#15148: auto-reply: add message_time and compact inbound metadata JSON

## Summary This patch improves prompt context reliability and token efficiency for structured inbound metadata: 1. Add `message_time` to `Conversation info (untrusted metadata)` so the model can see the current inbound message time in areadable, timezone-aware format. 2. Reuse envelope timestamp formatting logic for consistent timezone handling. 3. Compact JSON output for inbound metadata blocks to reduce prompt token usage. ## Problem During the prompt-shaping migration from legacy envelope lines to structured metadata blocks, the current-message timestamp was not carried over into inbound metadata. As a result, the model can lose explicit time context for the latest user turn even when `ctx.Timestamp` is available. ## Before / After Before migration (legacy envelope format, timestamp present): ```text [Telegram [User] id:123456 +5s Fri 2026-02-10 10:23 GMT+8] ``` After migration (structured metadata, current-message timestamp missing): Conversation info (untrusted metadata): ```json { "conversation_label": "[User] id:123456" } ``` After this patch (structured metadata + readable current-message time): Conversation info (untrusted metadata): ```json {"conversation_label":"[User] id:123456","message_time":"Fri 2026-02-10 10:23 GMT+8"} ``` Also in this patch, metadata JSON formatting is compacted (single-line JSON) to reduce prompt token usage. ## What Changed - `src/auto-reply/reply/inbound-meta.ts` - Added optional envelope-format options to `buildInboundUserContextPrefix(...)`. - Added `message_time` into `Conversation info (untrusted metadata)` when `ctx.Timestamp` is available. - Switched all inbound metadata JSON rendering from pretty (`JSON.stringify(..., null, 2)`) to compact (`JSON.stringify(...)`). - `src/auto-reply/reply/get-reply-run.ts` - Pass envelope formatting config (`resolveEnvelopeFormatOptions(cfg)`) into `buildInboundUserContextPrefix(...)`. - `src/auto-reply/envelope.ts` - Exported timestamp formatter as `formatEnvelopeTimestamp(...)` for shared use. - Tests - Added `src/auto-reply/reply/inbound-meta.test.ts`. - Updated `src/auto-reply/reply.raw-body.test.ts` assertions for compact JSON output. ## Behavior Notes - `message_time` is sourced from `ctx.Timestamp` only. - `message_time` respects envelope timestamp visibility config (`agents.defaults.envelopeTimestamp`), i.e. it is omitted when timestamp output is disabled. - No message interval field is added. ## AI-Assisted Transparency (Vibe-Coded) - AI-assisted: **Yes** (Codex, gpt-5.3-codex high). - Testing degree: **Fully tested** (`pnpm test` full suite passed). - Deployment validation: **Passed** in personal production deployment. - Author understanding: I reviewed and understand the implemented changes and their runtime behavior. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR updates auto-reply prompt shaping to (1) include the current inbound message timestamp in the user-role “Conversation info (untrusted metadata)” block as `message_time`, formatted using the same envelope timestamp logic and honoring `agents.defaults.envelopeTimestamp`, and (2) compact JSON rendering for inbound metadata blocks (switching from pretty-printed `JSON.stringify(..., null, 2)` to compact `JSON.stringify(...)`) to reduce prompt token usage. Changes are localized to the auto-reply prompt construction pipeline: `formatEnvelopeTimestamp` is exported from `src/auto-reply/envelope.ts` and reused by `src/auto-reply/reply/inbound-meta.ts`; `runPreparedReply` now passes resolved envelope formatting options into `buildInboundUserContextPrefix`. Tests are updated/added to assert compact JSON output and the new `message_time` behavior. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Changes are small and well-contained to prompt formatting: exporting an existing timestamp formatter, threading envelope options through one call site, and switching JSON output to compact form. Type definitions confirm `TemplateContext.Timestamp` is numeric, and repo-wide search shows no remaining references to the old private formatter name that would break builds. - No files require special attention _{Last reviewed commit: e80af47} <!-- greptile_other_comments_section --> _{(4/5) You can add custom instructions or style guidelines for the agent [here](https://app.greptile.com/review/github)!} **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->