feat(rust-cli): wire alias expansion + update project documentation

Two changes in one commit:

1. **Alias expansion wired into both REPL loops** — The `AliasTable`
   had a fully-working `expand()` method (with POSIX trailing-space
   chaining support) that was never called from the execution pipeline.
   Now both `repl.rs::execute_line()` and
   `enhanced_repl.rs::execute_line()` call `state.aliases.expand()`
   before `parse_command()`, so `alias ll='ls -la'` followed by `ll`
   actually works. Per POSIX, alias expansion is interactive-only
   (scripts don't expand aliases), so the source/script paths are
   intentionally left unmodified.

2. **CLAUDE.md updated to reflect current state** — All sections
   rewritten to honestly report the post-session status:
   - "What Does NOT Work" updated (functions, scripts, tilde, IFS, trap
     all work now)
   - Test table updated (736 passing, with all new suites listed)
   - Codebase metrics updated (21k lines, 33 files)
   - Priorities updated (remaining gaps: word splitting in cmd args,
     ~user, alias in pipes, Echidna)
   - POSIX compliance notes updated (items 1-6 from old list are done)
   - Completion bumped from 72% to 78%

Test results: 736 passing, 0 failing, 14 ignored.

https://claude.ai/code/session_01EMHrh5Jq32pb98KXoSKLA4

Author: claude

CLAUDE.md

@@ -46,21 +46,19 @@ The Rust CLI is a functional interactive shell with these features:
 
 ### What Does NOT Work
 
-- NOT a full POSIX shell (functions, word splitting/$IFS, tilde expansion, script execution still missing)
+- NOT a full POSIX shell (word splitting in external command args, $IFS in all contexts, full function nesting still incomplete)
 - NOT formally verified end-to-end (Lean -> Rust is ~95% confidence via property testing, not proven)
 - NOT a replacement for bash/zsh in current state
 - No GDPR compliance (RMO/secure deletion are stubs)
 - No mechanized correspondence proof (property testing only)
-- No shell functions (`func() { ... }` syntax)
-- No shell script execution (`.sh` files)
 - Elixir NIF build broken (low priority)
 - BEAM daemon not implemented (planned, not built)
 
-### Test Results (2026-03-08, ALL PASSING — updated counts 2026-03-08)
+### Test Results (2026-04-20, ALL PASSING)
 
 | Suite | Count | Notes |
 |-------|-------|-------|
-| Unit tests (lib) | 277 | Core logic + control structures + tracked variables |
+| Unit tests (lib) | 310 | Core logic + control structures + tracked variables |
 | Correspondence | 28 | Lean 4 theorem validation |
 | Extended | 55 | Advanced features |
 | Integration | 35 | End-to-end |
@@ -69,14 +67,20 @@ The Rust CLI is a functional interactive shell with these features:
 | Parameter expansion | 67 | Variable/parameter tests |
 | Property correspondence | 15 | Property-based Lean validation |
 | Property | 28 | General property tests |
-| Security | 15 | Injection, traversal, validation |
-| Doctests | 52 | Inline examples |
-| **Total passing** | **602** | **0 failures** |
+| Security | 15 | Injection, traversal, validation (skips on root) |
+| Function/script | 24 | Function defs, scripts, trap/alias |
+| Function control flow | 8 | Control structures in function bodies |
+| IFS splitting | 8 | Word splitting in for-loops |
+| Multi-line scripts | 9 | Sourced scripts with multi-line control structures |
+| Tilde expansion | 9 | ~, ~/path, ~+, ~- |
+| Trap firing | 7 | Signal handler execution |
+| Doctests | 56 | Inline examples |
+| **Total passing** | **736** | **0 failures** |
 | Ignored (stress+1) | 14 | Run manually with `--ignored` |
 
 ### Codebase Metrics
 
-- 15,720 lines of Rust across 30 source files
+- ~21,000 lines of Rust across 33 source files
 - ~200+ formal theorems across 6 proof systems
 - 10 proof holes across 8 proof files (4 gaps, 4 axioms, 2 structural) — see `docs/PROOF_HOLES_AUDIT.md`
 
@@ -233,10 +237,10 @@ vsh::parser::expand_variables(&input, &state);
 
 ### Immediate Priorities
 
-1. **Shell functions** (`func() { ... }` syntax)
-2. **Shell script execution** (`.sh` files, shebang handling)
+1. **Word splitting in external command arguments** (requires quote-context threading)
+2. **Alias expansion in pipe segments** (currently only first command in a pipeline)
 3. **Echidna integration** for automated property-based verification
-4. **Fix git author** on future commits (currently `Test <test@example.com>`)
+4. **`~user` tilde expansion** (requires getpwnam/NSS lookup)
 
 ### This Week
 
@@ -303,18 +307,16 @@ PMPL-1.0-or-later (Palimpsest License)
 `docs/POSIX_COMPLIANCE.md` is now up-to-date. Milestones 1-9 complete, M10-11 partial.
 
 **Most critical missing POSIX features** (ranked by impact):
-1. Functions — no `func() { ... }` syntax — blocks modular scripts
-2. Shell script execution — no `.sh` file running
-3. Word splitting (`$IFS`) — unquoted variable expansions not split
-4. Tilde expansion — only works for `~/` in `cd` command
-5. `trap` — cannot handle signals in scripts
-6. `alias` — no command aliases
-7. SIGCHLD/Ctrl+Z — job control incomplete
+1. Word splitting in external command args — `cmd $var` doesn't split (requires quote-context)
+2. `~user` — only `~`, `~/`, `~+`, `~-` work (no getpwnam)
+3. SIGCHLD/Ctrl+Z — job control incomplete
+4. Here-string quoting edge cases
+5. Subshell `(...)` syntax — not implemented
 
 ---
 
-**Last Updated**: 2026-03-08 (P0-P9: SPDX, cp/mv/ln, controls, builtins, RSR, proofs, chmod/chown, docs, wow-factor, security audit)
+**Last Updated**: 2026-04-20 (function control-flow, multi-line scripts, tilde, IFS, trap, alias)
 **Version**: 0.9.0
 **Status**: Advanced research prototype — NOT production-ready
-**Tests**: 602 passing, 0 failures, 14 ignored
-**Completion**: ~72% (up from 65% at 2026-02-12 audit)
+**Tests**: 736 passing, 0 failures, 14 ignored
+**Completion**: ~78% (up from 72% at 2026-03-08)

impl/rust-cli/src/enhanced_repl.rs

@@ -366,8 +366,11 @@ fn execute_line(state: &mut ShellState, input: &str) -> Result<bool> {
         return Ok(true);
     }
 
+    // POSIX §2.3.1: Expand user-defined aliases before parsing.
+    let input_aliased = state.aliases.expand(input);
+
     // Parse command
-    let cmd = parser::parse_command(input)?;
+    let cmd = parser::parse_command(&input_aliased)?;
 
     // Execute command
     let result = cmd.execute(state)?;

impl/rust-cli/src/repl.rs

@@ -169,8 +169,11 @@ fn execute_line(state: &mut ShellState, input: &str) -> Result<bool> {
         _ => trimmed.to_string(),
     };
 
+    // POSIX §2.3.1: Expand user-defined aliases on the input before parsing.
+    let input_aliased = state.aliases.expand(&input_normalized);
+
     // Parse command using the parser
-    let cmd = parser::parse_command(&input_normalized)?;
+    let cmd = parser::parse_command(&input_aliased)?;
 
     // Execute command using trait (Seam 1↔2)
     let result = cmd.execute(state)?;