diff --git a/aai_cli/agent/voices.py b/aai_cli/agent/voices.py
index 91aa1690..f53bb20d 100644
--- a/aai_cli/agent/voices.py
+++ b/aai_cli/agent/voices.py
@@ -2,6 +2,8 @@
 
 from dataclasses import dataclass
 
+from aai_cli.core import choices
+
 
 @dataclass(frozen=True)
 class Voice:
@@ -71,4 +73,4 @@ def format_voice_list() -> str:
 
 def complete_voice(incomplete: str) -> list[str]:
     """Shell-completion callback for ``--voice``: known voice ids matching the prefix."""
-    return [name for name in VOICE_NAMES if name.startswith(incomplete)]
+    return choices.complete_prefix(VOICE_NAMES, incomplete)
diff --git a/aai_cli/agent_framework/voices.py b/aai_cli/agent_framework/voices.py
index de55bb6f..57bdc006 100644
--- a/aai_cli/agent_framework/voices.py
+++ b/aai_cli/agent_framework/voices.py
@@ -9,6 +9,7 @@
 
 from __future__ import annotations
 
+from aai_cli.core import choices
 from aai_cli.tts import voices as tts_voices
 
 DEFAULT_VOICE = "jane"
@@ -29,7 +30,7 @@
 
 def complete_voice(incomplete: str) -> list[str]:
     """Shell-completion callback for ``--voice``: catalog ids matching the prefix."""
-    return [name for name in VOICE_NAMES if name.startswith(incomplete)]
+    return choices.complete_prefix(VOICE_NAMES, incomplete)
 
 
 def format_voice_list() -> str:
diff --git a/aai_cli/app/agent_shared.py b/aai_cli/app/agent_shared.py
new file mode 100644
index 00000000..27699dab
--- /dev/null
+++ b/aai_cli/app/agent_shared.py
@@ -0,0 +1,27 @@
+"""Run-logic shared by the two voice commands (`agent` and `agent-framework`).
+
+Both build a live terminal conversation and resolve the persona the same way, so
+the shared piece lives in the `app/` layer (the `doctor_checks`/`setup_exec`
+precedent) rather than being copied between the two command packages.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from aai_cli.core.errors import CLIError
+
+
+def resolve_system_prompt(system_prompt: str, system_prompt_file: Path | None) -> str:
+    """The persona text: a --system-prompt-file (if given) overrides --system-prompt."""
+    if system_prompt_file is None:
+        return system_prompt
+    try:
+        return system_prompt_file.read_text(encoding="utf-8")
+    except OSError as exc:
+        raise CLIError(
+            f"Could not read --system-prompt-file {system_prompt_file}: {exc}",
+            error_type="file_not_found",
+            exit_code=2,
+            suggestion="Check the path and that the file is readable.",
+        ) from exc
diff --git a/aai_cli/commands/agent/_exec.py b/aai_cli/commands/agent/_exec.py
index 00395438..60c16441 100644
--- a/aai_cli/commands/agent/_exec.py
+++ b/aai_cli/commands/agent/_exec.py
@@ -20,9 +20,10 @@
 from aai_cli.agent.render import AgentRenderer
 from aai_cli.agent.session import AgentRunConfig, run_session
 from aai_cli.agent.voices import VOICE_NAMES
+from aai_cli.app.agent_shared import resolve_system_prompt as _resolve_system_prompt
 from aai_cli.app.context import AppState
 from aai_cli.core import choices, client
-from aai_cli.core.errors import CLIError, UsageError
+from aai_cli.core.errors import UsageError
 from aai_cli.streaming.session import resolve_output_modes
 from aai_cli.streaming.sources import FileSource
 from aai_cli.ui import output
@@ -48,21 +49,6 @@ class AgentOptions:
     show_code: bool
 
 
-def _resolve_system_prompt(system_prompt: str, system_prompt_file: Path | None) -> str:
-    """The persona text: a --system-prompt-file (if given) overrides --system-prompt."""
-    if system_prompt_file is None:
-        return system_prompt
-    try:
-        return system_prompt_file.read_text(encoding="utf-8")
-    except OSError as exc:
-        raise CLIError(
-            f"Could not read --system-prompt-file {system_prompt_file}: {exc}",
-            error_type="file_not_found",
-            exit_code=2,
-            suggestion="Check the path and that the file is readable.",
-        ) from exc
-
-
 def _open_audio(
     renderer: AgentRenderer,
     *,
diff --git a/aai_cli/commands/agent_framework/_exec.py b/aai_cli/commands/agent_framework/_exec.py
index 71ee6d8d..5b7aefdc 100644
--- a/aai_cli/commands/agent_framework/_exec.py
+++ b/aai_cli/commands/agent_framework/_exec.py
@@ -18,9 +18,10 @@
 from aai_cli.agent.render import AgentRenderer
 from aai_cli.agent_framework import engine, voices
 from aai_cli.agent_framework.config import CascadeConfig
+from aai_cli.app.agent_shared import resolve_system_prompt as _resolve_system_prompt
 from aai_cli.app.context import AppState
 from aai_cli.core import choices, client
-from aai_cli.core.errors import CLIError, UsageError
+from aai_cli.core.errors import UsageError
 from aai_cli.streaming.session import resolve_output_modes
 from aai_cli.streaming.sources import FileSource
 from aai_cli.tts import session as tts_session
@@ -46,21 +47,6 @@ class AgentFrameworkOptions:
     output_field: choices.TextOrJson | None
 
 
-def _resolve_system_prompt(system_prompt: str, system_prompt_file: Path | None) -> str:
-    """The persona text: a --system-prompt-file (if given) overrides --system-prompt."""
-    if system_prompt_file is None:
-        return system_prompt
-    try:
-        return system_prompt_file.read_text(encoding="utf-8")
-    except OSError as exc:
-        raise CLIError(
-            f"Could not read --system-prompt-file {system_prompt_file}: {exc}",
-            error_type="file_not_found",
-            exit_code=2,
-            suggestion="Check the path and that the file is readable.",
-        ) from exc
-
-
 def _open_audio(
     renderer: AgentRenderer,
     *,
diff --git a/aai_cli/core/choices.py b/aai_cli/core/choices.py
index b54961c2..fe3d4da6 100644
--- a/aai_cli/core/choices.py
+++ b/aai_cli/core/choices.py
@@ -1,6 +1,13 @@
 from __future__ import annotations
 
 import enum
+from collections.abc import Iterable
+
+
+def complete_prefix(options: Iterable[str], incomplete: str) -> list[str]:
+    """Shell-completion callback body: the ``options`` that start with the typed prefix."""
+    return [option for option in options if option.startswith(incomplete)]
+
 
 # CLI-owned closed value sets for ``-o/--output``. ``StrEnum`` members *are* their
 # string values: Typer renders them as choices in ``--help`` (e.g.
diff --git a/aai_cli/core/llm.py b/aai_cli/core/llm.py
index 2f9fc740..c27e0aac 100644
--- a/aai_cli/core/llm.py
+++ b/aai_cli/core/llm.py
@@ -4,7 +4,7 @@
 from collections.abc import Sequence
 from typing import TYPE_CHECKING
 
-from aai_cli.core import environments
+from aai_cli.core import choices, environments
 from aai_cli.core.errors import APIError, UsageError, auth_failure
 
 if TYPE_CHECKING:
@@ -41,7 +41,7 @@ def complete_model(incomplete: str) -> list[str]:
     The gateway accepts more than this curated list, so completion only *suggests*
     these — it never restricts what you can type.
     """
-    return [m for m in KNOWN_MODELS if m.startswith(incomplete)]
+    return choices.complete_prefix(KNOWN_MODELS, incomplete)
 
 
 def parse_gateway_overrides(pairs: Sequence[str]) -> dict[str, object]:
diff --git a/tests/test_agent_framework_command.py b/tests/test_agent_framework_command.py
index cd4d4f52..2a9a5798 100644
--- a/tests/test_agent_framework_command.py
+++ b/tests/test_agent_framework_command.py
@@ -116,6 +116,8 @@ def test_resolve_system_prompt_unreadable_file_errors(tmp_path):
     with pytest.raises(CLIError, match="Could not read --system-prompt-file") as exc:
         _exec._resolve_system_prompt("x", missing)
     assert exc.value.exit_code == 2
+    assert exc.value.error_type == "file_not_found"
+    assert "readable" in (exc.value.suggestion or "")
 
 
 # --- _open_audio -------------------------------------------------------------
diff --git a/tests/test_completion.py b/tests/test_completion.py
index 24635e71..87802973 100644
--- a/tests/test_completion.py
+++ b/tests/test_completion.py
@@ -3,10 +3,17 @@
 import typer
 
 from aai_cli.agent.voices import VOICE_NAMES, complete_voice
+from aai_cli.core import choices
 from aai_cli.core.llm import KNOWN_MODELS, complete_model
 from aai_cli.main import app
 
 
+def test_complete_prefix_keeps_only_matching_options():
+    # The shared completion body that complete_voice/complete_model delegate to: it
+    # filters to the prefix (dropping "banana") rather than echoing every option back.
+    assert choices.complete_prefix(["apple", "apricot", "banana"], "ap") == ["apple", "apricot"]
+
+
 def test_shell_completion_is_enabled():
     # add_completion=True registers Typer's --install-completion on the root command.
     # Introspect the Click command rather than rendered --help text, which wraps at