diff --git a/graph/decisions/decision-fish-configfish-exports-shellbinbash-for-tool-compa-acfad6.md b/graph/decisions/decision-fish-configfish-exports-shellbinbash-for-tool-compa-acfad6.md
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+---
+id: acfad6b5-9a2c-4e51-9525-04b4c4112e69
+type: decision
+title: "Decision: fish config.fish exports SHELL=/bin/bash for tool compatibility"
+tags: [fish, bash, dotfiles, workstation, shell, config]
+importance: 0.6
+confidence: 0.8
+created: "2026-02-27T05:55:50.719305+00:00"
+updated: "2026-02-27T05:55:50.719305+00:00"
+---
+
+# Decision: fish config.fish exports SHELL=/bin/bash for tool compatibility
+
+## Decision
+`~/.config/fish/config.fish` has `set -x SHELL /bin/bash` on line 1.
+
+## Rationale
+Tools that spawn subshells based on `$SHELL` (tmux panes, editors like Neovim, some scripts) will use bash rather than fish. Fish is the interactive shell for Cal's terminal experience, but bash remains the scripting/subshell language. This avoids breakage in tools that assume POSIX-ish shell behaviour when they read `$SHELL`.
+
+## Scope
+- Fish is the **interactive** login shell (set via `chsh`)
+- Bash is the **subshell/scripting** shell (exported via `$SHELL`)
+- Claude Code is **unaffected** — it spawns its own internal bash regardless of the user's `$SHELL`
+
+## Do Not Change
+Do not update this line to `/usr/bin/fish`. If tooling issues arise with bash subshells, investigate the specific tool rather than removing this override.
+
+## File
+`/home/cal/.config/fish/config.fish`, line 1