install: stop persisting KIGI_GRAPH — the binary default is the product default

The README always shipped graph engineering enabled; the enablement was
delegated to installer env plumbing that diverged per platform:
install.sh exported KIGI_GRAPH=1 into shell rc (worked), install.ps1
wrote the User registry variable — which running Windows terminals (and
new tabs of an open Windows Terminal) never pick up, so /graph was
'missing on Windows' despite a successful install.

With resolve_graph() defaulting true in the binary (e53a66d), the env
writes are redundant complexity: drop them from both installers, keep
KIGI_GRAPH=0 as the documented opt-out (env still beats the default),
and correct the flag comment to tell this story instead of a
'gray release' one. Both scripts syntax-checked (sh -n / pwsh parser).

Installers are served from main (raw.githubusercontent), so this takes
effect for all new installs immediately — no retag needed; the running
v0.1.5 build already carries the binary-default fix.

crates/codegen/kigi-shell/src/agent/config.rs

@@ -1881,12 +1881,15 @@ impl Config {
             .default(true)
             .resolve()
     }
-    /// Graph mode (`/graph`) master switch. Default ON — the gray release
-    /// (plan.md G0, `KIGI_GRAPH=1` only) is over; every install gets the
-    /// same commands (its absence on non-dev machines read as a platform
-    /// bug). `KIGI_GRAPH=0` remains the off-switch. Graph mode additionally
-    /// requires the goal harness (nodes execute as goals), enforced at
-    /// availability time, not here.
+    /// Graph mode (`/graph`) master switch. Default ON in the binary: the
+    /// README ships graph engineering enabled for every install, but the
+    /// old `default(false)` delegated enablement to installer env plumbing
+    /// (`install.sh` shell-rc export vs `install.ps1` registry write) — and
+    /// Windows terminals don't pick up freshly-written registry env, so
+    /// `/graph` went "missing on Windows". The product default lives HERE,
+    /// not in installers. `KIGI_GRAPH=0` is the off-switch. Graph mode
+    /// additionally requires the goal harness (nodes execute as goals),
+    /// enforced at availability time, not here.
     pub(crate) fn resolve_graph(&self) -> Resolved<bool> {
         BoolFlag::env("KIGI_GRAPH").default(true).resolve()
     }

install.ps1

@@ -149,15 +149,13 @@ try {
         Write-Host "Run 'kigi' to get started."
     }
 
-    # Graph engineering ships enabled by default. Respect an explicit
-    # user choice: only set the variable when it is not already defined
-    # (so a persisted opt-out of "0" survives reinstalls).
-    $Graph = [Environment]::GetEnvironmentVariable("KIGI_GRAPH", "User")
-    if ($null -eq $Graph -or $Graph -eq "") {
-        [Environment]::SetEnvironmentVariable("KIGI_GRAPH", "1", "User")
-        Write-Host "Enabled graph engineering (KIGI_GRAPH=1)."
-        Write-Host "Disable: [Environment]::SetEnvironmentVariable('KIGI_GRAPH','0','User')"
-    }
+    # Graph engineering is enabled by default IN THE BINARY (resolve_graph
+    # defaults true) — no environment plumbing needed. The installer used
+    # to persist KIGI_GRAPH=1 into the User registry env, but running
+    # terminals (and new tabs of an open Windows Terminal) never pick up
+    # freshly-written registry variables, which made /graph "missing on
+    # Windows" while the shell-rc path worked on macOS/Linux. Opt out any
+    # time with: [Environment]::SetEnvironmentVariable('KIGI_GRAPH','0','User')
 } finally {
     Remove-Item -Path $TmpDir -Recurse -Force -ErrorAction SilentlyContinue
 }

install.sh

@@ -209,7 +209,6 @@ case "${SHELL:-}" in
     */zsh)
         RC_FILE="${ZDOTDIR:-$HOME}/.zshrc"
         PATH_LINE="export PATH=\"$BIN_DIR:\$PATH\""
-        GRAPH_LINE="export KIGI_GRAPH=1"
         ;;
     */bash)
         # macOS login shells read ~/.bash_profile; Linux reads ~/.bashrc.
@@ -219,7 +218,6 @@ case "${SHELL:-}" in
             RC_FILE="$HOME/.bashrc"
         fi
         PATH_LINE="export PATH=\"$BIN_DIR:\$PATH\""
-        GRAPH_LINE="export KIGI_GRAPH=1"
         ;;
     */fish)
         # fish_add_path in config.fish is fish's own idempotent way
@@ -228,12 +226,10 @@ case "${SHELL:-}" in
         mkdir -p "$FISH_CONF_DIR"
         RC_FILE="$FISH_CONF_DIR/config.fish"
         PATH_LINE="fish_add_path $BIN_DIR"
-        GRAPH_LINE="set -gx KIGI_GRAPH 1"
         ;;
     *)
         RC_FILE="$HOME/.profile"
         PATH_LINE="export PATH=\"$BIN_DIR:\$PATH\""
-        GRAPH_LINE="export KIGI_GRAPH=1"
         ;;
 esac
 
@@ -247,8 +243,8 @@ case ":$PATH:" in
         ;;
 esac
 
-# Graph engineering ships enabled by default. The KIGI_GRAPH guard makes
-# this idempotent AND respects an explicit user opt-out (an existing
-# `export KIGI_GRAPH=0` line is left untouched). Disable any time with:
+# Graph engineering is enabled by default IN THE BINARY (resolve_graph
+# defaults true) — the installer no longer writes KIGI_GRAPH=1 into shell
+# rc files (per-shell env plumbing was fragile and diverged per platform).
+# Disable any time with:
 #   echo 'export KIGI_GRAPH=0' >> <your shell rc>
-persist_line "$RC_FILE" "$GRAPH_LINE" "KIGI_GRAPH" "graph engineering (KIGI_GRAPH=1)"