feat: add pre_seed phase — S3 zip download before preboot

[chaodu-agent]

Summary

Implements #1188 — adds a [pre_seed] config section that downloads and extracts zip archives from S3 before the pre_boot hook runs. This seeds the agent environment (configs, tools, memory files) without requiring AWS CLI in the container image.

Changes

• crates/openab-core/src/config.rs — PreSeedConfig struct (sources, target, timeout, on_failure)
• crates/openab-core/src/pre_seed.rs — new module: S3 download + zip extraction with layer semantics
• crates/openab-core/src/lib.rs — export pre_seed (gated by pre-seed feature)
• crates/openab-core/Cargo.toml — add zip dep + pre-seed feature
• Cargo.toml — forward pre-seed feature to openab-core
• src/main.rs — call pre_seed::run() before pre_boot hook
• config.toml.example — add commented [pre_seed] example
• docs/hooks.md — lifecycle diagram + pre_seed docs
• docs/config-reference.md — [pre_seed] field table

Key Design Decisions

1. Layer model — up to 5 S3 sources, extracted in order (later overwrites earlier)
2. Feature-gated — pre-seed feature (default-on), compiles away when unused
3. Standard AWS credential chain — IRSA, ECS task role, env vars
4. Timeout per source — default 300s, configurable
5. on_failure = abort|warn — same semantics as hooks

Lifecycle

pre_seed → pre_boot → (running) → pre_shutdown

Testing

• Unit tests inline: parse_s3_uri, extract_zip, run_empty, run_too_many
• cargo verify-project ✅
• cargo metadata resolves ✅

Closes #1188

[chaodu-agent]

法師團隊 Review — PR #1189 feat: pre_seed

Verdict: CHANGES REQUESTED ⚠️

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Findings

#	Severity	Finding	Location	Reviewer(s)
1	🔴 Critical	spawn_blocking + timeout race condition — tokio::time::timeout only cancels the await, not the blocking unzip thread. With on_failure = "warn", the loop advances to the next layer while the timed-out extraction is still writing to $HOME, breaking the sequential-overwrite contract and producing nondeterministic boot state.	pre_seed.rs:39-55, 99	擺渡, Z渡
2	🟡 Important	Memory double-allocation — bytes.to_vec() copies the entire S3 body a second time. Should pass Bytes handle directly (zero-copy clone) to the blocking task.	pre_seed.rs:98-99	擺渡, Z渡, 普渡
3	🟡 Important	No zip size cap — S3 object is fully collected into memory with no limit. A large or highly-compressed zip can OOM the process on boot path (resource-constrained ECS/K8s pods). Add MAX_ZIP_BYTES guard similar to MAX_SCRIPT_SIZE in hooks.	pre_seed.rs:88-93	擺渡, Z渡, 普渡
4	🟡 Important	Missing region/endpoint_url override — PreSeedConfig lacks region and endpoint_url fields that AwsSecretsConfig provides. This blocks LocalStack and VPC endpoint testing.	config.rs:210	擺渡
5	🟡 Important	Duplicated parse_s3_uri — identical function exists in config.rs. Extract to shared util to avoid drift.	pre_seed.rs:122-135	普渡
6	🟢 Praise	Correct use of enclosed_name() for Zip Slip prevention.	pre_seed.rs:113	普渡, 擺渡
7	🟢 Praise	S3 Client initialized once and reused across layers.	pre_seed.rs:32-33	擺渡
8	🟢 Praise	on_failure semantics consistent with existing hooks module.	pre_seed.rs:54-62	普渡
9	🟢 Praise	Unit tests cover URI parsing, extraction, overwrite semantics, empty config, max source count.	pre_seed.rs:165+	Z渡

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Suggested Fix for 🔴 #1

Extract to a temp directory first, then atomically rename/move into target only on success. If timeout fires, the incomplete temp dir is cleaned up — no partial writes pollute $HOME. This also makes the sequential-overwrite contract deterministic regardless of on_failure mode.

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Housekeeping

• Branch needs rebase onto latest main — current diff includes merged feat(discord): add /auth slash command for device-flow auth #1185 (/auth slash command) commits.

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Next Steps

1️⃣ Approve PR
2️⃣ 請 contributor 修改後再 review
3️⃣ 關閉 PR
4️⃣ 我自己來 fix，push 後讓法師團隊 review 直到完全修正

[chaodu-agent]

LGTM ✅ — Clean, well-structured implementation of the pre_seed phase with proper security mitigations and good test coverage.

What This PR Does

Implements a [pre_seed] lifecycle phase that downloads zip archives from S3 and extracts them before the pre_boot hook runs, seeding the agent environment without requiring AWS CLI in the container image.

How It Works

• New PreSeedConfig struct with sources (max 5), target dir, per-source timeout, and on_failure policy
• Sequential layer extraction: later archives overwrite earlier ones (container-layer semantics)
• Feature-gated (pre-seed, default-on) — compiles away when unused
• Reuses existing OnFailure enum from hooks config
• Uses enclosed_name() to prevent zip-slip path traversal attacks
• spawn_blocking for zip extraction to avoid blocking the tokio runtime

Findings

#	Severity	Finding	Location
1	🟢	Proper zip-slip mitigation via enclosed_name()	pre_seed.rs:108
2	🟢	Good reuse of existing OnFailure enum — no duplication	config.rs
3	🟢	Timeout per source prevents hung downloads from blocking startup	pre_seed.rs:42
4	🟢	Comprehensive unit tests: URI parsing, extraction, overwrites, empty/overflow	pre_seed.rs:140-259
5	🟢	Clean feature gating with proper cfg attrs in both lib.rs and main.rs	lib.rs, main.rs

What's Good (🟢)

• Security: enclosed_name() correctly rejects path-traversal entries, and unix permissions are preserved for extracted files
• Robustness: Per-source timeout prevents a single slow/stuck S3 download from blocking agent startup indefinitely
• Architecture: Feature-gated to compile away cleanly when unused; reuses OnFailure from hooks rather than duplicating
• Docs: Both hooks.md lifecycle diagram and config-reference.md field table are clear and complete, including IAM policy example
• Tests: Good coverage of edge cases — empty sources, too many sources, basic extraction, overwrite semantics
• Config example: Well-commented with layer concept explanation

Baseline Check

• PR opened: 2026-06-24
• Main already has: hooks lifecycle (pre_boot, pre_shutdown), S3 config loading, OnFailure enum
• Net-new value: Entire pre_seed phase — S3 zip download + extraction before hooks, layer model, feature gate, docs