docs: sync README, CHANGELOG and docs with the current state

CHANGELOG.md

@@ -15,6 +15,14 @@ Unreleased changes on the `development` branch.
   and loong64 in addition to amd64.  Each architecture has its own ptrace
   register access, disassembler (`golang.org/x/arch`), register display,
   and stop-info handler.  The REPL is fully arch-neutral.
+- **Headless debugging.**  `gasm debug --script` runs REPL commands from a
+  file (or stdin) and exits; `--timeout` kills the debuggee when a run
+  hangs, with the watchdog armed before the ptrace attach.  `--cover` runs
+  to completion with a breakpoint on every label and reports which blocks
+  executed: label-level coverage for headless test runs.
+- **Conditional breakpoints.**  `break <label> if <reg> <op> <val>` now also
+  compares two registers (`break loop if RAX > RBX`), not only a register
+  against an immediate.
 - **JIT execution trampolines.**  `verify.Call` now works on all four
   architectures via hand-written assembly trampolines
   (`trampoline_{arm64,riscv64,loong64}.s`) that save the Go stack, switch
@@ -22,21 +30,67 @@ Unreleased changes on the `development` branch.
 - **Hardware watchpoints on all architectures.**  arm64 uses DBGWVR/DBGWCR
   via `PTRACE_SETREGSET` with `NT_ARM_HW_BREAK`; riscv64 and loong64 use
   `PTRACE_POKEUSER` to access trigger/debug registers.
+- **`gasm verify --args`.**  Scalar arguments (`name=value`, decimal or
+  `0x` hex) can now be supplied to a `--call` invocation alongside `--buf`
+  buffers, closing the gap where only buffers could be supplied.
+- **`gasm audit-instructions`.**  Black-box diff of the amd64 encoder
+  against the installed `go tool asm`: superset encodings (gasm-only,
+  shippable via `gasm asm --format goobj`), known-but-unencodable names
+  (the backlog) and go-only names (feature gaps).
+- **`gasm scaffold differential`.**  Prints a differential test skeleton
+  for every `// func` signature in a kernel file: random seed states, the
+  kernel call and a portable reference (`<name>Portable`), compared
+  byte-for-byte.
 - **LSP: find references** (`textDocument/references`).
 - **LSP: rename symbol** (`textDocument/rename`).
 - **LSP: document formatting** (`textDocument/formatting`) using the
   `format` package for canonical gofmt-style output.
-- **LSP: inlay hints** (`textDocument/inlayHint`) — frame size hints after
+- **LSP: inlay hints** (`textDocument/inlayHint`): frame size hints after
   the TEXT directive's argument area.
+- **LSP: workspace symbol search** (`workspace/symbol`): substring search
+  over the TEXT functions and GLOBL/DATA symbols of every open document.
+- **LSP: code actions.**  Quick fixes for `missing-ret` (insert the RET)
+  and `unused-label` (remove the label) diagnostics.
+- **LSP: signature help** (`textDocument/signatureHelp`): the callee's
+  `// func` signature while the cursor is on a `CALL`.
+- **LSP: document highlights**: every reference to the function or label
+  under the cursor is highlighted.
 - **Lint: `unused-label` rule.**  Flags labels that are defined but never
   referenced by any jump (Hint severity).
 - **Lint: `invalid-textflag` rule.**  Flags TEXT/GLOBL flags not in the
   known set from `textflag.h` (Warning severity).
 - **Lint: `stack-imbalance` rule.**  Tracks SP changes and flags if the
   net delta at RET does not match the declared frame size.
+- **Lint: `register-width-mismatch` rule.**  Flags amd64 operands whose
+  register width does not match the width the mnemonic suffix prescribes
+  (for example a 32-bit register in a `MOVQ`).
+- **Lint: `abi0-register-args` rule.**  Flags kernels whose `// func`
+  parameters are never read from the FP frame (for example arguments read
+  from registers instead), which pass every test today and break on a
+  toolchain upgrade.  Shipped with the Go assembler's operand-width model.
+- **Lint: `nonportable-register-name` rule.**  Flags the `RAX`/`EAX`-style
+  register aliases gasm accepts but `go tool asm` rejects, so files using
+  them only link through the gasm GOOBJ path.
+- **Lint: `unencodable-instruction` rule.**  Flags mnemonics the
+  architecture table knows but the encoder cannot yet emit, at edit time
+  instead of at assembly time.
 - **DWARF5 debug sections in ELF output.**  All four ELF emitters now emit
   `.debug_abbrev`, `.debug_info`, `.debug_line`, and `.debug_line_str`
-  sections, enabling `addr2line` and GDB/LLDB source-level debugging.
+  sections, enabling `addr2line` and GDB/LLDB source-level debugging, and
+  the amd64 emitter adds a `.debug_frame` CFI section for stack unwinding.
+- **amd64: legacy SSE and conversion coverage.**  The encoder now handles
+  the legacy (non-VEX) SSE packed binaries and immediate shuffles, the
+  legacy SSE integer instructions and `BSWAP`, the scalar and packed
+  double conversions (`CVTSS2SD`, `CVTSD2SS`, `CVTPS2PD`, `CVTPD2PS`) and
+  the prefetch hints.
+- **amd64: `VPCMP` and the full opmask set.**  The EVEX compare with an
+  opmask destination and the remaining opmask-register instructions are
+  encoded, byte for byte against the Go assembler.
+
+### Changed
+
+- **Parallel verify sweeps.**  The `-smoke` and `-abi` per-function checks
+  now run in parallel instead of sequentially.
 
 ### Fixed
 
@@ -48,6 +102,18 @@ Unreleased changes on the `development` branch.
   `AssembleFileLOONG64`, and `AssembleFileARM64` now mark external
   relocations and populate `img.Externals`, enabling cross-package symbol
   resolution in GOOBJ output.
+- **Subprocess-isolated smoke and ABI sweeps.**  A function that faults
+  during the `-smoke` or `-abi` sweep is reported without killing the
+  parent; each sweep runs in a child process.
+- **`BSF`, `BSR` and `POPCNT` encodings.**  Corrected to the bytes
+  `go tool asm` emits.
+- **`MOVQ` immediates.**  Compressed to the toolchain's imm32 forms.
+- **Frame adjustments of 128 to 255 bytes.**  Now use the imm8 `ADDQ`
+  stack adjustment.
+- **amd64 encoding parity.**  A broad pass aligned the remaining encoder
+  outputs and operand strictness with `go tool asm`.
+- **`gasm scaffold` parameter names.**  Shared parameter names and
+  two-sided seed sets in the generated skeleton are now correct.
 - **asm help text.**  Updated to list arm64 as a supported architecture.
 
 ## [0.31.1] — 2026-08-20