fix(capy): label config-sourced agent_model, note the assumption, skip it inside eval runs (GST-982 review)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

bin/gstack-capy-install

@@ -724,9 +724,13 @@ fi
 [ "$RC" -eq 0 ] || { [ "$PROFILE" -eq 1 ] && rm -rf "${VERDICT%.json}.profile" 2>/dev/null; verdict_kept || rm -f "$LAUNCH_FILE" 2>/dev/null; LAUNCH_FILE=""; }
 record_verdict "$TRAILER" "$([ "$RC" -eq 0 ] && echo 1 || echo 0)"
 LOADOUT_LINES=""
-if [ "$RC" -eq 0 ] && [ -z "$MODEL" ] && [ -n "${GSTACK_PREFERENCES_FILE:-}" ] && [ "$PROFILE" -eq 0 ] && [ -n "$LAUNCH_FILE" ]; then
-  MODEL=$(cd "$ROOT" && bin/gstack-models resolve --role agent 2>/dev/null | sed -n '1s|^agent: [a-z0-9-]*/\([A-Za-z0-9._-]*\) .*|\1|p')
-  MODEL_SOURCE=preferences
+if [ "$RC" -eq 0 ] && [ -z "$MODEL" ] && [ -n "${GSTACK_PREFERENCES_FILE:-}" ] && [ -z "${GSTACK_EVAL_DIR:-}${EVALS_RUN_ID:-}" ] && [ "$PROFILE" -eq 0 ] && [ -n "$LAUNCH_FILE" ]; then
+  _ag_first=$(cd "$ROOT" && bin/gstack-models resolve --role agent 2>/dev/null | head -1)
+  case "$_ag_first" in
+    *", this machine") MODEL_SOURCE=config ;;
+    *", the preferences file") MODEL_SOURCE=preferences ;;
+  esac
+  [ "$MODEL_SOURCE" = GSTACK_MODEL ] || MODEL=$(printf '%s' "$_ag_first" | sed -n 's|^agent: [a-z0-9-]*/\([A-Za-z0-9._-]*\) .*|\1|p')
 fi
 if [ "$RC" -eq 0 ] && [ -n "$MODEL" ] && [ "$PROFILE" -eq 0 ] && [ -n "$LAUNCH_FILE" ]; then
   _lo_full=$(. "$SELF/bin/gstack-claude-root.sh" && dirname "$(gstack_canonical_claude_root)")
@@ -736,9 +740,11 @@ if [ "$RC" -eq 0 ] && [ -n "$MODEL" ] && [ "$PROFILE" -eq 0 ] && [ -n "$LAUNCH_F
     _lo_out=$(cd "$ROOT" && bin/gstack-modules install --model "$MODEL" --full-root "$_lo_full" 2>&1)
   fi
   _lo_line=$(printf '%s\n' "$_lo_out" | grep -m1 '^LOADOUT: ')
-  [ "$MODEL_SOURCE" = preferences ] && _lo_line=$(printf '%s' "$_lo_line" | sed 's/ source=model-flag/ source=preferences/')
+  case "$MODEL_SOURCE" in preferences|config) _lo_line=$(printf '%s' "$_lo_line" | sed "s/ source=model-flag/ source=$MODEL_SOURCE/") ;; esac
   _lo_root=$(printf '%s\n' "$_lo_out" | sed -n 's/^SKILL_ROOT: //p' | head -1)
   _lo_notes=$(printf '%s\n' "$_lo_out" | grep -E '^(LOADOUT_INVALID_MODEL|LOADOUT_FALLBACK): ')
+  case "$MODEL_SOURCE" in preferences|config) _lo_notes="${_lo_notes:+$_lo_notes
+}LOADOUT_ASSUMED: model=$MODEL is the owner's agent_model ($MODEL_SOURCE), not read from the session; a session on another model sets GSTACK_MODEL=<its id>" ;; esac
   _lo_name=$(printf '%s' "$_lo_line" | sed -n 's/^LOADOUT: \([a-z0-9-]*\) .*/\1/p')
   _lo_digest=$(printf '%s' "$_lo_line" | sed -n 's/.* digest=\([0-9a-f]\{12\}\) .*/\1/p')
   if [ -n "$_lo_name" ] && [ "$_lo_name" != full ]; then

changelog.d/gsta161-gst-982-capy-model.md

@@ -1,7 +1,7 @@
 **Capy sessions get their model's loadout again without a sentence in the skill (GST-982).** The browse wave (#3858) removed the Capy skill's instruction to run the installer with `GSTACK_MODEL`, to keep `capy/skill/gstack/SKILL.md` under its context budget. After that, every Capy session installed the full skills, including Opus 5.5 sessions that should get `lite`. Now the installer finds the model by itself.
 
 ### Fixed
-- **`gstack-capy-install` reads the owner's model preference.** When it gets no `--model` and no `GSTACK_MODEL`, it uses the `agent_model` in the session's `GSTACK_PREFERENCES_FILE` (the Drive skill's `preferences.yaml`, which `gstack-capy-session` already exports), resolved by `gstack-models resolve --role agent`. So `opus` means `claude-opus-5-5` today. The line reads `LOADOUT: … source=preferences`. `GSTACK_MODEL` and `--model` still win, and a `host` preference or no file still serves full. The frozen bootstrapper `capy/skill/gstack/scripts/install.sh` and the skill text are unchanged.
+- **`gstack-capy-install` reads the owner's model preference.** When it gets no `--model` and no `GSTACK_MODEL`, it uses the `agent_model` in the session's `GSTACK_PREFERENCES_FILE` (the Drive skill's `preferences.yaml`, which `gstack-capy-session` already exports), resolved by `gstack-models resolve --role agent`. So `opus` means `claude-opus-5-5` today. The line reads `LOADOUT: … source=preferences` (`source=config` when this machine's `config.yaml` sets it), followed by a `LOADOUT_ASSUMED:` note that the model came from the preference and not the session. Eval runs (`GSTACK_EVAL_DIR` or `EVALS_RUN_ID` set) skip the preference. `GSTACK_MODEL` and `--model` still win, and a `host` preference or no file still serves full. The frozen bootstrapper `capy/skill/gstack/scripts/install.sh` and the skill text are unchanged.
 
 ### Tests
-- `test/gstack-capy-install.test.ts`: an `opus` preference picks lite with `source=preferences` and its own launch file, `GSTACK_MODEL` overrides the preference, a `host` preference prints no loadout lines, and the real `gstack-models resolve --role agent` keeps the `agent: <provider>/<model>` first line the installer reads.
+- `test/gstack-capy-install.test.ts`: an `opus` preference picks lite with `source=preferences` and its own launch file, `GSTACK_MODEL` overrides the preference, a `config.yaml` preference reads `source=config`, eval runs skip the preference, a `host` preference prints no loadout lines, and the real `gstack-models resolve --role agent` keeps the `agent: <provider>/<model>` first line the installer reads.

docs/capy-install.md

@@ -473,7 +473,8 @@ make <dir> writable, or set GSTACK_STATE_ROOT to a writable directory
 and removes the file an earlier passing run left beside the verdict it rewrites
 (a profile check that keeps a fuller ok verdict leaves that verdict's file).
 With `--model <id>`, `GSTACK_MODEL=<id>` in its environment, or else an
-`agent_model` in the session's `GSTACK_PREFERENCES_FILE` (GST-982), an ok run other than `--for review-voice` also prints `LOADOUT: …`
+`agent_model` in the session's `GSTACK_PREFERENCES_FILE` outside an eval run (GST-982, with a
+`LOADOUT_ASSUMED:` note), an ok run other than `--for review-voice` also prints `LOADOUT: …`
 and `SKILL_ROOT: <dir>` just before `GSTACK_LAUNCH`. For a loadout other than
 `full`, `GSTACK_LAUNCH_FILE` then names `<verdict file without .json>.loadout-<name>-<digest>.env`,
 a copy of the verdict's launch file that adds `GSTACK_LOADOUT_SKILL_ROOT`; the

docs/loadouts.md

@@ -55,7 +55,7 @@ A model id is lowercased, its `provider/` prefix and a trailing `[…]` are drop
 
 ### Capy
 
-A plain `bash scripts/install.sh --check --for <skill>` picks the loadout from the owner's `agent_model` preference, so the skill needs no model sentence (`source=preferences` on the line below). A session can still name its own model with `GSTACK_MODEL=<id>`, which wins over the preference and, unlike `--model`, is safe on a checkout whose installer predates loadouts: that installer ignores it instead of refusing an unknown argument. The installer prints two lines before the launch lines:
+A plain `bash scripts/install.sh --check --for <skill>` picks the loadout from the owner's `agent_model` preference, so the skill needs no model sentence (`source=preferences` on the line below, or `source=config` when this machine's `config.yaml` sets `agent_model`). The preference names the model Garry starts sessions on, not the model reading the skill, so the installer says so in a `LOADOUT_ASSUMED:` line, and it skips the preference inside an eval run (`GSTACK_EVAL_DIR` or `EVALS_RUN_ID` set), where the model under test may differ. A session on another model names its own with `GSTACK_MODEL=<id>`, which wins over the preference and, unlike `--model`, is safe on a checkout whose installer predates loadouts: that installer ignores it instead of refusing an unknown argument. The installer prints two lines before the launch lines:
 
 ```
 LOADOUT: lite model=claude-opus-5-5 source=GSTACK_MODEL digest=3f2a9c01d4e7 reused=yes

test/gstack-capy-install.test.ts

@@ -605,6 +605,7 @@ describe('gstack-capy-install: launch PATH, Bun reuse, CI pins, setup skip, verd
     ]);
     script(path.join(f.root, 'bin/gstack-models'), [
       'echo "models $* prefs=${GSTACK_PREFERENCES_FILE:-}" >> "$CAPY_LOG"',
+      '[ -z "${FAKE_CONFIG_MODEL:-}" ] || { echo "agent: anthropic/$FAKE_CONFIG_MODEL (opus) - from agent_model in $HOME/.gstack/config.yaml, this machine"; exit 0; }',
       'case "$(sed -n "s/^agent_model: *//p" "${GSTACK_PREFERENCES_FILE:-/dev/null}" 2>/dev/null)" in',
       '  opus) echo "agent: anthropic/claude-opus-5-5 (opus) - from agent_model in $GSTACK_PREFERENCES_FILE, the preferences file" ;;',
       '  *) echo "agent: host - keep the running agent\'s own model and omit the model field (no preference set)" ;;',
@@ -618,6 +619,20 @@ describe('gstack-capy-install: launch PATH, Bun reuse, CI pins, setup skip, verd
     expect(f.calls().filter(l => l.startsWith('modules '))).toEqual([`modules install --model claude-opus-5-5 --full-root ${f.home}/.claude/skills`]);
     expect(opus.stdout).toContain(`LOADOUT: lite model=claude-opus-5-5 source=preferences digest=0123456789ab reused=no\nSKILL_ROOT: ${f.home}/lite-0123456789ab\n`);
     expect(launchOf(opus.stdout)).toBe(verdicts(f)[0].replace(/\.json$/, '.loadout-lite-0123456789ab.env'));
+    expect(opus.stdout).toContain("LOADOUT_ASSUMED: model=claude-opus-5-5 is the owner's agent_model (preferences), not read from the session; a session on another model sets GSTACK_MODEL=<its id>\n");
+
+    const config = run(f, ['--for', 'ship'], { GSTACK_PREFERENCES_FILE: prefs, FAKE_CONFIG_MODEL: 'claude-opus-5-5' });
+    expect(config.status, config.stdout + config.stderr).toBe(0);
+    expect(config.stdout).toContain('LOADOUT: lite model=claude-opus-5-5 source=config digest=0123456789ab');
+    expect(config.stdout).toContain("is the owner's agent_model (config)");
+
+    const modulesBefore = f.calls().filter(l => l.startsWith('modules ')).length;
+    for (const evalEnv of [{ GSTACK_EVAL_DIR: path.join(f.home, 'evals') }, { EVALS_RUN_ID: 'r1' }]) {
+      const ev = run(f, ['--for', 'ship'], { GSTACK_PREFERENCES_FILE: prefs, ...evalEnv });
+      expect(ev.status, ev.stdout + ev.stderr).toBe(0);
+      expect(ev.stdout).not.toMatch(/^(LOADOUT|LOADOUT_ASSUMED|SKILL_ROOT):/m);
+    }
+    expect(f.calls().filter(l => l.startsWith('modules ')).length).toBe(modulesBefore);
 
     const env = run(f, ['--for', 'ship'], { GSTACK_PREFERENCES_FILE: prefs, GSTACK_MODEL: 'claude-sonnet-5-5' });
     expect(env.status, env.stdout + env.stderr).toBe(0);