fix(rtk): rtk resolution + absolute-path rewrite — compression was silently dead

rtk lives at ~/.cargo/bin but the hand-managed .bashrc lost the cargo
line: command -v failed in hook AND tool shell, so the hook no-op'd with
a stderr warn on every Bash call — input compression silently OFF.

- Resolve RTK_BIN by probing known install dirs (LRN-036 class).
- Substitute the ABSOLUTE path at the rewrite head: a bare 'rtk …'
  exits 127 in the tool shell, whose PATH the hook cannot fix (proven).
- Compound rewrites carrying further bare rtk segments pass through
  unrewritten: quoted text (commit messages) makes a global substitution
  unsafe — lose compression, never emit a command that 127s (proven:
  a commit chain 127'd mid-flow).
- detect_rtk probes the same dirs so the banner reports capability.
- Re-pinned .rtk-hook.sha256: the rtk BINARY verifies the hook against
  it at execution time and refuses a modified hook — the pin is live
  machinery, not a vestige; coupling documented in the header.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016zA3Qh2Q1QpcGXzXxKeDHR

hooks/.rtk-hook.sha256

@@ -1 +1 @@
-ef0d630994fd7ef5f2b84fb66cd6249c493bb8736bcacd4734d7c798125018fb  rtk-rewrite.sh
+0f43229d17d03342d27c0b836b9b70f25f98dfb80a35ffc8dc2488034cb8719c  rtk-rewrite.sh

hooks/rtk-rewrite.sh

@@ -7,6 +7,10 @@
 # which is the single source of truth (src/discover/registry.rs).
 # To add or change rewrite rules, edit the Rust registry — not this file.
 #
+# INTEGRITY PIN: the rtk binary verifies this file against
+# hooks/.rtk-hook.sha256 at execution time and refuses to run on mismatch.
+# ANY edit here must re-pin:  (cd hooks && sha256sum rtk-rewrite.sh > .rtk-hook.sha256)
+#
 # Exit code protocol for `rtk rewrite`:
 #   0 + stdout  Rewrite found, no deny/ask rule matched → auto-allow
 #   1           No RTK equivalent → pass through unchanged
@@ -18,14 +22,27 @@ if ! command -v jq &>/dev/null; then
   exit 0
 fi
 
-if ! command -v rtk &>/dev/null; then
+# PATH heal: hook/tool-shell PATH may lack the cargo bin dir (hand-managed
+# ~/.bashrc can lose the cargo line — LRN-036 class). Resolve the ABSOLUTE
+# binary path: the rewritten command executes in the tool shell, whose PATH
+# the hook cannot fix — a bare `rtk …` rewrite would exit 127 there.
+RTK_BIN="$(command -v rtk 2>/dev/null || true)"
+RTK_ON_PATH=1
+if [ -z "$RTK_BIN" ]; then
+  RTK_ON_PATH=0
+  for _d in "$HOME/.cargo/bin" "$HOME/.local/bin"; do
+    if [ -x "$_d/rtk" ]; then RTK_BIN="$_d/rtk"; break; fi
+  done
+fi
+
+if [ -z "$RTK_BIN" ]; then
   echo "[rtk] WARNING: rtk is not installed or not in PATH. Hook cannot rewrite commands. Install: https://github.com/rtk-ai/rtk#installation" >&2
   exit 0
 fi
 
 # Version guard: rtk rewrite was added in 0.23.0.
 # Older binaries: warn once and exit cleanly (no silent failure).
-RTK_VERSION=$(rtk --version 2>/dev/null | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' | head -1)
+RTK_VERSION=$("$RTK_BIN" --version 2>/dev/null | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' | head -1)
 if [ -n "$RTK_VERSION" ]; then
   MAJOR=$(echo "$RTK_VERSION" | cut -d. -f1)
   MINOR=$(echo "$RTK_VERSION" | cut -d. -f2)
@@ -44,7 +61,7 @@ if [ -z "$CMD" ]; then
 fi
 
 # Delegate all rewrite + permission logic to the Rust binary.
-REWRITTEN=$(rtk rewrite "$CMD" 2>/dev/null)
+REWRITTEN=$("$RTK_BIN" rewrite "$CMD" 2>/dev/null)
 EXIT_CODE=$?
 
 case $EXIT_CODE in
@@ -70,6 +87,22 @@ case $EXIT_CODE in
     ;;
 esac
 
+# When rtk is NOT on PATH, a bare `rtk …` rewrite exits 127 in the tool
+# shell (whose PATH the hook cannot fix). Substitute the absolute path at
+# the string head — the only position safe to rewrite. Compound commands
+# (`a && b`) can carry further bare rtk segments we canNOT substitute
+# safely (quoted text, e.g. commit messages, may contain the same
+# pattern): if any remain at a command position, pass through unrewritten
+# — lose the compression, never emit a command that 127s.
+if [ "$RTK_ON_PATH" -eq 0 ]; then
+  case "$REWRITTEN" in
+    rtk\ *) REWRITTEN="$RTK_BIN ${REWRITTEN#rtk }" ;;
+  esac
+  if printf '%s' "$REWRITTEN" | grep -Eq '(^|[;&|][[:space:]]*)rtk[[:space:]]'; then
+    exit 0
+  fi
+fi
+
 ORIGINAL_INPUT=$(echo "$INPUT" | jq -c '.tool_input')
 UPDATED_INPUT=$(echo "$ORIGINAL_INPUT" | jq --arg cmd "$REWRITTEN" '.command = $cmd')
 

lib/detect-plugins.sh

@@ -10,7 +10,9 @@
 # --- Always-on plugins ---
 
 detect_rtk() {
-  command -v rtk &>/dev/null
+  command -v rtk &>/dev/null && return 0
+  # PATH heal: hook/session PATH may lack the cargo bin dir (LRN-036 class)
+  [ -x "$HOME/.cargo/bin/rtk" ] || [ -x "$HOME/.local/bin/rtk" ]
 }
 
 detect_superpowers() {