refactor: remove unused cross-agent-comms subsystem

Nothing used the cross-agent message system (send/recv/watch/status/discover/halt/resume over the inbox/from-agents/ file-IPC protocol). Every cross-project handoff goes through inbox-send instead. I removed the scripts, READMEs, workflow, tests, INDEX entry, the three startup.org wirings, and the legacy bin symlinks, then repointed helper-mode's escalation to inbox-send and noted the removal in the generic-agent-runtime spec.

1 files changed, 0 insertions, 218 deletions

diff --git a/.ai/scripts/cross-agent-comms/cross-agent-recv.md b/.ai/scripts/cross-agent-comms/cross-agent-recv.md
deleted file mode 100644
index 247a27a..0000000
--- a/.ai/scripts/cross-agent-comms/cross-agent-recv.md
+++ /dev/null
@@ -1,218 +0,0 @@
-# cross-agent-recv
-
-**Purpose.** The canonical receiver-side processor. Reads a single incoming
-message file and reports a structured decision the agent acts on:
-process / dedup / query / reject.
-
-The script handles only mechanical checks (frontmatter, signature, dedup,
-version, tools). Substance-level decisions like `pushback` ("I disagree with
-this request") happen one layer up — after the agent reads the message body
-the script returns as `process`-able.
-
-This is the read-side counterpart to `cross-agent-send`. Together they are the
-two halves of the per-message contract. The agent's polling loop calls
-`cross-agent-recv` on every new file in `inbox/from-agents/` and dispatches on
-the decision.
-
-Without this script, every receiver implementation re-invents GPG verify +
-frontmatter sanity-check + SHA-256 dedup. With it, behavior is consistent
-across projects.
-
-## Usage
-
-```
-cross-agent-recv <message-file>
-```
-
-Single positional argument: a `.org` file in `inbox/from-agents/`. The matching
-`.asc` signature file must be present alongside it.
-
-### Flags
-
-| Flag | Default | Purpose |
-|---|---|---|
-| `--no-verify` | (verify on) | Skip GPG verification. Testing only. |
-| `--no-dedup` | (dedup on) | Skip SHA-256 dedup against existing files. Testing only. |
-| `--protocol-version <N>` | 5 | Override the expected protocol version. Useful for testing forward-compatibility checks. |
-| `--json` | off | Output decision as JSON for easier parsing by the agent. |
-
-## Behavior
-
-Runs the receiver checks in order. First failure determines the decision.
-
-### Step 1 — Frontmatter sanity-check
-
-Parse the message's org-mode frontmatter. Required fields:
-
-- `#+TITLE`
-- `#+CONVERSATION_ID`
-- `#+MESSAGE_TYPE` (must be one of: `request`, `progress`, `query`, `pushback`,
-  `complete`, `release`, `escalate`)
-- `#+SEQUENCE` (integer)
-- `#+TIMESTAMP` (ISO 8601 with explicit offset)
-- `#+PROTOCOL_VERSION` (must match the expected version; default 5)
-
-Any required field missing, malformed, or the protocol version mismatched →
-decision = `reject` (frontmatter) or `query` (version mismatch — see below).
-
-### Step 2 — Protocol-version check
-
-If `PROTOCOL_VERSION` doesn't match the expected:
-
-- Decision = `query`. Action: receiver should write a `query` reply asking the
-  sender to upgrade to the expected protocol version.
-
-### Step 3 — Signature verification
-
-Look for `<message-file>.asc` alongside the `.org`. If missing or `gpg
---verify` fails:
-
-- Decision = `reject` (signature). Surface to user; do not act.
-
-The `.asc` file MUST be present when the `.org` is — `cross-agent-send`
-guarantees this with its strict ordering (`.asc` lands first). If the `.asc`
-is missing despite the `.org` being present, the sender violated atomic-write
-ordering or the file was tampered with in transit.
-
-### Step 4 — SHA-256 dedup
-
-Compute SHA-256 of the message file. Scan the same directory for existing
-files matching `CONVERSATION_ID + SEQUENCE`:
-
-- No match → decision = `process` (new message, dispatch by type).
-- Match with **identical** SHA-256 → decision = `dedup` (silent retry; do not
-  reprocess).
-- Match with **different** SHA-256 → decision = `process` (sequence collision
-  with non-identical content; both are legitimate, ordered by `#+TIMESTAMP`).
-
-### Step 5 — REQUIRES_TOOLS optional check
-
-If the message has a `#+REQUIRES_TOOLS` field, verify each named tool/MCP is
-available in the receiver's environment.
-
-- All available → `process`.
-- One or more missing → decision = `query`. The agent should write a `query`
-  reply naming the missing tools, asking the sender to reframe the request to
-  avoid them.
-
-### Step 6 — Dispatch decision
-
-If all checks pass, decision = `process` with the parsed `MESSAGE_TYPE` so the
-agent's main loop knows which handler to invoke.
-
-## Output
-
-### Default (human-readable)
-
-```
-$ cross-agent-recv inbox/from-agents/20260427T091015Z-from-homelab-prep-fixup.org
-decision: process
-message_type: request
-conversation_id: prep-fixup
-sequence: 6
-sha256: a1b2c3d4...
-```
-
-### `--json`
-
-```json
-{
-  "decision": "process",
-  "reason": null,
-  "message_type": "request",
-  "conversation_id": "prep-fixup",
-  "sequence": 6,
-  "timestamp": "2026-04-27T04:11:42-05:00",
-  "sha256": "a1b2c3d4..."
-}
-```
-
-For decisions other than `process`, `reason` carries a human-readable
-explanation:
-
-```json
-{
-  "decision": "query",
-  "reason": "PROTOCOL_VERSION mismatch: expected 5, got 4",
-  "conversation_id": "prep-fixup",
-  "sequence": 6
-}
-```
-
-## Decision exit codes
-
-| Decision | Exit code | Agent action |
-|---|---|---|
-| `process` | 0 | Dispatch to the message-type handler |
-| `dedup` | 1 | Silent — do nothing further |
-| `query` | 2 | Write a `query` reply (see `reason` for what to ask) |
-| `reject` | 3 | Surface to user; do not auto-reply |
-
-The agent reads stdout/JSON to learn the decision; it can also key off exit
-code for simpler bash-style dispatching.
-
-## Failure modes
-
-| Symptom | Cause | Fix |
-|---|---|---|
-| `decision: reject (frontmatter)` | Required field missing or malformed | Open the message; fix or surface to user. The sender should not have produced this file. |
-| `decision: reject (signature)` | `.asc` missing, GPG verify failed, or signer unknown | Check that `.asc` exists alongside `.org`. If yes, run `gpg --verify <msg>.asc <msg>` manually for diagnostic output. |
-| `decision: query (PROTOCOL_VERSION)` | Sender on older/newer protocol | Reply with a `query` asking sender to upgrade. Both sides should align before continuing. |
-| `decision: query (REQUIRES_TOOLS)` | Receiver lacks one of the named tools | Reply with a `query` naming the missing tools; sender should reframe to avoid. |
-| `decision: dedup` | Already-processed identical retry | No action. The script handled it correctly. |
-
-## HALT awareness
-
-Checks `~/.config/cross-agent-comms/HALT` at the start of every invocation. If
-HALT exists, exits with code 5 ("halt active; remove
-~/.config/cross-agent-comms/HALT to resume") without verifying, deduping, or
-returning a decision.
-
-**The inbound file is left in place** — not moved, not rejected, not
-deduped. When HALT clears and polling resumes, the file gets picked up via
-the normal cold-start handling (whichever surfaces first: watcher
-notification, startup workflow check, or the next agent poll). Reversibility
-is preserved.
-
-If the HALT file exists but is unreadable, fail-closed — treat as if HALT is
-set.
-
-See `cross-agent-halt.md` for the full halt mechanism.
-
-## Examples
-
-```bash
-# Basic invocation in an agent's polling loop
-for msg in inbox/from-agents/*.org; do
-  decision=$(cross-agent-recv --json "$msg")
-  case "$(echo "$decision" | jq -r '.decision')" in
-    process) handle_message "$msg" ;;
-    dedup)   ;;  # silent
-    query)   write_query_reply "$msg" "$decision" ;;
-    reject)  surface_to_user "$msg" "$decision" ;;
-  esac
-done
-
-# Test signature verification only
-cross-agent-recv --no-dedup inbox/from-agents/test-msg.org
-
-# Test against a future protocol version
-cross-agent-recv --protocol-version 6 inbox/from-agents/future-msg.org
-```
-
-## Performance
-
-The script is fast (single SHA-256 compute, single GPG verify, frontmatter
-parse). For typical messages (single-digit KB), runs in well under 100ms.
-Dedup-scan is O(N) over files in the directory; if a project's
-`inbox/from-agents/` accumulates hundreds of files, archive released
-conversations to keep the scan fast.
-
-## See also
-
-- `cross-agent-send` — counterpart writer.
-- `cross-agent-watch` — fires when a new message arrives; agent then calls
-  `cross-agent-recv` to process it.
-- `cross-agent-status` — pending-message snapshot (uses similar
-  released-vs-unreleased logic, but doesn't process individual messages).
-- `cross-agent-comms.org` — protocol spec, the "what" the script implements.