fix(terminal): keep legacy bash prompt dispatch out of OSC 133 command start after a DEBUG trap change (#29165)

On bash <= 5.0 the PROMPT_COMMAND is a single scalar string. After the
user changed the DEBUG trap at the prompt (`trap - DEBUG`, `trap ':' DEBUG`),
Orca's preexec never saw the status-capture command, so the legacy wrapper
flag stayed unset and the dispatch tail emitted OSC 133;C before the next
prompt was drawn.

Set __orca_in_legacy_prompt_wrapper directly in the PROMPT_COMMAND string,
and re-arm the Orca DEBUG trap at the top level of that string: bash <= 4.3
(including macOS /bin/bash 3.2) restores the caller's DEBUG trap when a
function returns, so the re-arm inside __orca_finish_legacy_prompt_dispatch
was undone. Tests force the legacy dispatch on any bash and also run with
/bin/bash on macOS.

Fixes #29164

Co-authored-by: Neil <neil@stably.ai>

src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt

@@ -372,8 +372,6 @@ __orca_finish_legacy_prompt_dispatch() {
       eval "$__orca_suffix_part"
     done
   fi
-  trap '__orca_osc133_preexec' DEBUG
-  unset __orca_in_legacy_prompt_wrapper
 }
 __orca_normalize_prompt_command() {
   [[ -z "${__orca_prompt_command_normalized:-}" ]] || return 0
@@ -395,7 +393,8 @@ __orca_normalize_prompt_command() {
     __orca_prompt_status_variable="__orca_prompt_status_$$"
     __orca_prompt_status_capture_command="$__orca_prompt_status_variable=\$?"
     __orca_prompt_status_value="\${$__orca_prompt_status_variable}"
-    PROMPT_COMMAND="$__orca_prompt_status_capture_command; __orca_prompt_status=$__orca_prompt_status_value"'; __orca_prompt_had_functrace=""; if [[ -o functrace ]]; then __orca_prompt_had_functrace=1; set +T; fi; __orca_outer_debug_trap_spec="$(trap -p DEBUG)"; [[ -z "$__orca_prompt_had_functrace" ]] || set -T; unset __orca_prompt_had_functrace; __orca_run_prompt_command_array; __orca_finish_legacy_prompt_dispatch'
+    # Why: a changed DEBUG trap misses the capture command, and bash <= 4.3 reverts traps set in functions.
+    PROMPT_COMMAND="$__orca_prompt_status_capture_command; __orca_in_legacy_prompt_wrapper=1; __orca_prompt_status=$__orca_prompt_status_value"'; __orca_prompt_had_functrace=""; if [[ -o functrace ]]; then __orca_prompt_had_functrace=1; set +T; fi; __orca_outer_debug_trap_spec="$(trap -p DEBUG)"; [[ -z "$__orca_prompt_had_functrace" ]] || set -T; unset __orca_prompt_had_functrace; __orca_run_prompt_command_array; __orca_finish_legacy_prompt_dispatch; trap __orca_osc133_preexec DEBUG; unset __orca_in_legacy_prompt_wrapper'
   fi
 }
 __orca_prepend_prompt_command() {

src/main/__fixtures__/shell-wrapper-snapshots/local-bash-rcfile.txt

@@ -365,8 +365,6 @@ __orca_finish_legacy_prompt_dispatch() {
       eval "$__orca_suffix_part"
     done
   fi
-  trap '__orca_osc133_preexec' DEBUG
-  unset __orca_in_legacy_prompt_wrapper
 }
 __orca_normalize_prompt_command() {
   [[ -z "${__orca_prompt_command_normalized:-}" ]] || return 0
@@ -388,7 +386,8 @@ __orca_normalize_prompt_command() {
     __orca_prompt_status_variable="__orca_prompt_status_$$"
     __orca_prompt_status_capture_command="$__orca_prompt_status_variable=\$?"
     __orca_prompt_status_value="\${$__orca_prompt_status_variable}"
-    PROMPT_COMMAND="$__orca_prompt_status_capture_command; __orca_prompt_status=$__orca_prompt_status_value"'; __orca_prompt_had_functrace=""; if [[ -o functrace ]]; then __orca_prompt_had_functrace=1; set +T; fi; __orca_outer_debug_trap_spec="$(trap -p DEBUG)"; [[ -z "$__orca_prompt_had_functrace" ]] || set -T; unset __orca_prompt_had_functrace; __orca_run_prompt_command_array; __orca_finish_legacy_prompt_dispatch'
+    # Why: a changed DEBUG trap misses the capture command, and bash <= 4.3 reverts traps set in functions.
+    PROMPT_COMMAND="$__orca_prompt_status_capture_command; __orca_in_legacy_prompt_wrapper=1; __orca_prompt_status=$__orca_prompt_status_value"'; __orca_prompt_had_functrace=""; if [[ -o functrace ]]; then __orca_prompt_had_functrace=1; set +T; fi; __orca_outer_debug_trap_spec="$(trap -p DEBUG)"; [[ -z "$__orca_prompt_had_functrace" ]] || set -T; unset __orca_prompt_had_functrace; __orca_run_prompt_command_array; __orca_finish_legacy_prompt_dispatch; trap __orca_osc133_preexec DEBUG; unset __orca_in_legacy_prompt_wrapper'
   fi
 }
 __orca_prepend_prompt_command() {

src/main/bash-prompt-command-composition.ts

@@ -133,8 +133,6 @@ __orca_finish_legacy_prompt_dispatch() {
       eval "$__orca_suffix_part"
     done
   fi
-  trap '__orca_osc133_preexec' DEBUG
-  unset __orca_in_legacy_prompt_wrapper
 }
 __orca_normalize_prompt_command() {
   [[ -z "\${__orca_prompt_command_normalized:-}" ]] || return 0
@@ -156,7 +154,8 @@ __orca_normalize_prompt_command() {
     __orca_prompt_status_variable="__orca_prompt_status_$$"
     __orca_prompt_status_capture_command="$__orca_prompt_status_variable=\\$?"
     __orca_prompt_status_value="\\\${$__orca_prompt_status_variable}"
-    PROMPT_COMMAND="$__orca_prompt_status_capture_command; __orca_prompt_status=$__orca_prompt_status_value"'; __orca_prompt_had_functrace=""; if [[ -o functrace ]]; then __orca_prompt_had_functrace=1; set +T; fi; __orca_outer_debug_trap_spec="$(trap -p DEBUG)"; [[ -z "$__orca_prompt_had_functrace" ]] || set -T; unset __orca_prompt_had_functrace; __orca_run_prompt_command_array; __orca_finish_legacy_prompt_dispatch'
+    # Why: a changed DEBUG trap misses the capture command, and bash <= 4.3 reverts traps set in functions.
+    PROMPT_COMMAND="$__orca_prompt_status_capture_command; __orca_in_legacy_prompt_wrapper=1; __orca_prompt_status=$__orca_prompt_status_value"'; __orca_prompt_had_functrace=""; if [[ -o functrace ]]; then __orca_prompt_had_functrace=1; set +T; fi; __orca_outer_debug_trap_spec="$(trap -p DEBUG)"; [[ -z "$__orca_prompt_had_functrace" ]] || set -T; unset __orca_prompt_had_functrace; __orca_run_prompt_command_array; __orca_finish_legacy_prompt_dispatch; trap __orca_osc133_preexec DEBUG; unset __orca_in_legacy_prompt_wrapper'
   fi
 }
 __orca_prepend_prompt_command() {

src/main/daemon/bash-prompt-command-composition.test.ts

@@ -13,18 +13,21 @@ const bashMajor = hasBash
 const bashMinor = hasBash
   ? Number(spawnSync('bash', ['-lc', 'printf %s "${BASH_VERSINFO[1]}"']).stdout)
   : 0
+const LEGACY_GATE = 'BASH_VERSINFO[0] > 5 || (BASH_VERSINFO[0] == 5 && BASH_VERSINFO[1] >= 1)'
 const bashPreservesOddTerminalBackslash = bashMajor > 4 || (bashMajor === 4 && bashMinor >= 4)
 
 function runInteractiveBash(
   profile: string,
   tempHome: string,
-  input = 'true\nfalse\nexit 0\n'
+  input = 'true\nfalse\nexit 0\n',
+  rcfileContent = getDaemonBashShellReadyRcfileContent(),
+  bash = 'bash'
 ): string {
   const rcfile = join(tempHome, 'rcfile')
   writeFileSync(join(tempHome, '.bash_profile'), profile)
-  writeFileSync(rcfile, getDaemonBashShellReadyRcfileContent())
+  writeFileSync(rcfile, rcfileContent)
   const result = spawnSync(
-    'bash',
+    bash,
     ['-lc', '"$BASH" --noprofile --rcfile "$1" -i 2>&1', 'bash', rcfile],
     {
       input,
@@ -396,6 +399,37 @@ PROMPT_COMMAND='printf "PROMPT_REMATCH:<%s>\\n" "\${BASH_REMATCH[1]-unset}"'
     expectLifecycle(output)
   })
 
+  // Why: macOS /bin/bash 3.2 also reverts DEBUG traps set inside functions.
+  const legacyBashes = process.platform === 'darwin' ? ['bash', '/bin/bash'] : ['bash']
+  itWithBash.each(
+    legacyBashes.flatMap((bash) => [
+      ['trap - DEBUG', bash],
+      ["trap ':' DEBUG", bash]
+    ])
+  )(
+    'starts the next command after its prompt when `%s` runs at a legacy prompt (%s)',
+    (trapChange, bash) => {
+      // Why: force the bash <= 5.0 scalar PROMPT_COMMAND dispatch on any bash.
+      const rcfile = getDaemonBashShellReadyRcfileContent()
+      expect(rcfile).toContain(LEGACY_GATE)
+      const legacyRcfile = rcfile.replaceAll(LEGACY_GATE, '0')
+      const output = runInteractiveBash(
+        "PS1='ORCA_PS1> '",
+        tempHome,
+        `${trapChange}\ntrue\nexit 0\n`,
+        legacyRcfile,
+        bash
+      )
+      const startBeforePrompt = new RegExp(
+        `${String.fromCharCode(27)}]133;A${String.fromCharCode(7)}(?:(?!ORCA_PS1> )[\\s\\S])*${String.fromCharCode(27)}]133;C`
+      )
+
+      expect(output).toContain('ORCA_PS1> ')
+      expect(output).not.toMatch(startBeforePrompt)
+      expectLifecycle(output, 0)
+    }
+  )
+
   itWithBash('does not treat user command text as a bash-preexec helper', () => {
     const output = runInteractiveBash('', tempHome, 'echo a:__bp_x\nfalse\nexit 0\n')
 

src/main/providers/local-pty-shell-ready-wrapper-generation.test.ts

@@ -398,6 +398,27 @@ describePosix('local PTY shell-ready launch config', () => {
     expectBashOsc133Lifecycle(output)
   })
 
+  itWithBash(
+    'starts the next command after its prompt when the DEBUG trap is removed at a legacy prompt',
+    () => {
+      // Why: force the bash <= 5.0 scalar PROMPT_COMMAND dispatch on any bash.
+      const gate = 'BASH_VERSINFO[0] > 5 || (BASH_VERSINFO[0] == 5 && BASH_VERSINFO[1] >= 1)'
+      const rcfile = getBashShellReadyRcfileContent()
+      expect(rcfile).toContain(gate)
+      const legacyRcfile = rcfile.replaceAll(gate, '0')
+      writeFileSync(join(userDataPath, '.bash_profile'), "PS1='ORCA_PS1> '\n")
+      const input = 'trap - DEBUG\nfalse\nexit 0\n'
+      const output = runInteractiveBashRcfile(legacyRcfile, userDataPath, input)
+      const startBeforePrompt = new RegExp(
+        `${String.fromCharCode(27)}]133;A${String.fromCharCode(7)}(?:(?!ORCA_PS1> )[\\s\\S])*${String.fromCharCode(27)}]133;C`
+      )
+
+      expect(output).toContain('ORCA_PS1> ')
+      expect(output).not.toMatch(startBeforePrompt)
+      expectBashOsc133Lifecycle(output)
+    }
+  )
+
   itWithBash('composes an inherited PROMPT_COMMAND ending in separators', () => {
     writeFileSync(
       join(userDataPath, '.bash_profile'),