feat: title new sessions from _meta.sessionTitle - #920
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ACP clients that manage their own session naming had no harness-neutral way to name a Claude Code session; only the SDK-shaped `_meta.claudeCode.options.title` spelling worked, which every other harness would have to special-case. Map the neutral `_meta.sessionTitle` onto the SDK's `Options.title` so one wire contract works across adapters. The SDK-shaped spelling still wins when both are supplied — it is the more specific request and already-released behavior. Applied only when creating or forking, since the SDK ignores `title` on resume, and reused the adapter's existing `sanitizeTitle` so there is one title contract. Co-authored-by: Will Pfleger <pfleger.will@gmail.com> Signed-off-by: Will Pfleger <pfleger.will@gmail.com>
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ACP harnesses that name a session from the first text they receive all land in the same place: every managed Buzz agent opens with the identical `[Base] You are operating inside the Buzz platform…` framing, so the harness session list shows a wall of indistinguishable rows. Because sessions are keyed per channel, one agent active in several channels produces several of them. This sends the name out of band instead. `session/new` carries `_meta.sessionTitle` with `Agent · #channel`, composed from the agent's `display_name` (or its unique `name` handle) and the channel it is serving. The prompt is untouched — no tokens spent, no perturbation of the prompt contract, and nothing new for the desktop observer's section parsing to handle. The mechanism is harness-agnostic: Buzz sends the field on every ACP `session/new` regardless of which harness is behind it, and adapters that don't read it ignore it per spec. ## Inert until a consuming adapter ships ACP adapters ignore `_meta` members they do not recognize, so against an adapter with no reader a Buzz session gets no title and nothing else changes. Three adapter halves consume it — Codex, Goose, and Claude Code (linked below); this half and each reader are only useful together, and each reader lands independently. No version floor is added. `codex_adapter_is_outdated_with_path` already gates codex-acp on major version `>= 1` (`desktop/src-tauri/src/managed_agents/discovery.rs:1276-1284`) and this feature needs nothing above that — an older adapter is not broken by the extra member, it simply ignores it. ## What changes **`crates/buzz-acp`** owns sanitization and composition. `sanitize_session_title` collapses whitespace, drops control characters, and caps at `SESSION_TITLE_MAX_CHARS` (80) by character, not byte, so a multi-byte character cannot be split. `compose_session_title` truncates only the channel part against that cap, so the agent name always survives; when the agent name alone fills the cap the channel is dropped rather than the name. `session_new_full` sets `_meta.sessionTitle` when a title exists and omits `_meta` entirely when it does not, since an adapter may distinguish an absent member from a null one. **`desktop/src-tauri`** only resolves and exports. `resolve_session_title` picks `display_name` or falls back to `name`, and `spawn_agent_child` writes it to `BUZZ_ACP_SESSION_TITLE` — or removes the variable when neither candidate yields anything printable. DMs, unresolved channels, and heartbeat sessions get the bare agent name with no channel suffix. ## Four properties that are easy to remove by accident **Control characters are stripped at the desktop boundary, not in the harness.** An interior NUL cannot cross the environment boundary at all — `Command::env` fails the entire spawn rather than passing it through. Deferring the strip to `buzz-acp` would let a corrupted display name turn display chrome into a spawn failure. A display name that is *only* control characters falls back to `name`. **The title is hashed into `spawn_config_hash`.** Without it, renaming an agent left the running process with a stale title and no restart badge. The hash runs the same `resolve_session_title` the spawn writes, and skips it when a user env override shadows `BUZZ_ACP_SESSION_TITLE` — spawn writes the title *before* the layered user env, so the override is what actually runs, and it already reaches the hash through `descriptor.env`. Hashing the record-derived value under an override would badge a rename that changes nothing. **One channel resolve serves both consumers.** `resolve_new_session_channel_context` returns `(is_dm, title_channel)` from a single metadata lookup, feeding both the canvas block's DM check and the title. `ChannelInfoResolver` caches only `Some`, so two independent calls against an unresolvable channel pay the full `fetch_channel_info` retry sequence twice — two timeouts plus a retry delay each — directly in front of `session/new`, precisely when the relay is already degraded. **The `"unknown"` channel name is treated as absent.** `fetch_channel_info` substitutes the literal `"unknown"` for a metadata event with no `name` tag. Composing that sentinel would title every unnamed channel `Agent · #unknown`, reintroducing the exact collision the suffix exists to remove while naming a channel something it isn't. The startup cache already refuses `channel_type == "unknown"` for the same reason. Closes #2334 Related — the adapter halves that consume `_meta.sessionTitle`: - [codex-acp#338](agentclientprotocol/codex-acp#338) — Codex - [aaif-goose/goose#10712](aaif-goose/goose#10712) — Goose - [claude-agent-acp#920](agentclientprotocol/claude-agent-acp#920) — Claude Code --------- Signed-off-by: Will Pfleger <pfleger.will@gmail.com>
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An ACP client that spawns several sessions against one agent has no harness-neutral way to label them. The SDK-shaped
_meta.claudeCode.options.titlealready reachesOptions.titlethrough the...userProvidedOptionsspread, but that spelling is Claude-specific — a client driving Claude Code alongside other ACP agents has to special-case it. This maps the neutral_meta.sessionTitleonto the same SDK option so one wire contract works across adapters.Options.titleis the SDK's own creation affordance: the CLI persists it as acustom-titleentry and sets its auto-title suppression latch, so the title survives the first turn instead of being replaced by the generated summary. Nothing downstream needs to change —maybeUpdateSessionTitlealready preferscustomTitleoversummary, so the turn-endsession_info_updatecarries the client's title verbatim.Behavior
_meta.sessionTitle_meta.claudeCode.options.titleoptions.title"Fix the login bug""Fix the login bug""harness-neutral""sdk-shaped""sdk-shaped"null/ non-string / blankuserProvidedOptions?.title ?? sanitizedSessionTitle, applied after the spread.resume === undefined || forkSession === truepredicate the adapter already uses to allocateoptions.sessionId. The SDK ignorestitleon resume regardless, but gating makes the contract explicit.sanitizeTitleis reused as-is, so client titles obey the same whitespace and 256-character contract as SDK summaries rather than acquiring a second title contract. A title that sanitizes to empty is omitted, letting the SDK auto-generate instead of receiving an empty string._metareads in this file treat malformed input.Related
_meta.sessionTitlecontract for Codex_meta.sessionTitleon everysession/new