gather: deterministic context-pack tool (aft_gather)

[iceteaSA]

gather: deterministic context-pack tool (aft_gather)

What

One new tool — aft_gather — assembles a bounded "context pack" (ranked, deduped, budgeted verbatim code evidence) in a single call. It replaces the multi-turn search → outline → zoom → callgraph read chain an agent otherwise runs to build context around a question or a symbol.

Two modes (mutually exclusive):

• question: "how does X work?" — seeds from handle_semantic_search (same pipeline as aft_search, all lanes/fallbacks)
• symbol + filePath — seeds from the callgraph (impact depth-1 callers + call_tree depth-1 callees)

Seeds expand one hop through the callgraph, dedupe by canonicalized (file, symbol) with seeds winning, and render via render_symbol_within_budget until a hard line budget (default 400, cap 800) is spent. Everything past the cut appears as one-line stubs under ## Beyond budget (zoom to expand) — nothing is silently dropped.

Why

Agents burn serial turns assembling context: search, then outline the hits, then zoom the symbols, then chase callers. Each turn round-trips through the model. A pack returns evidence (verbatim bodies with file:line headers), not conclusions — the agent reasons over it directly, ready to attach to a subagent dispatch.

Measured on a real config repo (3 questions, one call each vs. the manual chain):

• "how does the lane-verdict cache flow end-to-end" → complete 4-file chain (cache shapes, verdict logic, write/read, plugin deny hook) in one pack, used=283/400. Manual baseline: 5-6 tool calls.
• "how does score-tap decide when to write an executor row" → the full decision chain (event filter → dedup → context sources → verdict parse → DB insert) in one pack at budget=200.
• An unrehearsed cross-file question → correct core symbols plus their docstrings, first try.

Independently reproduced on the aft codebase itself: question: "how does bash output compression dispatch pick a compressor" → seeds=15, used=226/400, one pack assembling the full dispatch chain (compress → gate → compress_with_registry_exit_code 20-compressor array → Compressor trait → install path → subc mirror) that otherwise takes a 4–5-call search→zoom chain.

Honest degradation

The pack never lies about its own quality:

• While the semantic index is building, long NL queries degrade to lexical-only file-level hits. The pack renders them as visible file:line (no containing symbol) stubs and flags the header with degraded=semantic-index-building (partial results — retry when index ready) — detected via the response's semantic_status field, cleared as soon as one real seed resolves. No blocking or retry inside the tool.
• Grep-fallback hits ({file, line_text, line}, no symbol name) resolve to their containing symbol by line containment — definitions, call sites, and comment hits all upgrade to the enclosing symbol. Hits with no containing symbol stay visible as stubs.
• Unresolved external/stdlib callees collapse to one summary line ((N unresolved external calls omitted)) instead of drowning the stub list; unresolved seeds and callers are never suppressed.

Implementation

• crates/aft/src/commands/gather.rs — Rust-side composition: calls handle_semantic_search / impact_result / call_tree_result / render_symbol_within_budget directly (shared &AppContext, no bridge round-trips, no parallel reimplementation of search).
• Wiring: main.rs dispatch arm, subc_translate.rs mapping, TS factory packages/opencode-plugin/src/tools/gather.ts + registration (same tier as aft_callgraph — depends on the callgraph store).
• No new dependencies, no config surface beyond the tool args, no LLM calls, no caching.
• Follows the tri-state honest-reporting convention (protocol.rs Response doc-comment): success:false+code for un-performable calls (e.g. invalid_request on a bad mode combo), success:true with a visible degraded/stub pack for partial results — never a bare empty success.

Tests

22 unit tests in gather.rs, including red-checked regressions (each confirmed to fail against pre-fix code): mid-codepoint truncation panic, duplicate-symbol line-anchored resolution, abs/rel path dedupe, containing-symbol resolution via a real TreeSitterProvider, callee-only stub suppression driven through the production build_pack path, and degradation-flag presence/absence/mixed cases.

Limitations (deliberate scope)

• 1-hop expansion only — multi-hop was deliberately excluded: the budget math and ranking get harder and the packs get noisier.
• Callgraph-dependent by design: neighbor expansion quality follows the callgraph store's freshness, same as aft_callgraph.
• Budget counted in lines, not tokens — matches aft's existing budget idiom across zoom/outline.

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Summary by cubic

Adds aft_gather_context, a single-call, deterministic context-pack builder that returns ranked, deduped, verbatim code within a fixed line budget, replacing the multi-step search→outline→zoom→callgraph chain. Exposed as gather in Rust and aft_gather_context in @opencode on the “all” surface.

• New Features

  • Two modes (XOR): question (semantic seeds) or symbol+path (impact callers + call-tree callees); 1-hop expansion with (file, symbol) dedupe and seeds winning.
  • Hard line budget (default 400, max 800) with per-symbol balancing; overflow listed under “Beyond budget”; exact used lines computed post-render.
  • Grep-fallback hits resolve to containing symbols; no-symbol hits render as visible stubs.
  • Honest header flags: degraded=semantic-index-building and neighbors=skipped(callgraph-unavailable).
  • Registered in @opencode with XOR schema validation and path→filePath mapping; covered by a transport-invariance test; gated to the “all” surface.

• Bug Fixes

  • Path normalization/dedupe: absolute vs. relative paths dedupe on Windows; a literal backslash in Unix filenames normalizes to / and renders a clean “file not found” stub.

^{Written for commit 5eb5870. Summary will update on new commits.}

Greptile Summary

This PR introduces aft_gather_context, a single-call deterministic context-pack builder that replaces the multi-turn search→outline→zoom→callgraph chain. It seeds from semantic search (question mode) or callgraph impact/call-tree (symbol mode), expands 1 hop, deduplicates by (file, symbol), renders verbatim code within a hard line budget, and lists overrun candidates as visible stubs.

• gather.rs (Rust): composition layer calling handle_semantic_search, impact_result, call_tree_result, and render_symbol_within_budget; includes 22 unit tests covering mid-codepoint truncation, abs/rel path dedupe, callee suppression, and degradation flag behavior.
• gather.ts (TypeScript): tool definition with XOR schema validation, path→filePath transport rename, and budget coercion; verified by a transport-invariance test.
• Wiring: main.rs dispatch arm, subc_translate.rs mapping with path resolution, tool-registration.ts registration gated to the "all" surface (same tier as aft_callgraph).

Confidence Score: 4/5

• Safe to merge after fixing one defect in collect_callgraph_neighbors
• In question mode, the impact_result call inside collect_callgraph_neighbors hardcodes false for include_tests instead of forwarding the caller-supplied value. When an agent passes includeTests: true, test-file callers are silently excluded from the neighbor list while callees are correctly included — an asymmetry that makes the flag partially ineffective. Symbol mode is unaffected (it calls impact_result with the correct value). Everything else — deduplication, budget accounting, stub rendering, path normalization, degradation flags, and transport wiring — is well-implemented and thoroughly tested.
• crates/aft/src/commands/gather.rs — specifically the impact_result call inside collect_callgraph_neighbors

Important Files Changed

Filename	Overview
crates/aft/src/commands/gather.rs	New gather.rs command (1660 lines): implements two-mode context-pack builder with semantic search seeding, 1-hop callgraph expansion, per-symbol budgeting, and deduplication. One confirmed defect: include_tests is hardcoded to false in collect_callgraph_neighbors for the impact_result (callers) path, causing includeTests: true to be silently ignored for test callers in question mode while callees are correctly filtered. Symbol mode is unaffected. 22 unit tests cover regressions thoroughly.
packages/opencode-plugin/src/tools/gather.ts	TypeScript tool definition for aft_gather_context. Correctly handles path→filePath mapping, XOR mode validation, budget coercion, and error propagation. Transport invariance is verified by a dedicated test.
crates/aft/src/subc_translate.rs	Adds translate_gather with XOR validation, filePath resolution against project root, and allowlist registration. Tests cover path resolution and includeTests passthrough.
packages/opencode-plugin/src/tool-registration.ts	Registers aft_gather_context in ALL_ONLY_TOOLS (surface-gated) and adds gatherTools spread; wiring is consistent with aft_callgraph's pattern.
crates/aft/src/main.rs	One-line dispatch arm added for "gather" → handle_gather. Straightforward wiring, no issues.
packages/opencode-plugin/src/tests/tool-surface-transport-invariant.test.ts	Adds transport invariance test for aft_gather_context verifying path→filePath mapping and that the internal transport key is not exposed in the schema. Well-structured.

Sequence Diagram

sequenceDiagram
    participant Agent
    participant TS as gather.ts
    participant Translate as subc_translate
    participant Rust as gather.rs
    participant Search as semantic_search
    participant CG as Callgraph Store

    Agent->>TS: aft_gather_context with question or symbol+path
    TS->>TS: XOR mode validation and path to filePath rename
    TS->>Translate: toolCall gather with filePath
    Translate->>Translate: XOR validation and resolve filePath from project root
    Translate->>Rust: RawRequest command gather

    alt question mode
        Rust->>Search: "handle_semantic_search query top_k=15"
        Search-->>Rust: results with symbol seeds and grep-fallback hits
        Rust->>Rust: resolve_containing_symbol for grep-fallback hits
        Rust->>Rust: sort seeds by score and assign seed_ordinal
        Rust->>CG: collect_callgraph_neighbors 1-hop callers and callees
        CG-->>Rust: neighbor candidates
    else symbol mode
        Rust->>CG: "impact_result callers depth=1"
        CG-->>Rust: callers
        Rust->>CG: "call_tree_result callees depth=1"
        CG-->>Rust: callees
    end

    Rust->>Rust: dedupe by file+name with seeds winning
    Rust->>Rust: build_pack render each candidate within per_symbol_budget
    Rust->>Rust: build header with exact used count and append stubs
    Rust-->>TS: text with gather pack and verbatim bodies
    TS-->>Agent: context pack string

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_{Reviews (23): Last reviewed commit: "gather: deterministic context-pack tool ..." | Re-trigger Greptile}

[cubic-dev-ai]

4 issues found across 7 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[iceteaSA]

Follow-up on the two maintainability notes from the Greptile summary (they weren't separate review threads, so noting here) — both addressed in cf09b9b9:

• degraded expression flagged as always-false in the non-empty-seeds path — intentional: degraded only applies when zero symbol-level seeds resolve (a building index yields no seeds; a ready index with seeds is never degraded). Logic unchanged; added a comment on the why so it doesn't read as dead code.
• callee-suppression string-match coupling — extracted UNRESOLVED_MARKER ("(symbol not resolved)") and CALLEE_PROVENANCE_PREFIX ("callee-of-") consts, referenced by both the producer (render_symbol_section err arm / collect_callees_for_seed) and the consumer (build_pack suppression guard) so the match can't silently drift. Only test-site literals remain, intentionally — a test pointing at the const couldn't catch const drift.

Matched/rendered text is byte-identical; 23/23 gather tests green.

[iceteaSA]

Rebased onto current main (690bed59) and renamed the tool to aft_gather_context — the longer name reads more clearly at the call site.

The rename covers the advertised tool name and the agent-facing error strings only. The wire command stays "gather" (TS→Rust transport), as do the file and function names, matching how aft_callgraph maps to callers/call_tree/impact from navigation.ts. Both manifest entries were updated: the REG-V049-OC-ALL set and the HOSTONLY-V049-006 allowlist row.

Rebase conflicts were confined to ARCHITECTURE.md and STRUCTURE.md; all code auto-merged. tools/structure.ts and tools/lsp.ts are gone from main, so I kept your shorter tool lists and only re-inserted gather.ts.

Verified: registration-parity 10, tool-surface-transport-invariant 2, tools 10, cargo test gather 23, bun run build and cargo build clean. The built bundle contains aft_gather_context and zero occurrences of the old name.

Still one commit. Two notes on the full plugin suite, both pre-existing on main rather than from this branch: the two e2e outline command failures and the format_on_edit ones. main's own CI is currently red on 1d1a6968, 1da22bfe, and ef57355f, and 690bed59's run was cancelled — happy to hold this until that's sorted if you'd rather rebase onto a green base.

[iceteaSA]

Opened #192 to ask the design question separately from the diff: whether you want one-call context packs in aft at all, and in what shape. Answer there and I'll rework this to match — or close it if the answer is no.

Current state here: green on a4b6aaee, 14/14 including the Windows jobs, still one commit.

[iceteaSA]

Rebased onto v0.49.3 (0dbcb541). Clean rebase, still one commit, now 500f1a9a. Regenerated the four governed manifests for the new base.

CI: 13 green, one red — E2E / E2E (Windows native). I believe it's an infra flake, not the diff, and here's the evidence rather than an assertion.

Scenario 1's opencode run timed out at 90s and the process was stopped. The whole S1 failure set follows from that one timeout:

(opencode run timed out at 90s -- stopping process)
PASS [plugin loaded]
FAIL [bridge spawned]
WARN [search index started (non-blocking)]
FAIL [aimock received chat-completion requests]
Results: 23 passed, 2 failed

plugin loaded passes (the plugin resolved and started) but bridge spawned fails because started, pid never reaches the log — the run was killed before the bridge finished spawning. aimock received chat-completion requests fails for the same reason: opencode never got far enough to talk to the mock. The journal confirms it — 13 requests total, all with S2 timestamps, none from S1.

Same job, same assertions, on the two nearest green runs:

• a4b6aaee (this branch, previous sha): PASS [bridge spawned], PASS [aimock received…], 26 passed / 0 failed, no timeout line
• 0dbcb541 (your main, the base I just rebased onto): identical, 26 / 0, no timeout line

So the same code path passes on the parent commit and on the previous revision of this branch. The delta between them is a 90s wall clock on a cold Windows runner, not the diff — nothing in this change is reachable from bridge spawn or plugin boot. Unit / Cargo test (Windows), Cargo check deny-warnings (Windows), and Bash permission e2e (Windows) are all green on this sha.

I can't re-run it — gh run rerun returns Must have admin rights to Repository. Could you kick that one job? If you'd rather I force-push an empty amend to retrigger the whole suite, say so and I will, but that burns a full round on all 14 jobs to retry one.

Separately: #192 asks whether you want this capability at all, which is the more useful question than another rebase.

[iceteaSA]

Rebased onto 2a2b4f2d and green — ignore the re-run request above, the Windows E2E failure was the flake I described and it cleared on its own.

9bb5af30, still one commit. 14/14 checks pass, E2E / E2E (Windows native) included: PASS [bridge spawned], PASS [aimock received chat-completion requests], 26 passed / 0 failed, no 90s timeout line. That's the same job that failed on the previous sha with the same code in it, which settles the question of whether the diff was involved.

The four new commits didn't touch any file this branch touches, so the rebase was clean and only the governed manifests needed regenerating for the new base.