse correctly

Executor implementation:
- Add execute_and_or_list function in pipeline.rs
- Implement short-circuit evaluation:
  - && executes next command only if previous succeeded (exit code 0)
  - || executes next command only if previous failed (exit code != 0)
- Export execute_and_or_list from lib.rs

CLI integration:
- Update execute_complete_command to handle AndOrList
- Remove TODO placeholder

Tests passing:
- echo first && echo second → first, second
- false || echo fallback → fallback
- false && echo not_shown || echo shown && echo also_shown → shown, also_shown

- Update execute_line to handle Statement::Complete(CompleteCommand)
- Add execute_complete_command dispatcher for all command types
- Maintain existing Simple and Pipeline execution
- Add TODO placeholders for control flow execution:
  - AndOrList (&&, ||)
  - If statements
  - While loops
  - For loops
  - Case statements
- Shell remains functional with existing features

Parser implementation:
- Rewrite parse_command_line to handle complete_command
- Add parse_complete_command dispatcher for all statement types
- Add parse_and_or_list for && and || operators
- Add parse_if_statement with elif_clause and else_clause support
- Add parse_while_statement for while loops
- Add parse_for_statement for for-in loops
- Add parse_case_statement with case_clause pattern matching
- Add parse_command_list for command sequences
- Update parse_pipeline to return Pipeline directly
- Update all 15 existing tests to use Statement::Complete(CompleteCommand)
- All tests passing

Library exports:
- Export all new AST types: CompleteCommand, AndOrList, AndOrOp, IfStatement,
  ElifClause, WhileStatement, ForStatement, CaseStatement, CaseClause, Pipeline, Redirect

Grammar additions:
- Add if/then/elif/else/fi statement syntax
- Add while/do/done loop syntax
- Add for/in/do/done loop syntax
- Add case/in/esac statement syntax with pattern matching
- Add && and || operators for command chaining
- Add complete_command, and_or_list, command_list rules
- Add separator rule for newlines and semicolons

AST additions:
- Add CompleteCommand enum with 7 variants (Simple, Pipeline, AndOrList, If, While, For, Case)
- Add IfStatement with condition, then_body, elif_clauses, else_body
- Add WhileStatement with condition and body
- Add ForStatement with var_name, words, and body
- Add CaseStatement with word and clauses
- Add AndOrList with first pipeline and rest (op, pipeline) pairs
- Add helper structures: ElifClause, CaseClause, AndOrOp enum
- Update Statement enum to use Complete(CompleteCommand)

- Simplify execute_line() to use new executor functions
  - Use execute_simple_with_redirects() for simple commands
  - Use execute_pipeline() for multi-command pipelines
- Handle Statement::Pipeline variant
- Remove manual assignment processing (now in executor)
- Maintain proper exit status tracking for both command types

- Add redirect.rs module for handling all I/O redirections
  - Implement apply_redirects() to configure Command stdio
  - Support input (<), output (>), append (>>), stderr (2>), and combined (&>) redirects
  - Proper file expansion and error handling
- Add pipeline.rs module for executing command pipelines
  - Create pipes between commands using Stdio::piped()
  - Chain stdout of each command to stdin of next
  - Wait for all processes and return last exit status
  - Implement execute_simple_with_redirects() for unified command execution
- Update command.rs to expose helper functions
  - Make find_in_path, execute_builtin, success_result public(crate)
- Add rush-expand dependency to rush-executor

- Implement parse_pipeline() to handle multiple piped commands
- Implement parse_redirect() for all redirect types
- Update parse_command_line() to handle pipeline syntax
- Update parse_simple_command() to capture redirects
- Add comprehensive tests for pipelines (simple, three-command)
- Add tests for all redirect types (input, output, append, stderr, combined)
- All 15 parser tests passing

- Add pipeline syntax: cmd1 | cmd2 | cmd3
- Add redirect operators: <, >, >>, 2>, 2>&1, &>, &>>
- Add Pipeline struct to AST with commands vector
- Add Redirect enum with 5 variants (Input, Output, OutputAppend, StderrToStdout, AllOutput)
- Extend SimpleCommand to include redirects field
- Add Statement::Pipeline variant
- Update simple_command grammar to support interleaved redirects

- add Context to all execution modes
- update execute_line to handle assignments and expansion
  - process variable assignments before command
  - expand all words (variables, command substitution)
  - track exit status in context
- persist Context across commands in REPL
- maintain separate Context per execution mode

Working features:
- variable assignment: FOO=bar
- variable expansion: $FOO, ${FOO}
- command substitution: $(pwd)
- quoted strings with expansion: "Hello $NAME"
- assignments persist across commands in same session

- add execute_command_substitution() function
- execute commands via sh -c (for now)
- trim trailing newlines (bash behavior)
- integrate with expand_word()
- add tests for command substitution
- 16 tests passing total

- move Context from rush-eval to rush-expand (avoid circular deps)
- implement expand_word() for all expansion types:
  - literal text
  - variable expansion ($VAR, ${VAR})
  - default values (${VAR:-default})
- implement expand_words() for multiple words
- add Context for variable storage:
  - local and exported variables
  - environment variable initialization
  - exit status tracking
- 10 passing tests for expansion and context

- extend Pest grammar for variable syntax
  - variable assignments: VAR=value
  - variable expansion: $VAR, ${VAR}, ${VAR:-default}
  - command substitution: $(cmd)
  - double-quoted strings with expansions
- update AST to support:
  - Assignment type
  - Word composed of multiple WordParts
  - VarExpansion types (Simple, Braced, WithDefault)
  - CommandSubstitution
- rewrite parser for new grammar
  - explicit whitespace handling to prevent word merging
  - proper separation of assignments and words
- add comprehensive tests for new features

- remove docs/ from gitignore (now tracked)
- add CLAUDE.md to gitignore

- rush-eval: control flow evaluation
- rush-expand: variable and glob expansion
- rush-interactive: fish-like features
- rush-job: job control

- add command-line argument parsing with clap
- implement interactive mode with reedline REPL
- implement non-interactive modes:
  - command string (-c flag)
  - script file execution
  - stdin execution
- set up signal handlers on startup
- detect terminal vs stdin for mode selection

- implement process group management for child processes
- add signal handling (SIGINT, SIGTSTP, SIGTTOU)
- give foreground processes terminal control
- properly wait for child processes with WUNTRACED
- handle stopped processes (Ctrl+Z)
- restore terminal control to shell after command

- execute external commands with PATH resolution
- implement built-in commands (cd, pwd, exit)
- handle execution errors
- add tests for command execution

- add PEG grammar for simple commands
- define AST types (Statement, SimpleCommand)
- implement parser with quoted string support
- add unit tests for parsing

- create Cargo workspace with 7 crates
- configure workspace dependencies (pest, reedline, nix, etc)
- configure gitignore