fix: keep narrated progress notes apart and name a delegated conductor

[cgaravitoq]

Row A3 of wave bloop-delegation-2, one logical step per commit.

E10 - two notes, one reply. Two progress milestones posted close together are dispatched into the same conversation Durable Object; Flue joins the second dispatch into the live response at a turn boundary and drives a continuation turn, so both narrations stream into one Slack delivery record and stream with nothing between the deltas ("...feedback.Carlos sigue..."). One reply per milestone is not reachable: the runtime has no opt-out from a join, and the only seam the app owns in that path is packages/core/src/delivery.ts. So the result is one reply whose notes are separated by a blank line: a delivery that joins a destination the record already answers, while that record carries reply text, prepends "\n\n" to the joined turn's first text delta. At the first text and not at the join, because a joining turn that answers with a tool call and no note would otherwise leave a stray separator, and a record resumed after a restart would keep a trailing one.

Q2 - a delegated milestone names its conductor. A milestone posted under a task token is the conductor's work, so its narration body now carries Delegation: the conductor <runner> is doing this task on the owner's behalf; name the conductor, never the owner, as the one working. between Task: and Status:. A milestone without a token (the progress bearer, even for task: "delegation:<id>") keeps the body it had, byte for byte. The name is the registered runner name from the token's task; the public repo says runner, conductor and task, never a machine or a vendor.

Receipts are untouched: one receipt per milestone, posted/narrated as before, and both milestones of a joined turn still answer 200 {"ok": true, "narrated": true}.

Verify

• Two milestones narrated in one turn yield text where the notes are separated - apps/slack-agent/test/delivery.test.ts "keeps a blank line between the notes a joined response carries". Red on base 0d453e1^: expect(slack.markdown()).toBe("Reviewed the feedback.\n\nNow on the fix.") received "Reviewed the feedback.Now on the fix.", the E10 glue with the space missing. Green at c40a74a, and the whole delivery.test.ts (106 tests) unchanged otherwise.
• A delegated milestone's narration body carries the conductor line - apps/slack-agent/test/delegation.test.ts "narrates a delegated milestone as the conductor's work, not the owner's". Red on base: the narrated body had no Delegation: paragraph; green at 24c076c with the paragraph asserted verbatim.
• A non-delegated one does not - the same test posts the same milestone under the progress bearer and expects no the conductor; progress.test.ts "narrates a milestone as one turn in its thread and posts no reply itself" still pins the exact body array for a non-delegated milestone, so the line cannot leak into it.
• bun run verify passes and CI verify is green - bun run verify green locally on 24c076c (format:check, lint, typecheck, 363 tests, knip, deploy:dry, bun audit clean). CI verify green on this PR: run 37675505815, 49s, pass.

Commits, in dependency order

1. 0d453e1 test: pin the glued notes a joined narration response carries (red on its own)
2. c40a74a fix: keep a blank line between the notes a joined reply carries
3. 24c076c feat: make a delegated milestone's narration name its conductor

Not covered

• The live re-run in staging (the conductor runs it after the pin), so E10's fix is proven by the delivery-level witness, not by a real Slack message from the joined turn.
• Wording in right-hand's narration config that still names the owner as the actor. The core now tells the model who works on a delegated task, but a config voice that says "Carlos" or "you, the owner" can still override it; the pin row can adjust that wording.