Add support for issue fields values to issues.read and issues.write

[kelsey-myers]

• depends on https://github.com/github/github/pull/433228

Summary

This PR is passing issue field values to the issue write & read tools, which now (after #2452) support this.

• should go in after https://github.com/github/github/pull/432297 because issues_write is using that endpoint

Why

• Fixes https://github.com/github/plan-track-agentic-toolkit/issues/37
• fixes https://github.com/github/plan-track-agentic-toolkit/issues/39

What changed

• the go-gothub lib was updated to pass issue field value sto rest api
• the repo upgraded to use v0.87 of go-github
• we're now using new params for IssueFieldValues

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added

Prompts tested (tool changes only)

• added tests to make sure that passing fields works, as well as retrieving them

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

• Linted locally with ./script/lint
• Tested locally with ./script/test

Docs

• Not needed
• Updated (README / docs / examples)

[kelsey-myers]

Tools tested on this branch

list_issue_fields

Inputs:

param	type	required	notes
owner	string	yes	repo owner or org login
repo	string	no	if omitted, returns org-level fields

Output: array of issue field definitions

[
  {
    "id": "IFSS_1",
    "full_database_id": 99,
    "name": "Priority",
    "data_type": "SINGLE_SELECT",
    "visibility": "ALL",
    "options": [
      { "id": "OPT_1", "name": "High", "color": "red" },
      { "id": "OPT_2", "name": "Low", "color": "blue" }
    ]
  },
  {
    "id": "IFT_2",
    "full_database_id": 42,
    "name": "DRI",
    "data_type": "TEXT",
    "visibility": "ORG_ONLY"
  }
]

---

issue_write (create / update)

New input: issue_fields — array of field values to set on the issue. Each item requires field_name and either value or field_option_name (not both).

{
  "issue_fields": [
    { "field_name": "Priority", "field_option_name": "High" },
    { "field_name": "DRI", "value": "monalisa" },
    { "field_name": "Due Date", "value": "2026-06-01" }
  ]
}

• Use field_option_name for SINGLE_SELECT fields — the server validates the option exists before calling the API
• Use value for TEXT, NUMBER, and DATE fields

Output: unchanged — { "id": "...", "url": "..." }

---

issue_read (method: get)

Inputs: unchanged

Output: the response now includes a field_values array alongside the standard issue fields:

{
  "number": 123,
  "title": "...",
  "field_values": [
    { "field_name": "Priority", "value": "High" },
    { "field_name": "DRI", "value": "monalisa" }
  ]
}

The raw issue_field_values from the REST response is replaced with this normalised GraphQL-sourced field_values for consistency with list_issues and search_issues.

[Copilot]

Pull request overview

This PR extends the issues tool surface to support reading and writing GitHub Issues 2.0 custom field values, aligning issue_read/issue_write behavior with the newer REST/GraphQL capabilities introduced alongside the go-github upgrade.

Changes:

• Added issue_fields input to issue_write, including name-based resolution of field IDs and (for single-select) option validation.
• Expanded issue_read output handling to include REST issue_field_values, and added best-effort GraphQL enrichment to normalize to field_values where possible.
• Updated minimal/DTO types and unit tests to cover issue field value parsing and write request shaping.

Show a summary per file

File	Description
README.md	Documents the new issue_fields input for issue_write.
pkg/github/minimal_types.go	Adds REST-backed minimal issue field value types and separates REST issue_field_values from GraphQL-normalized field_values.
pkg/github/issues.go	Implements parsing + GraphQL metadata resolution for issue_fields, wires field values into create/update, and adjusts search/get enrichment paths.
pkg/github/issues_test.go	Adds/updates tests for get/write behavior involving issue field values.
pkg/github/issue_fields.go	Fetches/stores GraphQL fullDatabaseId for issue fields and adds parsing helper.
pkg/github/issue_fields_test.go	Updates expectations to include fullDatabaseId/DatabaseID.
pkg/github/toolsnaps/issue_write.snap	Updates tool schema snapshot to include issue_fields.
docs/insiders-features.md	Reflects the issue_fields parameter in generated docs.
docs/feature-flags.md	Reflects the issue_fields parameter in generated docs.

Copilot's findings

Comments suppressed due to low confidence (1)

pkg/github/issues.go:1599

• searchIssuesHandler now always performs GraphQL field_values enrichment whenever there are results, and returns an error if GraphQL is unavailable or the query fails. This looks like a regression of the documented behavior of FeatureFlagIssueFields (which is meant to gate search_issues field_values enrichment); please restore the feature-flag check so search_issues works without GraphQL issue fields features enabled.

	var fieldValuesByID map[string][]MinimalFieldValue
	if len(result.Issues) > 0 {
		gqlClient, err := deps.GetGQLClient(ctx)
		if err != nil {
			return utils.NewToolResultErrorFromErr(errorPrefix+": failed to get GitHub GraphQL client", err), nil
		}
		fieldValuesByID, err = fetchIssueFieldValuesByNodeID(ctx, gqlClient, result.Issues)
		if err != nil {
			return ghErrors.NewGitHubGraphQLErrorResponse(ctx, errorPrefix+": failed to fetch issue field values", err), nil
		}
	}

• Files reviewed: 9/9 changed files
• Comments generated: 2