ai: apply changes for #862 (1 review thread)

Addresses:
  - #3598984213 at .github/workflows/engineer-bot.yml:145

Author: peco-engineer-bot[bot]

.github/workflows/engineer-bot.yml

@@ -2,11 +2,12 @@
 #
 # A maintainer labels an ISSUE with `engineer-bot`; the bot addresses it and opens
 # a PR. The author FLOW is chosen from the issue's TYPE (a GitHub org-level Issue
-# Type): `Bug` ⇒ bug-fix (reproduce with a failing test, then fix); `Task`/`Feature`
-# ⇒ task (smallest correct change); any other type / none ⇒ the repo's
-# .bot/config.yaml `flow:` default. Set the Type BEFORE `engineer-bot` — it's read
-# live when the run starts. Driven by the selected flow + this repo's .bot/
-# (config + prompts).
+# Type): `Bug` ⇒ bug-fix (reproduce with a failing test, then fix); any other type
+# / none ⇒ the repo's .bot/config.yaml `flow:` default (also bug-fix). Only bug-fix
+# is selectable because this repo's .bot/prompts/engineer/ prompts are written
+# exclusively for it; a task-flavored flow would need matching prompts first. Set
+# the Type BEFORE `engineer-bot` — it's read live when the run starts. Driven by
+# the selected flow + this repo's .bot/ (config + prompts).
 #
 # The engineer builds and runs THIS repo's tests, so it needs the connector's
 # deps installed (via setup-poetry) in addition to the engine. Shared setup
@@ -135,14 +136,17 @@ jobs:
           # The type→flow MAPPING is pinned (not "use the type name as the flow")
           # so an arbitrary custom org type can never select an engine flow:
           #   Bug ⇒ bug-fix (red→green TDD)
-          #   Task/Feature ⇒ task (single-pass, smallest correct change; the engine
-          #     has no separate `enhancement` flow — it was renamed to `task`)
+          # Only `bug-fix` is mapped: this repo's .bot/prompts/engineer/{system,user}.md
+          # are written EXCLUSIVELY for the bug-fix flow ("reproduce the bug with a
+          # failing test, then fix"). Mapping Task/Feature ⇒ task would run the
+          # engine's single-pass `task` flow under a prompt that mandates red→green
+          # bug reproduction — a flow/prompt contradiction. Until flow-aware prompts
+          # exist, every run uses bug-fix.
           # Any other type or no type ⇒ emit nothing ⇒ the author step omits
-          # --flow ⇒ the engine uses .bot/config.yaml `flow:`.
+          # --flow ⇒ the engine uses .bot/config.yaml `flow:` default (bug-fix).
           TYPE="$(jq -r '.type.name // ""' "$RUNNER_TEMP/issue.json")"
           case "$TYPE" in
-            Bug)          echo "flow=bug-fix" >> "$GITHUB_OUTPUT" ;;
-            Task|Feature) echo "flow=task"    >> "$GITHUB_OUTPUT" ;;
+            Bug) echo "flow=bug-fix" >> "$GITHUB_OUTPUT" ;;
           esac
           DELIM="GHEOF_$(date +%s%N)${RANDOM}"
           if printf '%s' "$TITLE" | grep -qF "$DELIM"; then
@@ -160,8 +164,8 @@ jobs:
         # $GITHUB_ENV (the bot config's author.env_tokens).
         #
         # The author FLOW is chosen from the issue TYPE by the ctx step above
-        # (Bug ⇒ bug-fix, Task/Feature ⇒ task). We pass --flow ONLY when that
-        # step derived one: an empty --flow would be rejected by the CLI's
+        # (Bug ⇒ bug-fix; any other/none ⇒ config default). We pass --flow ONLY
+        # when that step derived one: an empty --flow would be rejected by the CLI's
         # `choices`, and omitting it lets the engine fall back to the
         # .bot/config.yaml `flow:` default (no/other type, or type-set-late case).
         working-directory: ${{ runner.temp }}