feat(gmail): add +reply, +reply-all, and +forward helpers

[HeroSizy]

Description

Closes #88 — adds first-class reply and forward support to the Gmail CLI helpers.

• +reply — Reply to a message by ID. Automatically fetches the original message, sets In-Reply-To, References, and threadId headers, quotes the original, and sends via users.messages.send.
• +reply-all — Same as +reply but addresses all original To/CC recipients. Supports --remove to drop recipients and --cc to add new ones.
• +forward — Forward a message to new recipients with a standard forwarded-message block (From, Date, Subject, To, Cc). Supports optional --body for a note above the forwarded content.

All three commands support --dry-run for safe previewing (works without auth credentials).

Address handling details:

• Prefers Reply-To over From when selecting reply recipients (mailing lists, support systems)
• Parses multi-address Reply-To headers (e.g., list@example.com, owner@example.com) and deduplicates CC against the full set
• Uses RFC 5322-aware mailbox list parsing — commas inside quoted display names (e.g., "Doe, John" <john@example.com>) are handled correctly
• Uses exact normalized email extraction (not substring matching) for --remove filtering and sender exclusion — e.g., removing ann@example.com does not affect joann@example.com
• Case-insensitive email comparison throughout

Known limitation: +forward currently forwards the message text/snippet only. Full MIME forwarding with attachments will be addressed in a follow-up PR (ref #88).

New files

File	Purpose
src/helpers/gmail/reply.rs	+reply and +reply-all logic, message metadata fetching, RFC 2822 header construction
src/helpers/gmail/forward.rs	+forward logic, forwarded message formatting

Modified files

File	Change
src/helpers/gmail/mod.rs	Register new modules, inject +reply/+reply-all/+forward subcommands, add handler dispatch

Dry Run Output:

+reply:

$ gws gmail +reply --message-id 18f1a2b3c4d --body "Thanks, got it!" --dry-run
{
  "body": {
    "raw": "VG86IHNlbmRlckBleGFtcGxlLmNvbQ0KU3ViamVjdDogUmU6IE9yaWdpbmFsIHN1YmplY3QNCkluLVJlcGx5LVRvOiA8MThmMWEyYjNjNGRAZXhhbXBsZS5jb20-DQpSZWZlcmVuY2VzOiA8MThmMWEyYjNjNGRAZXhhbXBsZS5jb20-DQoNClRoYW5rcywgZ290IGl0IQ0KDQpPbiBUaHUsIDEgSmFuIDIwMjYgMDA6MDA6MDAgKzAwMDAsIHNlbmRlckBleGFtcGxlLmNvbSB3cm90ZToKPiBPcmlnaW5hbCBtZXNzYWdlIGJvZHk=",
    "threadId": "thread-18f1a2b3c4d"
  },
  "dry_run": true,
  "is_multipart_upload": false,
  "method": "POST",
  "query_params": {},
  "url": "https://gmail.googleapis.com/gmail/v1/users/me/messages/send"
}

+reply-all:

$ gws gmail +reply-all --message-id 18f1a2b3c4d --body "Sounds good!" --cc eve@example.com --remove bob@example.com --dry-run
{
  "body": {
    "raw": "VG86IHNlbmRlckBleGFtcGxlLmNvbQ0KU3ViamVjdDogUmU6IE9yaWdpbmFsIHN1YmplY3QNCkluLVJlcGx5LVRvOiA8MThmMWEyYjNjNGRAZXhhbXBsZS5jb20-DQpSZWZlcmVuY2VzOiA8MThmMWEyYjNjNGRAZXhhbXBsZS5jb20-DQpDYzogeW91QGV4YW1wbGUuY29tLCBldmVAZXhhbXBsZS5jb20NCg0KU291bmRzIGdvb2QhDQoNCk9uIFRodSwgMSBKYW4gMjAyNiAwMDowMDowMCArMDAwMCwgc2VuZGVyQGV4YW1wbGUuY29tIHdyb3RlOgo-IE9yaWdpbmFsIG1lc3NhZ2UgYm9keQ==",
    "threadId": "thread-18f1a2b3c4d"
  },
  "dry_run": true,
  "is_multipart_upload": false,
  "method": "POST",
  "query_params": {},
  "url": "https://gmail.googleapis.com/gmail/v1/users/me/messages/send"
}

+forward:

$ gws gmail +forward --message-id 18f1a2b3c4d --to dave@example.com --body "FYI see below" --cc carol@example.com --dry-run
{
  "body": {
    "raw": "VG86IGRhdmVAZXhhbXBsZS5jb20NClN1YmplY3Q6IEZ3ZDogT3JpZ2luYWwgc3ViamVjdA0KQ2M6IGNhcm9sQGV4YW1wbGUuY29tDQoNCkZZSSBzZWUgYmVsb3cNCg0KLS0tLS0tLS0tLSBGb3J3YXJkZWQgbWVzc2FnZSAtLS0tLS0tLS0KRnJvbTogc2VuZGVyQGV4YW1wbGUuY29tCkRhdGU6IFRodSwgMSBKYW4gMjAyNiAwMDowMDowMCArMDAwMApTdWJqZWN0OiBPcmlnaW5hbCBzdWJqZWN0ClRvOiB5b3VAZXhhbXBsZS5jb20KT3JpZ2luYWwgbWVzc2FnZSBib2R5Ci0tLS0tLS0tLS0=",
    "threadId": "thread-18f1a2b3c4d"
  },
  "dry_run": true,
  "is_multipart_upload": false,
  "method": "POST",
  "query_params": {},
  "url": "https://gmail.googleapis.com/gmail/v1/users/me/messages/send"
}

Checklist:

• My code follows the AGENTS.md guidelines (no generated google-* crates).
• I have run cargo fmt --all to format the code perfectly.
• I have run cargo clippy -- -D warnings and resolved all warnings.
• I have added tests that prove my fix is effective or that my feature works.
• I have provided a Changeset file (e.g. via pnpx changeset) to document my changes.

---

Note: This PR was developed with AI assistance (Claude). All code has been reviewed by the author.

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🦋 Changeset detected

Latest commit: 3ec8332

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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[jpoehnelt]

How does this compare to the request in #88?

[jpoehnelt]

Code duplication between reply.rs and forward.rs
Missing encode_path_segment() on the message-id in URL construction

[HeroSizy]

How does this compare to the request in #88?

This PR is a direct implementation of the feature request in #88. It adds +reply, +reply-all, and +forward as first-class helpers, covering most of the asks from that issue:

• Reply to a message by ID with automatic threading (In-Reply-To, References, threadId)
• Reply-all with proper recipient dedup
• Forward with the original message quoted
• --cc and --remove flags for adding/dropping recipients without reconstructing the list

One thing not yet covered: attachment forwarding. The current +forward quotes the original message body but doesn't carry over attachments. That could be a follow-up if this lands — happy to open a separate issue to track it.

[HeroSizy]

Code duplication between reply.rs and forward.rs Missing encode_path_segment() on the message-id in URL construction

@jpoehnelt

Thanks for the review! Both points are fixed now — forward.rs reuses OriginalMessage, fetch_message_metadata(), and send_raw_email() from reply.rs, and the message ID goes through encode_path_segment() in the URL construction.

Sorry about the initial state — I had an AI agent push before I'd properly reviewed. Everything's been cleaned up since.

A couple of questions:

1. forward.rs currently reaches into reply.rs via super::reply:: for shared types. Would you prefer those extracted into a common.rs within the gmail module?

2. We've been patching the hand-rolled mailbox parser for edge cases (escaped quotes, commas in display names, etc.) and it feels like a losing battle. Would you be open to bringing in an RFC 5322-compliant address parsing crate so we can drop the custom code entirely?

[jpoehnelt]

.

[jpoehnelt]

Nice work addressing the prior feedback — dedup and encode_path_segment() look good. A few things to address:

• Query params in URL string — fetch_message_metadata manually interpolates ?format=metadata&metadataHeaders=... into the URL. Per AGENTS.md, use reqwest .query() instead
• No From header — replies/forwards omit From:. Gmail infers it, but this breaks with aliases/send-as. Consider a --from flag or document the limitation
• Missing MIME headers — raw messages lack Content-Type: text/plain; charset=utf-8 and MIME-Version: 1.0, which can cause encoding issues with non-ASCII text
• Visibility — ReplyConfig and ForwardConfig are pub but only used within helpers::gmail; should be pub(super)
• Mailbox parser — agree with your suggestion to replace the hand-rolled split_mailbox_list with an RFC 5322 crate (mailparse etc.) in a follow-up
• CLA — cla: no label is present, needs signing before merge

[codecov]

Codecov Report

❌ Patch coverage is 77.83559% with 213 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.73%. Comparing base (f6d74b0) to head (3ec8332).
⚠️ Report is 36 commits behind head on main.

Files with missing lines	Patch %	Lines
src/helpers/gmail/reply.rs	79.42%	137 Missing ⚠️
src/helpers/gmail/mod.rs	64.00%	54 Missing ⚠️
src/helpers/gmail/forward.rs	84.82%	22 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #105      +/-   ##
==========================================
+ Coverage   55.19%   56.73%   +1.54%     
==========================================
  Files          38       40       +2     
  Lines       13166    14127     +961     
==========================================
+ Hits         7267     8015     +748     
- Misses       5899     6112     +213     

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