feat(sendblue): expose tapback action to the agent via send_message

The adapter's outbound send_reaction() (patch NousResearch#3) was reachable from
gateway code but invisible to the agent — no tool surface, and the
inbound message_handle (already on MessageEvent / SessionSource) was
never injected into the model-visible session-context block.

- gateway/session.py: Platform.SENDBLUE branch with iMessage notes plus
  a triggering-message-handle IDs block (current turn only).
- tools/send_message_tool.py: send_message gains action='react' with
  message_handle / reaction params, _handle_react validation arms, and
  a _react_sendblue dispatcher that mirrors _send_sendblue's throwaway-
  adapter pattern. _REACTION_PLATFORMS gates platform support.
- agent/prompt_builder.py: sharpen the sendblue blurb to point at the
  now-real send_message(action='react', ...) mechanism and the handle
  source (the original tapback line from patch NousResearch#4 was aspirational).
- tests/tools/test_sendblue_reaction.py: 15 tests covering dispatch,
  validation arms, schema, and reaction normalization.
- LOCAL_PATCHES.md: new patch NousResearch#11 entry + file-index updates.

Author: flux627

LOCAL_PATCHES.md

@@ -10,6 +10,8 @@ Last updated: 2026-05-02
 Pinned upstream base: `73bf3ab1b22314ed9dfecbb59242c03742fe72af`
 (release v0.12.0, 2026-04-30).
 
+Patches: #1–#11 (see numbered sections below).
+
 ---
 
 ## 1. Cron waker hook for external supervisors
@@ -316,6 +318,63 @@ and PDF — attachments land inline on iMessage.
 
 ---
 
+## 11. Sendblue tapback action exposed to the agent
+
+**Problem:** Patch #3's adapter ships with an outbound `send_reaction()`
+method (the only adapter on the fork that has one), but nothing in the
+agent-facing surface lets the model actually call it. The inbound
+`message_handle` was already plumbed through to
+`MessageEvent.message_id` and `SessionSource.message_id` (the
+`SessionSource` field even carries the comment "for pin/reply/react"),
+but it was never injected into the model-visible session-context block,
+so the model had no handle to react to. As a result the SendBlue
+tapback API was reachable from gateway code but invisible to the agent.
+
+**Solution:** Two small additions, no new files, no base-class changes.
+- `gateway/session.py` gains a `Platform.SENDBLUE` branch (mirrors the
+  BLUEBUBBLES iMessage notes verbatim) that, when the current turn has a
+  `message_id`, appends a `**iMessage IDs (for the `react` action of
+  `send_message`):**` block surfacing the triggering-message handle plus
+  a one-line invocation example. Only the current turn's handle is
+  exposed — historical handles are deliberately not embedded in the
+  transcript (would require cross-cutting prompt changes for marginal
+  agent benefit).
+- `tools/send_message_tool.py` grows an `action="react"` arm of the
+  existing `send_message` tool (rather than a new tool) so target
+  resolution and platform gating reuse the existing surface. New
+  `message_handle` and `reaction` schema params (with the closed
+  Sendblue reaction enum). New `_handle_react()` validator dispatches
+  to `_react_sendblue()`, which mirrors `_send_sendblue`'s throwaway-
+  adapter pattern and calls `adapter.send_reaction()`. A
+  `_REACTION_PLATFORMS = frozenset({"sendblue"})` gate makes the
+  one-platform restriction explicit and easy to grow.
+
+**Commits:**
+- _(pending — to be filled in on next snapshot build)_
+
+**Files modified:**
+- `gateway/session.py` — Platform.SENDBLUE branch + iMessage IDs block
+- `tools/send_message_tool.py` — schema, dispatcher arm, `_handle_react`,
+  `_react_sendblue`
+- `agent/prompt_builder.py` — sharpen the sendblue platform blurb to
+  reference the now-real `send_message(action='react', ...)` mechanism
+  and the session-context handle source (the original aspirational
+  tapback line from patch #4 was vague — the agent had no way to act on
+  it).
+
+**Files added:**
+- `tests/tools/test_sendblue_reaction.py` — 15 tests covering
+  `_react_sendblue` adapter dispatch, `_handle_react` validation arms
+  (missing target/handle/reaction, unsupported platform, missing chat_id,
+  unconfigured platform), reaction-name lower-casing, the `send_message`
+  dispatcher routing for `action='react'`, and schema advertisement of
+  the new action/params. Placed in upstream-owned `tests/tools/` per the
+  same new-file-OK exception documented in patch #5.
+
+**Drop when:** Same as #3.
+
+---
+
 ## File Index
 
 All files touched by local patches, grouped by area:
@@ -328,6 +387,7 @@ All files touched by local patches, grouped by area:
 - `gateway/config.py` — #4
 - `gateway/platforms/bluebubbles.py` — #2 (webhook env guard)
 - `gateway/platforms/sendblue.py` — #3 (adapter), #7 (auth probe)
+- `gateway/session.py` — #11 (sendblue tapback IDs block)
 
 ### CLI
 - `hermes_cli/platforms.py` — #4
@@ -339,13 +399,14 @@ All files touched by local patches, grouped by area:
 - `cron/waker_hook.py` — #1 (added), #4 (modified)
 
 ### Tools / agent prompts
-- `agent/prompt_builder.py` — #4
-- `tools/send_message_tool.py` — #4, #10
+- `agent/prompt_builder.py` — #4, #11
+- `tools/send_message_tool.py` — #4, #10, #11
 - `toolsets.py` — #4
 
 ### Tests
 - `tests/gateway/test_sendblue.py` — #5 (added; new file in upstream dir)
 - `tests/tools/test_sendblue_media.py` — #10 (added; new file in upstream dir)
+- `tests/tools/test_sendblue_reaction.py` — #11 (added; new file in upstream dir)
 - `tests/local_patches/__init__.py` — #8 (added)
 - `tests/local_patches/test_thinking_reasoning_pad.py` — #8 (added)
 

agent/prompt_builder.py

@@ -386,9 +386,13 @@ def _strip_yaml_frontmatter(content: str) -> str:
         "appear as text messages. You can send media files natively: include "
         "MEDIA:/absolute/path/to/file in your response. Images (.jpg, .png, "
         ".heic) appear as photos and other files arrive as attachments. You "
-        "can also send tapback reactions (love, like, dislike, laugh, "
-        "emphasize, question) when reacting to a recent message is more "
-        "appropriate than sending a reply."
+        "can also send a tapback reaction to the user's current message — "
+        "call send_message(action='react', target='sendblue:<chat_id>', "
+        "message_handle=<handle>, reaction=<love|like|dislike|laugh|emphasize|question>). "
+        "The message_handle is surfaced in the session-context block as "
+        "'Triggering message handle' and only refers to the message you are "
+        "currently answering; you cannot react to earlier messages. Prefer a "
+        "tapback over a one-word text reply when a quick acknowledgement fits."
     ),
     "mattermost": (
         "You are in a Mattermost workspace communicating with your user. "

gateway/session.py

@@ -365,6 +365,31 @@ def build_session_context_prompt(
             "If the user needs a detailed answer, give the short version first "
             "and offer to elaborate."
         )
+    elif context.source.platform == Platform.SENDBLUE:
+        lines.append("")
+        lines.append(
+            "**Platform notes:** You are responding via iMessage (Sendblue). "
+            "Keep responses short and conversational — think texts, not essays. "
+            "Structure longer replies as separate short thoughts, each separated "
+            "by a blank line (double newline). Each block between blank lines "
+            "will be delivered as its own iMessage bubble, so write accordingly: "
+            "one idea per bubble, 1–3 sentences each. "
+            "If the user needs a detailed answer, give the short version first "
+            "and offer to elaborate."
+        )
+        # Triggering message handle — required input for the `react` action
+        # of `send_message`, which sends an iMessage tapback. Only the current
+        # turn's handle is exposed; historical handles are not in the transcript,
+        # so the agent can only react to the message it's currently answering.
+        if context.source.message_id:
+            lines.append("")
+            lines.append("**iMessage IDs (for the `react` action of `send_message`):**")
+            lines.append(f"  - Triggering message handle: `{context.source.message_id}`")
+            lines.append(
+                "  - To tapback the user's message, call "
+                "`send_message(action='react', target='sendblue:<chat_id>', "
+                "message_handle='<handle above>', reaction='love'|'like'|'dislike'|'laugh'|'emphasize'|'question')`."
+            )
     elif context.source.platform == Platform.YUANBAO:
         lines.append("")
         lines.append(